chapter2- Atoms and Nuclei
核能专业英语试卷库
核能专业英语试题（A卷）考试时间：90分钟姓名：班级：学号：The most elementary concept is that matter is composed of individual particles – atoms – that retain their identity as elements in ordinary physical and chemical interactions. Thus a collection of helium atoms that forms a gas has a total weight that is the sum of the weights of the individual atoms. Also, when two elements combine to form a compound, the total weight of the new substance is the sum of the origin elements.1.公认的物质的概念是：物质是由单个粒子——原子组成，在普通的化学和物理反应中原子保持了元素的特性。
因此，因此一团由氦原子组成的气体的重量就是其中每一个原子重量的总和。
同样，当两种元素结合成化合物时，新物质的总重量是原先的元素的质量之和。
Bohr assumed that the atom consists of a single electron moving at constant speed in a circular orbit about a nucleus --the proton--as sketched in Fig. X.X. Each particle has an electric charge of l.6×l0-l9 coulombs, but the proton has a mass that is 1836 times that of the electron.2.波尔假设（氢）原子由一个单独的电子绕着一个核子——质子，以圆形轨道作恒定速度的移动——见图X.X，每个粒子有l.6×l0-l9库伦的电量，质子的质量是电子质量的1836倍。
第2章原子结构和原子光谱[3]
![第2章原子结构和原子光谱[3]](https://img.taocdn.com/s3/m/cb0841641eb91a37f1115c57.png)
3S 1S
m
1 0
l
-1
m
1
l
m
1 1 1 0 0 0 0 0 0 0 0 0 -1 -1 -1
s
↑
↑
-1 0 0 -1 2
↑
1
↓
↓↑
0 1 0 1 0
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Atomic terms symbols for two equivalent electrons
12
Physical Chemistry I
Chapter II Atomic Structure and Spectrum
l - l coupling
Summary
s-s coupling
L-S coupling
Magnetic field
20112011-9-30 Chemistry Department of Fudan University 13
L - Scoupling: the orbital momenta for all electrons is coupled to obtain a total orbital angular momentum L and then the individual spin angular momenta is coupled to obtain the total spin angular momentum S. The total angular momentum J is then obtained by vector addition of L and S.
APES_Chapter_2_Science_Matter_Energy_and_Systems_2010-09
Science
world follow orderly cause-and-effect patterns that can be understood through careful observation, measurements, experimentation, and modeling.
Concept
2-1 Scientists collect data and develop theories, models, and laws about how nature works. – endeavor to discover how nature works and to use that knowledge to make predictions about what is likely to happen in nature.
• Studies how climate systems work, document past
climate changes, and project future changes.
The 4th IPCC report, 2007 • Very likely (90-99% probability) that the
story
• Polynesians arrived about 800 years ago
• Population may have reached 3000
• Used trees in an unsustainable manner, but rats
may have multiplied and eaten the seeds of the trees
应用地球化学元素丰度数据手册-原版
应用地球化学元素丰度数据手册迟清华鄢明才编著地质出版社·北京·1内容提要本书汇编了国内外不同研究者提出的火成岩、沉积岩、变质岩、土壤、水系沉积物、泛滥平原沉积物、浅海沉积物和大陆地壳的化学组成与元素丰度，同时列出了勘查地球化学和环境地球化学研究中常用的中国主要地球化学标准物质的标准值，所提供内容均为地球化学工作者所必须了解的各种重要地质介质的地球化学基础数据。
本书供从事地球化学、岩石学、勘查地球化学、生态环境与农业地球化学、地质样品分析测试、矿产勘查、基础地质等领域的研究者阅读，也可供地球科学其它领域的研究者使用。
图书在版编目（CIP）数据应用地球化学元素丰度数据手册/迟清华，鄢明才编著. －北京：地质出版社，2007.12ISBN 978－7－116－05536－0Ⅰ. 应… Ⅱ. ①迟…②鄢…Ⅲ. 地球化学丰度－化学元素－数据－手册Ⅳ. P595－62中国版本图书馆CIP数据核字（2007）第185917号责任编辑：王永奉陈军中责任校对：李玫出版发行：地质出版社社址邮编：北京市海淀区学院路31号，100083电话：（010）82324508（邮购部）网址：电子邮箱：zbs@传真：（010）82310759印刷：北京地大彩印厂开本：889mm×1194mm 1/16印张：10.25字数：260千字印数：1－3000册版次：2007年12月北京第1版•第1次印刷定价：28.00元书号：ISBN 978－7－116－05536－0（如对本书有建议或意见，敬请致电本社；如本社有印装问题，本社负责调换）2关于应用地球化学元素丰度数据手册（代序）地球化学元素丰度数据，即地壳五个圈内多种元素在各种介质、各种尺度内含量的统计数据。
它是应用地球化学研究解决资源与环境问题上重要的资料。
将这些数据资料汇编在一起将使研究人员节省不少查找文献的劳动与时间。
这本小册子就是按照这样的想法编汇的。
化学A-level备考教学计划(schedule format)
西乡中学国际部2013—2014学年度第二学期A-LEVEL备考教学计划（TeachingSchedule）课程负责人（Course Leader）：Joyce 授课教师（Teachers）：Gina授课班级(Class）：课程名称（Course）：Chemistry A Level采用教材及资料（Teaching Material）：Cambridge Chemistry AS Level and A Level学期总课时(Periods of Lessons)：54 节；其中：理论授课(Theory) 36 节；实践教学含词汇检测Practice（次）节；练习课Exercise 15 节；测验考试含周测模考、月考、期中期末考Test（ 3 次）节；机动安排(Flexible Arrangement) 3 节；备注：1、以周为单位填写授课授课形式、授课内容、实践教学内容、作业配备等。
2、授课形式包括：理论教学、实践教学、课堂练习等。
3、实践教学包括：实验、实习等。
教研组长Team Leader（签名）：教学主管Teaching Director（签章）：西乡中学国际部2014 年04月06 日周次(Week)周学时(Hours)讲课内容、课时 (Content&Page)（写明章节、题目名称及页码）授课重难点及目标(Focus&Objective）讨论、习题、见习、实习、测试、考试（Exercise&Test）备注（Remarks）第 8 周 4自习天气原因测试Chapter1 Atomic structure（1）1.recognise and describle protons, neutrons andelectrons in terms of their relative charges andrelative masses;2.describle the contribution of protons andneutrons to atomic nuclei in terms of atomicnumber and mass number;3.deduce the number of protons, neutrons andelectrons present in both atoms and ions fromgiven atomic and mass number;4.describe the behavior of protons, neutrons andelectrons in electric field.Chapter1 Atomic structure（2）1.explain the terms first ioniation energy andsuccessive ionisation energies of an element interms of 1mol of gaseous atoms or ions;2.explain that ionisation energies are influencedby nuclear charge, atomic radius and electronshielding;3.predict the number of electrons in eachprincipal quantum shell of an element from itssuccessive ionisation energies;4. describe the shapes of s and p orbitals第 9 周 3 Chapter1 Atomic structure（3）1.describe the numbers and relative energies ofthe s, p and d orbitals for the principal quantumnumbers 1,2,3 and also the 4s and 4p orbitals.2.deduce the electronic configurations of atomsup to Z=36 and ions, given the atomic numberand charge, limited to s and p blocks up to Z=36习题课The key point of chapter 1Chapter2 Atoms, molecules andstoichiometry（1）1.define the terms relative atomic mass, relativeisotopic mass, ect, based on the 12C scale2.describe the basic principles f the massspectrometer3.intepret mass spectra in terms of isotopicabundnces4.calcuate the relative atomic mass of an elementgiven the relative abundances of its isotopes, orits mass spectrum5.define the mole in terms of Avgadro’s constantand molar mass as the mass of 1 mole of a substance第 10 周 3 Chapter2 Atoms, molecules andstoichiometry（2）1define the terms empirical formula andmolecular formula2.calcuate empirical formula and molecularformula, using composition by mass3.construct balanced chemical equations4.perform calculations involving reacting masses,volumes of gases and volumes andconcentrations of solutions in simple acid-basetitrations, and use those calculations to deducesstoichiometric relationships期中考试习题课The key point of chapter 2Chapter3 Chemical bonding andstructure（1）1.describe ionic bonding as the electrostaticattraction between two oppositely charged ions,including the use of dot-and-cross diagrams2.describe, in simple terms, the lattice structureof sodium chloride3.describe a covalent bond as a pair of electronsshared between two atoms4.describe, including the use of dot-and-crossdiagrams, covalent bonding and dative covalent(coordinate) bonding5.appreciate that, between the extremes of ionicand covalent bonding, there is a gradualtransition from one extreme to the other6.describe electronegativity as the ability of anatom to attract the bonding electrons in acovalent bond第 11 周 4Chapter3 Chemical bondingand structure（2）1.explain and predict the shapes of, and bondangles in, molecules and ions by using thequalitative model of 2.electron-pair repulsion upto 4 electrons pairs3.describe metallic bonding, present in a giantmetallic lattice structure, as the attraction of alattice of positive ions to sea of mobile electrons4.describe intermolecular force, based oninstantaneous and permanent dipoles5.describe, in simple terms, the giant molecularstructures of graphite and diamondChapter3 Chemical bonding andstructure（3）1.describe hydrogen bonding between moleculescontaining –OH and -NH groups, typified bywater and ammonia2.describe and explain the anomalous propertiesof water resulting from hydrogen bonding3.describe, interpret or predict physicalproperties in terms of the types, motion andarrangement of particles between them, anddifferent types of bonding4.deduce the type of bonding present in asubstance, given suitable information习题课The key point of chapter 3Chapter4 States of matter（1）1.describe, using a kinetic-molecular model, the solid, liquid and gaseous states, melting, vaporization and vapour pressure2.state the basic assumptions of the kinetic theory as applied to an ideal gas3.explain qualitatively, in terms of intermolecular forces and molecular size第 12 周 3 Chapter4 States of matter（2）1.state and use the ideal gas equation PV=nRT incalculations, including the determination of therelative molecular mass of a volatile liquid2.describe in simple terms lattice structures ofcrystalline solids which are ionic, simplemolecular, giant molecular, hydrogen-bonded ormetallic3.outline the importance of hydrogen bonding tothe physical properties of substancesChapter4 States of matter（3）1.describe and interpret the uses of aluminium,copper and their alloys in terms of their physicalproperties2.understand that materials are a finite resourceand that recycling processes are important3.suggest from quoted physical data the type ofstructure and bonding present in a substance 习题课The key point of chapter 4第 13 周 4 Chapter5 Chemical energies（1）1.explain that some chemical reactions areaccompanied by enthalpy changes, principally inthe form of heat energy. The enthalpy changescan be exothermic or endothermic2.recognize the importance of oxidation as anexothermic process3.recognize that endothermic processes requirean input of heat energyChapter5 Chemical energies（2）1.construct a simple enthalpy profile diagram fora reaction to show the difference in enthalpy ofthe reactants compared with that of the products2.explain chemical reactions in terms of enthalpychanges associated with the breaking and makingof chemical bonds3.explain and use the terms enthalpy change ofreaction, standard conditions and bond enthalpyChapter5 Chemical energies（3）1.calculate enthalpy changes from appropriate experimental results, including the use of the relationshipe Hess’s law to construct enthalpy cycles and carry out calculations using such cycles and relevant enthalpy terms习题课The key point of chapter 5第 14 周 4 Chapter6 Electrochemistry1.describe and explain redox processes in termsof electron transfer an of changes in oxidationstate2.explain, including the electrode reactions, theindustrial processes of the electrolysis of brine,using a diaphragm cell,ectChapter7 Equilibria（1）1.explain the features of a dynamic equilibrium2.state Le Chatelier’s principle and apply it todeduce qualitatively the effect of a change intemperature, concentration or pressure on ahomogeneous system in equilibriumChapter7 Equilibria（2）1.deduce, for homogeneous reactions,expressions for the equilibrium constants K C, interms of concentrations, and K P, in terms ofpartial pressures2.calculate the values of the equilibriumconstants K C or K P including determination ofunits, given appropriate data3.calculate a concentration or partial pressurepresent at equilibrium, given appropriate data Chapter7 Equilibria（3）1.describe and explain the conditions used in theHaber process and the Contact process asexamples of the importance of a compromisebetween chemical equilibrium and reaction ratein the chemical industry2.describe and use the Bronsted-Lowry theory ofacids and bases, to include conjugate acid-basepairs3.explain qualitatively, in terms of dissociation,the differences between strong and weak acidsand between strong and weak bases in terms ofthe extent of dissociation习题课The key point of chapter 71.describe qualitatively, in terms of collisiontheory, the effect of concentration changes on therate of a reaction2.explain why an increase in the pressure of agas, increasing its concentration, may increase第 15 周 4 Chapter8 Reaction kinetics（1）the rate of a reaction involving gases3.explain qualitatively, using the Boltzmanndistribution and enthalpy profile diagrams, whatis meant by the term activation energy4.describe qualitatively, using the Boltzmanndistribution and enthalpy profile diagrams, theeffect of temperature changes on the rate of areactionChapter8 Reaction kinetics（2）1.explain what is meant by a catalyst2.explain that, in the presence of a catalyst, areaction proceeds via a different route3.interpret catalytic behavior in terms of theBoltzmann distribution and enthalpy profilediagrams4.describe enzymes as biological catalysts whichmay have specific activity习题课The key point of chapter 8第 16 周 4 Chapter9 Chemical periodicity（1）1.describe the Periodic Table I terms of thearrangement of elements by increasing atomicnumber, in Periods showing repeating physicaland chemical properties2.classify the elements into s, p and d blocks3.describe qualitatively the variations in atomicradius, ionic radius, melting point in electricalconductivity of the elements4.explain qualitatively the variation in atomicradius and ionic radius5.interpret the variation in melting point and inelectrical conductivity in terms of the presence ofsimple molecular, giant molecular or metallicbonding in the elementsChapter9 Chemical periodicity（2）1.explain the variation in the first ionizationenergy2.describe the reactions, if any, of the elementswith oxygen, with chlorine and with water3.state and explain the variation in oxidationnumber of the oxides and chlorides4.describe the reactions of the oxides with water5.describe and explain the acid-base behavior ofoxides and hydroxides6.describe and explain the reactions of thechlorides with water1.suggest the types of chemical bonding presentin chlorides and oxides from observations oftheir chemical and physical properties2.predict the characteristic properties of anChapter9 Chemical periodicity（3）element in a given Group by using knowledge ofchemical periodicity3.deduce the nature, possible position in thePeriodic Table, and identity of unknown elementsfrom given information of physical and chemicalproperties习题课The key point of chapter 9第 17 周 2 Chapter10 Group II（1）1.describe and explain the trends in electronicconfigurations, atomic radii and ionizationenergies of the Group II elements2.interpret and make predictions from thechemical and physical properties of the Group IIelements and their compounds3.show awareness of the importance and use ofGroup II elements and their compounds, withappropriate chemical explanations4.describe oxidation and reduction in terms ofelectron transfer and changes in oxidation state端午+高考Chapter10 Group II（2）1. describe the redox reactions of the elementsMg to Ba with oxygen and water and explain thetrend in reactivity in terms of ionization energies2.describe the reactions of Mg, MgO and MgCO3with hydrochloric acid3.describe the behavior of Group II oxides withwater4.describe the thermal decomposition of thenitrates and carbonate of Group II elements第18周 4Chapter10 Group II（3）1.describe the thermal decomposition of CaCO3to form CaO and the subsequent formation ofCa(OH)2 with water2.describe lime water as an aqueous solution ofCa(OH)2 and state its approximate pH3.describe the reaction of lime water with carbondioxide forming CaCO3, and with excess carbondioxide, forming Ca(HCO3)2, as in hard water 习题课The key point of chapter 10Chapter12 Group VII（1）1.explain trend in the volatilities of chlorine,bromine and iodine in terms of van der Waals’forces2.describe the relative reactivity of the elementsCl2, Br2and I2in displacement reactions and3.explain this trend in terms of oxidizing powderdescribe and explain the reactions of theelements with hydrogen4.describe and explain the relative thermalstabilities of the hydrides and interpret these interms of bond enthalpiesChapter12 Group VII（2）1.describe the characteristic reactions of the Cl-, Br- and I-with aqueous silver ions followed by aqueous ammonia2.describe and explain the reactions of halide ions with concentrated sulphuric acid3.describe and interpret, in terms of changes in oxidation state, the reactions of chlorine with cold, dilute aqueous sodium hydroxide to form bleach and with hot aqueous sodium hydroxide4.explain the use of chlorine in water purification recognize the industrial importance and environmental significance of the halogens and their compounds第 19 周 4习题课The key point of chapter 12Chapter14 Nitrogen and sulphur（1）1.explain the lack of reactivity o f nitrogen2.describe the displacement of ammonia from itssalts3.outline the industrial importance of ammoniaand of nitrogen compounds derived fromammonia4.explain the environmental consequences of theuncontrolled5.explain why atmosphere oxides of nitrogen repollutants, including their use in the oxidation ofatmospheric sulphur dioxideChapter14 Nitrogen and sulphur（2）1.describe the formation of atmospheric sulphurdioxide from the combustion of sulphurcontaminated carbonaceous fuels2.describe the role of sulphur dioxide in theformation of acid rain and the environmentalconsequences of acid rain3.describe the main detail of the Contact processand outline the industrial importance of sulphuricacid4.describe the use of sulphur dioxide in foodpreservation习题课The key point of chapter 14Chapter15 Introduction to organicchemistry（1）1.interpret and use the terms nomenclature,molecular formula, general formula, structuralformula, displaced formula, skeletal formula,homologous series and functional groupe IUPAC rules for naming organiccompounds1.perform calculation, involving use of the moleconcept and reacting quantities, to determine the第 20 周 4 Chapter15 Introduction to organicchemistry（2）percentage yield of a reaction2.describe and explain structural isomerism incompounds with the same molecular formula butdifferent structural formulaeChapter15 Introduction to organicchemistry（3）1.interpret and use the term stereoisomerism interms of cis-trans and optical isomerism2.describe and explain cis-trans isomerism inalkenes, in terms of restricted rotation about adouble bond3.determine the possible structural and cis-transisomers of an organic molecule of givenmolecular formulaChapter15 Introduction to organicchemistry（4）1.explain the term chiral centre and identify anychiral centres in a molecule of given structuralformula2.understand that chiral molecules preparedsynthetically in the laboratory may contain amixture of optical isomers, whereas molecules ofthe same compound produced naturally in livingsystems will often be present as one opticalisomer only第 21 周 4习题课The key point of chapter 15根据实际情况安排实验课机动安排第22周 3 复习课Chapter 1—chapter 5期末考试复习课Chapter 6—chapter 9复习课Chapter 10—chapter 15。
Chapter 2 Atoms, Molecules, and Ions
Chapter 2 Atoms, Molecules, and Ions2.1 Atoms and Ions in Combination1. Molecular and Ionic CompoundsWhen two or more atoms combine chemically they form a molecule.(A molecule is the smallest particle of a pure substance that has the composition and properties of that substance and is capable of independent existence. ) The naturally occurring forms of some elements are diatomic molecules (molecules consisting of two atoms) or polyatomic molecules (which contain more than two atoms). We refer to the compounds composed of molecules as molecular compounds. When an atom gains one or more electrons it acquires a negative charge and is known as an anion; when an atom loses one or more electrons it acquires a positive charge and is known as a cation. An ionic compound (e. g. NaC1) consists of positive and negative ions (Na+ and C1-) held together by electrical attraction. The chemical formula of an ionic compound gives the ratio of ions, but individual molecules are not ordinarily present.Chemical Formulas for Molecules of ElementsMonatomic Molecules Diatomic Molecules Polyatomic MoleculesHe Helium H2Hydrogen P4 Phosphorus Neon O2Oxygen As4ArsenicNeAr Argon N2Nitrogen Sb4 AntimonyKr Krypton F2Fluorine S8SulfurXe Xenon C12Chlorine Se8SeleniumRn Radon I2 IodineSome Monatomic IonsH+,Li+,Na+,K+,Cu+,Cu2+,Ag+,Mg2+,Ca2+,Zn2+,Hg2+,Fe2+,Fe3+,A13+, Bi3+, Cr2+Cr3+,Co2+,Co3+,Mn2+,Mn3+,Sn2+,Pb2+,F-,C1-,Br-,I-,O2-,S2-,N3-,P3-2. Formulas for Chemical CompoundsA chemical formula gives the symbols for the elements in a compound with subscripts indicating the number of atoms of each element present. For a molecular compound, the formula represents the number of atoms in one molecule. For an ionic compound, the formula gives the ratio of ions present in the simplest unit, or one formula unit. A structural formula is essentially a diagram showing how the atoms in a compound or ion are linked to each other by chemical bonds. The formula Mg2+ (NO3-)2 is read "M-G-N-oh-three-taken-twice."Chemical formulas for Some Simple CompoundsWater H2OCarbon monoxide COCarbon dioxide CO2Sulfur dioxide SO2Silver sulfide Ag2SPotassium chloride KC1Ammonia NH3Methane CH4Polyatomic IonsNH4+Ammonium ion NO2-Nitrite ionCN- Cyanide ion NO3-Nitrate ionCO32-Carbonate ion O22-Peroxide ionClO3-Chlorate ion OH-Hydroxide ionC1O4-Perchlorate ion PO3-Phosphate ionCrO42-Chromate ion SO32-Sulfite ionCr2O2-Dichromate ion SO42-Sulfate ionMnO4-Permanganate ion CH3COO-Acetate ionStructure formulas: SOO 2-and OHH H H H and3. Naming Chemical CompoundsThe rules that govern the naming of chemical compounds are knowncollectively as chemical nomenclature. In the Stock system, the name of acation consists of the name of the element, the charge on the ion as aRoman numeral in parentheses (parenthesis), and the word "ion". Thename of a monatomic anion (e.g., Cl -) consists of the name of the elementwith the ending "ide", followed by the word "ion". A binary compound isone containing atoms or ions of only two elements. Salts are ioniccompounds formed between cations and the anions of acids. For binarymolecular compounds, prefixes are used to indicate the number of atomsof each element present. Older System Stock SystemMn 2+ Manganous ion Manganese ( II ) ionMn 3+ Manganic ion Manganese ( I ) ionCu + Cuprous ion Copper ( I ) ionCu 2+ Cupric ion Copper ( II ) ionCl - Chloride ionO 2- Oxide ionN 3- Nitride ionN 3- Azide ionO 22- Peroxide ionCuC1 Cuprous chloride Copper ( I ) chlorideCuCl 2 Cupric chloride Copper ( II ) chlorideNa 3P Sodium phosphideA12(SO 4)3 Aluminum sulfateAcid AnionHydrochloric acid HCl(aq) Chloride ion C1-Carbonic acid H2CO3 (aq) Carbonate ion CO32-Hydrogen carbonate ion HCO3-Nitric acid HNO3Nitrate ion NO3-Nitrous acid HNO2 (aq) Nitrite ion NO2-Perchloric acid HClO4Perchlorate ion C1O4-Phosphoric acid H3PO4Phosphate ion PO43-Hydrogen phosphate ion HPO42-Dihydrogen phosphate ion H2PO4-Hydrogen phosphite ion HPO32-Sulfuric acid H2SO4Sulfate ion SO42-Hydrogen sulfate ion HSO4-Sulfurous acid H2SO3 (aq) Sulfite ion SO32-Hydrogen sulfite ion HSO3-No. Indicated 1 2 3 4 5 6 7 8 9 10Prefix mono di tri tetra penta hexa hepta octa nona decaN2O dinitrogen monoxide IC1 iodine monochlorideN2O5 dinitrogen pentoxide SO3 sulfur trioxide4. Chemical EquationsThe substances that undergo changes in a chemical reaction are called the reactants, and the new substances formed are the products. The chemical change that takes place is represented with symbols and formulas in a chemical equation. All chemical equations must be balanced--the correct coefficients must be used for each species so that all the atoms of each element in the reactants can be accounted for in the products. Information about the states of reactants and products may be provided by symbols after the formulas. (g) for gas, (l) for liquid, (s) for solid, and (aq) for substances in aqueous solution. The transformation ofa neutral ionic compound into positive and negative ions, usually by dissolution in water, is called dissociation. The formation of ions from a molecular compound is known as ionization. For example,(1) P 4 + 6Cl 2 4PCl 3(read "One P 4 molecule plus six Cl 2 molecules yields four molecules of PCl 3. ")(2) N 2(g) + 3H 2(g) 2NH 3(g)(read "Gaseous nitrogen reacts with gaseous hydrogen at 400ºC and 250 atm pressure in thepresence of FeO （iron(II) oxide ）as a catalyst to produce gaseous ammonia. ")(3) NaCl(s) Na +(aq) + Cl -(aq)("solid sodium chloride dissociates into sodium ion in aqueous solution plus chloride ion in aqueous solution'')(4) HCl(g) H +(aq) + Cl -(aq)("hydrogen chloride : hydrochloric acid")2.2 Atomic, Molecular ,and Molar Mass Relationships1. Molecular MassThe molecular mass of a chemical compound is the sum of theatomic masses, in atomic mass units, of all the atoms in the formula of the compound. For example,number of atoms atomic mass (u/atom) mass (u)N 2 × 14.01 = 28.02O 5 × 16.00 = 80.00molecular mass of N 2O 5 = 108.02 u2. Avogadro's Number, The Mole, and Molar MassAvogadro's number is the number of atoms in exactly 12 g ofcarbon-12; it is equal to 6. 022×1023. A mole is a number of anything equal to Avogadro's number. The mole is the unit that provides the 400℃,250atm,FeO H 2O H 2Oconnection between masses on the microscopic level (measured in atomic mass units) and masses on the macroscopic level (measured in grams). The molar mass of a substance is the mass in grams of one mole of that substance.e.g.1 How many ozone molecules and how many oxygen atoms are present in 48.00g of ozone, O3?(48.00g)(1mole/48.00g)(6.022×1023 molecules/1mole)= 6.022 × 1023 molecules(6.022×1023molecules) (3 O atoms /1 molecule)= 1.807 × 1024 O atoms3. Molarity (M): Molar mass in SolutionsThe concentration of a substance in solution is a quantitative statement of the amount of solute in a given amount of solvent or solution. Concentrations are often given in moles per liter of solution, or molarity (M).e.g.1 An experiment called for the addition of 1.50 mol of NaOH in the form of a dilute solution. The only sodium hydroxide solution that could be found in the laboratory was a 2 L container marked "0.1035M NaOH". What volume of this solution would be required for the 1.50 mol of NaOH? If the 2 L container was full, would this be enough?(1.50 mol NaOH)(1L / 0.1035 mol NaOH) = 14.5 LNot enough2.3Composition of a Chemical Compound, Simplest andEmpirical Formulas, and Molecular Formulas The percentage (by mass) of each element present in a chemical compound is its percentage composition. The simplest formula of a compound gives the simplest whole-number ratio of the atoms it contains. An experimentally determined simplest formula is called an empirical formula; it can be determined from the percentage composition and the molar masses of the elements present. The molecular formula of a compound represents the actual number of atoms of each element present in a molecule. To find the molecular formula of a compound it is necessary to know both its empirical formula and its molecular or molar mass, which is usually some multiple of the mass calculated from the empirical formula.e.g. 1 A 3.91 g sample of potassium metal when burned in oxygen formed a compound weighing 7.11 g and containing only potassium and oxygen. What is the percentage composition of this compound?ω(K) = (3.91 g K / 7.11 g compound) (100%) = 55.0%ω(O) = (1 - 0.55) (100%) = 45.0%e.g. 2 The mineral cryolite contains 33% by mass of Na, 13% by mass of Al, and 54% by mass of F（fluorine）. Determine the empirical formula of the compound.Choose exactly 100 g of cryolite as a basis to solve the problem.Na A1 F No. of molesmol mol g g 4.1/99.2233= mol mol g g 48.0/98.2613= mol mol g g 8.2/00.1954= Mole ratio(n/n A1)9.248.04.1= 148.048.0= 8.548.08.2= Relative no. of atoms3 1 6e.g. 3 The empirical formula for a substance was determined to beCH. The approximate molar mass of the substance was experimentallyfound to be 79 g. What is the molecular formula of this molecularcompound? What is the exact molar mass?[79g / mole (CH)x ] / [(12.01+1.01)g / mol CH] = 6.1The molecular formula is (CH)6 = C 6H 6 and the exact molar mass is(13.02 g / mole) (6) = 78.12 g / mol。
化学专业英语电子版
Chapter 1 Matter and MeasurementChemistry is the science of matter and the changes it undergoes. Chemists study the composition, structure, and properties of matter. They observe the changes that matter undergoes and measure the energy that is produced or consumed during these changes. Chemistry provides an understanding of many natural events and has led to the synthesis of new forms of matter that have greatly affected the way we live.Disciplines within chemistry are traditionally grouped by the type of matter being studied or the kind of study. These include inorganic chemistry, organic chemistry, physical chemistry, analytical chemistry, polymer chemistry, biochemistry, and many more specialized disciplines, e.g. radiochemistry, theoretical chemistry.Chemistry is often called "the central science" because it connects the other natural sciences such as astronomy, physics, material science, biology and geology.1.1. Classification of MatterMatter is usually defined as anything that has mass and occupies space. Mass is the amount of matter in an object. The mass of an object does not change. The volume of an object is how much space the object takes up.All the different forms of matter in our world fall into two principal categories: (1) pure substances and (2) mixtures. A pure substance can also be defined as a form of matter that has both definite composition and distinct properties. Pure substances are subdivided into two groups: elements and compounds. An element is the simplest kind of material with unique physical and chemical properties; it can not be broken down into anything simpler by either physical or chemical means. A compound is a pure substance that consists of two or more elements linked together in characteristic and definite proportions; it can be decomposed by a chemical change into simpler substances with a fixedmass ratio. Mixtures contain two or more chemical substances in variable proportions in which the pure substances retain their chemical identities. In principle, they can be separated into the component substances by physical means, involving physical changes. A sample is homogeneous if it always has the same composition, no matter what part of the sample is examined. Pure elements and pure chemical compounds are homogeneous. Mixtures can be homogeneous, too; in a homogeneous mixture the constituents are distributed uniformly and the composition and appearance of the mixture are uniform throughout. A solutions is a special type of homogeneous mixture. A heterogeneous mixture has physically distinct parts with different properties. The classification of matter is summarized in the diagram below:Matter can also be categorized into four distinct phases: solid, liquid, gas, and plasma. The solid phase of matter has the atoms packed closely together. An object that is solid has a definite shape and volume that cannot be changed easily. The liquid phase of matter has the atoms packed closely together, but they flow freely around each other. Matter that is liquid has a definite volume but changes shape quite easily. Solids and liquids are termed condensed phases because of their well-defined volumes. The gas phase of matter has the atoms loosely arranged so they can travel in and out easily. A gas has neither specific shape nor constant volume. The plasma phase of matter has the atoms existing in an excited state.1.2. Properties of MatterAll substances have properties, the characteristics that give each substance its unique identity. We learn about matter by observing its properties. To identify a substance, chemists observe two distinct types of properties, physical and chemical, which are closely related to two types of change that matter undergoes.Physical properties are those that a substance shows by itself, without changing into or interacting with another substance. Some physical properties are color, smell, temperature, boiling point, electrical conductivity, and density. A physical change is a change that does not alter the chemical identity of the matter. A physical change results in different physical properties. For example, when ice melts, several physical properties have changed, such as hardness, density, and ability to flow. But the sample has not changed its composition: it is still water.Chemical properties are those that do change the chemical nature of matter. A chemical change, also called a chemical reaction, is a change that does alter the chemical identity of the substance. It occurs when a substance (or substances) is converted into a different substance (or substances). For example, when hydrogen burns in air, it undergoes a chemical change because it combines with oxygen to form water.Separation of MixturesThe separation of mixtures into its constituents in a pure state is an important process in chemistry. The constituents of any mixture can be separated on the basis of their differences in their physical and chemical properties, e.g., particle size, solubility, effect of heat, acidity or basicity etc.Some of the methods for separation of mixtures are:(1)Sedimentation or decantation. To separatethe mixture of coarse particles of a solidfrom a liquid e.g., muddy river water.(2)Filtration. To separate the insoluble solidcomponent of a mixture from the liquidcompletely i.e. separating the precipitate(solid phase) from any solution.(3)Evaporation. To separate a non-volatilesoluble salt from a liquid or recover thesoluble solid solute from the solution.(4)Crystallization. To separate a solidcompound in pure and geometrical form.(5)Sublimation. To separate volatile solids,from a non-volatile solid.(6)Distillation. To separate the constituents of aliquid mixture, which differ in their boilingpoints.(7)Solvent extraction method. Organiccompounds, which are easily soluble inorganic solvents but insoluble or immisciblewith water forming two separate layers canbe easily separated.1.3 Atoms, Molecules and CompoundsThe fundamental unit of a chemical substance is called an atom. The word is derived from the Greek atomos, meaning “undivisible”or “uncuttable”.An atom is the smallest possible particle of a substance.Molecule is the smallest particle of a substance that retains the chemical and physical properties of the substance and is composed of two or more atoms;a group of like or different atoms held together by chemical forces. A molecule may consist of atoms of a single chemical element, as with oxygen (O2), or of different elements, as with water (H2O).A chemical element is a pure chemical substance consisting of one type of atom distinguished by its atomic number, which is the number of protons in its nucleus. The term is also used to refer to a pure chemical substance composed of atoms with the same number of protons. Until March 2010, 118 elements have been observed. 94 elements occur naturally on earth, either as the pure element or more commonly as a component in compounds. 80 elements have stable isotopes, namely all elements with atomic numbers 1 to 82, except elements 43 and 61 (technetium and promethium). Elements with atomic numbers 83 or higher (bismuth and above) are inherently unstable, and undergo radioactive decay. The elements from atomic number 83 to 94 have no stable nuclei, but are nevertheless found in nature, either surviving as remnants of the primordial stellar nucleosynthesisthat produced the elements in the solar system, or else produced as short-lived daughter-isotopes through the natural decay of uranium and thorium. The remaining 24 elements so are artificial, or synthetic, elements, which are products of man-induced processes. These synthetic elements are all characteristically unstable. Although they have not been found in nature, it is conceivable that in the early history of the earth, these and possibly other unknown elements may have been present. Their unstable nature could have resulted in their disappearance from the natural components of the earth, however.The naturally occurring elements were not all discovered at the same time. Some, such as gold, silver, iron, lead, and copper, have been known since the days of earliest civilizations. Others, such as helium, radium, aluminium, and bromine, were discovered in the nineteenth century. The most abundant elements found in the earth’s crust, in order of decreasing percentage, are oxygen, silicon, aluminium, and iron. Others present in amounts of 1% or more are calcium, sodium, potassium, and magnesium. Together, these represent about 98.5% of the earth’s crust.The nomenclature and their origins of all known elements will be described in Chapter 2.A chemical compound is a pure chemical substance consisting of two or more different chemical elements that can be separated into simpler substances by chemical reactions. Chemical compounds have a unique and defined chemical structure; they consist of a fixed ratio of atoms that are held together in a defined spatial arrangement by chemical bonds. Compounds that exist as molecules are called molecular compounds. An ionic compound is a chemical compound in which ions are held together in a lattice structure by ionic bonds. Usually, the positively charged portion consists of metal cations and the negatively charged portion is an anion or polyatomic ion.The relative amounts of the elements in a particular compound do not change: Every molecule of a particular chemical substance contains acharacteristic number of atoms of its constituent elements. For example, every water molecule contains two hydrogen atoms and one oxygen atom. To describe this atomic composition, chemists write the chemical formula for water as H2O.The chemical formula for water shows how formulas are constructed. The formula lists the symbols of all elements found in the compound, in this case H (hydrogen) and O (oxygen). A subscript number after an element's symbol denotes how many atoms of that element are present in the molecule. The subscript 2 in the formula for water indicates that each molecule contains two hydrogen atoms. No subscript is used when only one atom is present, as is the case for the oxygen atom in a water molecule. Atoms are indivisible, so molecules always contain whole numbers of atoms. Consequently, the subscripts in chemical formulas of molecular substances are always integers. We explore chemical formulas in greater detail in Chapter 2.The simple formula that gives the simplest whole number ratio between the atoms of the various elements present in the compound is called its empirical formula. The simplest formula that gives the actual number of atoms of the various elements present in a molecule of any compound is called its molecular formula. Elemental analysis is an experiment that determines the amount (typically a weight percent) of an element in a compound. The elemental analysis permits determination of the empirical formula, and the molecular weight and elemental analysis permit determination of the molecular formula.1.4. Numbers in Physical Quantities1.4.1. Measurement1.Physical QuantitiesPhysical properties such as height, volume, and temperature that can be measured are called physical quantity. A number and a unit of defined size are required to describe physical quantity, for example, 10 meters, 9 kilograms.2.Exact NumbersExact Numbers are numbers known withcertainty. They have unlimited number of significant figures. They arise by directly counting numbers, for example, the number of sides on a square, or by definition:1 m = 100 cm, 1 kg = 1000 g1 L = 1000 mL, 1 minute = 60seconds3.Uncertainty in MeasurementNumbers that result from measurements are never exact. Every experimental measurement, no matter how precise, has a degree of uncertainty to it because there is a limit to the number of digits that can be determined. There is always some degree of uncertainty due to experimental errors: limitations of the measuring instrument, variations in how each individual makes measurements, or other conditions of the experiment.Precision and AccuracyIn the fields of engineering, industry and statistics, the accuracy of a measurement system is the degree of closeness of measurements results to its actual (true) value. The precision of a measurement system, also called reproducibility or repeatability, is the degree to which repeated measurements under unchanged conditions show the same results. Although the two words can be synonymous in colloquial use, they are deliberately contrasted in the context of the scientific method.A measurement system can be accurate but not precise, precise but not accurate, neither, or both. A measurement system is called valid if it is both accurate and precise. Related terms are bias (non-random or directed effects caused by a factor or factors unrelated by the independent variable) and error(random variability), respectively. Random errors result from uncontrolled variables in an experiment and affect precision; systematic errors can be assigned to definite causes and affect accuracy. For example, if an experiment contains a systematic error, then increasing the sample size generally increases precision but does not improve accuracy. Eliminating the systematic error improves accuracy but does not change precision.1.4.2 Significant FiguresThe number of digits reported in a measurement reflects the accuracy of the measurement and the precision of the measuring device. Significant figures in a number include all of the digits that are known with certainty, plus the first digit to the right that has an uncertain value. For example, the uncertainty in the mass of a powder sample, i.e., 3.1267g as read from an “analytical balance” is 0.0001g.In any calculation, the results are reported to the fewest significant figures (for multiplication and division) or fewest decimal places (addition and subtraction).1.Rules for deciding the number of significantfigures in a measured quantity:The number of significant figures is found by counting from left to right, beginning with the first nonzero digit and ending with the digit that has the uncertain value, e.g.,459 (3) 0.206 (3) 2.17(3) 0.00693 (3) 25.6 (3) 7390 (3) 7390. (4)(1)All nonzero digits are significant, e.g., 1.234g has 4 significant figures, 1.2 g has 2significant figures.(2)Zeroes between nonzero digits aresignificant: e.g., 1002 kg has 4 significantfigures, 3.07 mL has 3 significant figures.(3)Leading zeros to the left of the first nonzerodigits are not significant; such zeroes merelyindicate the position of the decimal point:e.g., 0.001 m has only 1 significant figure,0.012 g has 2 significant figures.(4)Trailing zeroes that are also to the right of adecimal point in a number are significant:e.g., 0.0230 mL has 3 significant figures,0.20 g has 2 significant figures.(5)When a number ends in zeroes that are notto the right of a decimal point, the zeroes arenot necessarily significant: e.g., 190 milesmay be 2 or 3 significant figures, 50,600calories may be 3, 4, or 5 significant figures.The potential ambiguity in the last rule can be avoided by the use of standard exponential, or "scientific" notation. For example, depending onwhether the number of significant figures is 3, 4, or 5, we would write 50,600 calories as:5.06 × 104 calories (3 significant figures)5.060 ×104calories (4 significant figures), or5.0600 × 104 calories (5 significant figures).2.Rules for rounding off numbers(1)If the digit to be dropped is greater than 5,the last retained digit is increased by one.For example, 12.6 is rounded to 13.(2)If the digit to be dropped is less than 5, thelast remaining digit is left as it is. Forexample, 12.4 is rounded to 12.(3)If the digit to be dropped is 5, and if anydigit following it is not zero, the lastremaining digit is increased by one. Forexample, 12.51 is rounded to 13.(4)If the digit to be dropped is 5 and isfollowed only by zeroes, the last remainingdigit is increased by one if it is odd, but leftas it is if even. For example, 11.5 is roundedto 12, 12.5 is rounded to 12.This rule means that if the digit to be dropped is 5 followed only by zeroes, the result is always rounded to the even digit. The rationale is to avoid bias in rounding: half of the time we round up, half the time we round down.3.Arithmetic using significant figuresIn carrying out calculations, the general rule is that the accuracy of a calculated result is limited by the least accurate measurement involved in the calculation.(1) In addition and subtraction, the result is rounded off to the last common digit occurring furthest to the right in all components. Another way to state this rules, is that, in addition and subtraction, the result is rounded off so that it has the same number of decimal places as the measurement having the fewest decimal places. For example,100 (assume 3 significant figures) + 23.643 (5 significant figures) = 123.643,which should be rounded to 124 (3 significant figures).(2) In multiplication and division, the resultshould be rounded off so as to have the same number of significant figures as in the component with the least number of significant figures. For example,3.0 (2 significant figures ) ×12.60 (4 significant figures) = 37.8000which should be rounded off to 38 (2 significant figures).1.4.3 Scientific NotationScientific notation, also known as standard form or as exponential notation, is a way of writing numbers that accommodates values too large or small to be conveniently written in standard decimal notation.In scientific notation all numbers are written like this:a × 10b("a times ten to the power of b"), where the exponent b is an integer, and the coefficient a is any real number, called the significant or mantissa (though the term "mantissa" may cause confusion as it can also refer to the fractional part of the common logarithm). If the number is negative then a minus sign precedes a (as in ordinary decimal notation).In standard scientific notation the significant figures of a number are retained in a factor between 1 and 10 and the location of the decimal point is indicated by a power of 10. For example:An electron's mass is about 0.00000000000000000000000000000091093822 kg. In scientific notation, this is written 9.1093822×10−31 kg.The Earth's mass is about 5973600000000000000000000 kg. In scientific notation, this is written 5.9736×1024 kg.1.5 Units of Measurement1.5.1 Systems of Measurement1.United States Customary System (USCS)The United States customary system (also called American system) is the most commonly used system of measurement in the United States. It is similar but not identical to the British Imperial units. The U.S. is the only industrialized nation that does not mainly use the metric system in its commercial and standards activities. Base units are defined butseem arbitrary (e.g. there are 12 inches in 1 foot)2.MetricThe metric system is an international decimalized system of measurement, first adopted by France in 1791, that is the common system of measuring units used by most of the world. It exists in several variations, with different choices of fundamental units, though the choice of base units does not affect its day-to-day use. Over the last two centuries, different variants have been considered the metric system. Metric units are universally used in scientific work, and widely used around the world for personal and commercial purposes. A standard set of prefixes in powers of ten may be used to derive larger and smaller units from the base units.3.SISI system (for Système International) was adopted by the International Bureau of Weights and Measures in 1960, it is a revision and extension of the metric system. Scientists and engineers throughout the world in all disciplines are now being urged to use only the SI system of units.1.5.2 SI base unitsThe SI is founded on seven SI base units for seven base quantities assumed to be mutually independent, as given in Table 1.1.Table 1.1 SI Base Physical Quantities and UnitsU n i tN a m e UnitSymbolBaseQuantityQuantitySymbolDimensionSymbolm m l l Le t e r e n g t hk i lo g r a m kgmassm Ms ec o nd stimet Ta mp e r e AelectriccurrentI Ik el v i n KthermodynTΘm i ct e m p e r a t u r em o l e molamountofsubstancen Nc an d e l a cdluminousIvJntensity1.5.3 SI derived unitsOther quantities, called derived quantities, aredefined in terms of the seven base quantities via asystem of quantity equations. The SI derived unitsfor these derived quantities are obtained from theseequations and the seven SI base units. Examples ofsuch SI derived units are given in Table 1.2, where itshould be noted that the symbol 1 for quantities ofdimension 1 such as mass fraction is generallyomitted.Table 1.2 SI Derived Physical Quantities and(symbol) Unit(symbol)UArea (A) squaremeterm V olume (V) cubicmeterm Density (ρ) kilogramper cubicmeterkVelocity (u) meterpersecondmPressure (p) pascal(Pa)kEnergy (E) joule (J) (k Frequency (ν) hertz(Hz)1Quantity of electricity (Q) coulomb(C)AElectromotive force (E) volt (V) (kmsForce (F) newton(N)kFor ease of understanding and convenience, 22SI derived units have been given special names andsymbols, as shown in Table 1.3.Table 1.3 SI Derived Units with special names andsymbolsD e r i v e dq u a n t i t y SpecialnameSpecialSymbolExpressionintermsofotherSIunitsSIbaseunitsp r r ml a n ea n g l e adianad·m-1=1s o l i da n g l e steradiansrm2·m-2=1f r e q u e n c y hertzHzs-1f o r c e newtonN m·kg·s-2p p P N mr e s s u r e ,s t r e s s ascala/m21·kg·s-2e n e r g y ,w o r k ,q u a n t i t yo fh e a jouleJ N·mm2·kg·s-2p o w e r ,r a d i a n tf l u x wattW J/sm2·kg·s-3e l e c t r i cc h a r g e q u a n t i t y coulombC s·Afe l e c t r i c i t ye l e c t r i cp o t e n t i a l ,p o t e n t i a l voltV W/Am2·kg·s-3·A-1i f f e r e n c e ,e l e c t r o m o t i v ef o r c ec a p a c i t a n c e faradF C/Vm-2·kg-1·s 4·A 2e l e c t r i cr e s i s t a n c e ohmΩV/Am2·kg·s-3·A-2e l e c t r i cc o nd u c t a n c siemensS A/Vm-2·kg-1·s2·Aem a g n e t i cf l u x weberWbV·sm2·kg·s-2·A-1m a g n e t i cf l u xd e n s i t y teslaT Wb/m2kg·s-2·A-1i n d henH Wb/m2u c t a n c e ryA ·kg·s-2·A-2C e l s i u st e m p e r a t u r e degreeCelsius°CKl u m i n o u s lumenlmcd·srcd·srl u xi l l u m i n a n c e luxlxlm/m2m-2·cd·sra c t i v i t y( o far a d i o n u c l i d e becquerelBqs-1a b s o r b e dd o se ,s p e c i f i ce n e r g y( i m p a r t e d ) ,grayGyJ/kgm2·s-2e r m ad o s ee q u i v a l e n t ,e ta l .sievertSvJ/kgm2·s-2c a t a l y t i ca c t i v i katalkats-1·molyCertain units that are not part of the SI are essential and used so widely that they are accepted by the CIPM (Commission Internationale des Poids Et Mesures) for use with the SI. Some commonly used units are given in Table 1.4.Table 1.4 Non-SI units accepted for use with theSIN a m e SymbolQuantityEquivalentSIunitmi n u t e mintime1min=6sho u r htime1h6min=36s da y dtime1d=24h=144min=864sdegreeo fa r c °planeangle1°=(π/18)radm i n u t eo fa r c ′planeangle1′=(1/6)°=(π/18radsecondo fa r c ″planeangle1″=(1/6)′=(1/36)°=(π/648)rdhect a r e haarea1ha=1a=1m²l i t r e lorLvolume1l=1dm3=.1m3ton n e tmass1t=13kg=1MgThe 20 SI prefixes used to form decimal multiples and submultiples of SI units are given in Table 1.5.Table 1.5 SI PrefixesF a c t o r NameSymbolFactorNameSymbol1 0 24yottaY 1-1decid1 0 21zettZ 1-2centc。
尼尔斯·玻尔（2）神秘的电子
尼尔斯·玻尔（2）神秘的电⼦Niels Bohr 尼尔斯·玻尔2．Mysterious Electronics神秘的电⼦博主改写英语原⽂并翻译成汉语，对照发帖于此，供⽹友参考。
The atom is accepted as the smallest particle of matter. There can be atoms of copper, for example, or of neon or of uranium or of any element. ⼈们普遍认为：原⼦是物质的最⼩颗粒。
⽐如，可能有铜原⼦存在，或者氖原⼦，或者铀原⼦，或者任何元素的原⼦存在。
Theoretically these materials can be divided and divided into smaller and smaller pieces; but no matter how small the pieces get （1）— even down to the single atom — they can still be recognized as copper or neon or uranium or whatever element. But divide the atom and the material is no longer the same element but something else. (2) 从理论上讲，这些物质可以被分裂，再被分裂，分裂成越来越⼩的颗粒；但是，不管这些颗粒变得多么⼩—甚⾄⼩到单个的原⼦—它们仍然可以被鉴别为是铜、或者氖，或者铀，或者其他什么元素。
但是，如果分裂原⼦，那这种物质便不再是原来那种物质的元素，⽽是其他东西了。
The atom itself is made up of two main parts. A central part is called the nucleus. Particles, which are separated from this nucleus, are called electrons. 原⼦本⾝由两个主要部分构成。
1 Atoms
Subatomic Particles and Atomic Structure Researches discovered that like charges repel each other, and opposite charges attract one another.
2.2 Subatomic Particles and Atomic Structure
In the late 1800’s, many scientists were doing research involving radiation, the emission and transmission of energy in the form of waves.
RБайду номын сангаасtherford proposed a new model for the atom:
Positive charge is concentrated in the nucleus.
The nucleus accounts for most of an atom’s mass and is an extremely dense central core within the atom. ➢A typical atomic radius is about 100 pm ➢A typical nucleus has a radius of about 5×10–3 pm ➢1 pm = 1×10–12 m
材料科学基础-第2章晶体缺陷
12
12
2.1.4 过饱和点缺陷
晶体中的点缺陷浓度可能高于平衡浓度，称为过饱和点 缺陷，或非平衡点缺陷。获得的方法：
7
7
2.1.1 分类
3.置换原子（Substitutional atom） 异类原子代换了原有晶体中的原子，而处于晶体点阵的结
点位置，称为置换原子，亦称代位原子。 各种点缺陷，都破坏了原有晶体的完整性。它们从电学
和力学这两个方面，使近邻原子失去了平衡。空位和直 径较小的置换原子，使周围原子向点缺陷的方向松弛， 间隙原子及直径较大的置换原子，把周围原子挤开一定 位置。因而在点缺陷的周围，就出现了一定范围的点阵 畸变区，或称弹性应变区。距点缺陷越远，其影响越小 。因而在每个点缺陷的周围，都会产生一个弹性应力场 。
例题 2-1 解答
The lattice parameter of FCC copper is 0.36151 nm. The basis is 1, therefore, the number of copper atoms, or lattice points, per cm3 is:
n(3.64a1 t5 1 o 1 8 0 m cm )3 s /c8.4 e 7 l1 l 202 copap to em r3 s/
Or, there should be 2.00 – 1.9971 = 0.0029 vacancies per unit cell. The number of vacancies per cm3 is:
翻译(排序版)核专业英语~nuclear energy
A字开头A complete understanding of the microscopic structure of matter (物质微观结构) and the exact nature of the forces acting(作用力的准确性质) is yet to (有待于) be realized. However, excellent models have been developed to predict behavior to an adequate degree of accuracy for most practical purposes. These models are descriptive (描述的) or mathematical often based on analogy (类推) with large-scale process, on experimental data (实验数据), or on advanced theory.对物质的微观结构和作用力的准确性质的完全认识仍有待于实现。
然而，为了实际的用途，能足够精确地预知物质在微观世界行为的模型已经被研究出来。
这些模型是描述性的或数学的，基于对大尺度过程的类推、实验数据或先进的理论。
A nucleus can get rid of excess internal energy by the emission of a gamma ray, but in analternate process called internal conversion, the energy is imparted directly to one of the atomic electrons, ejecting it from the atom. In an inverse process called K-capture, the nucleus spontaneously absorbs one of its own orbital electrons. Each of these processes is followed by the production of X-rays as the inner shell vacancy is filled.一个原子核能够通过发射g 射线而除去过剩的内能，但在称为内转换的另一个交换过程中，能量直接传给原子中一个电子，使这一电子从原子中被逐出。
大学物理英文版
§1-1 Frame of Reference Particle(质点）
1. Frame of Reference（参照系）
•张达宋 《物理学基本教程》 •李行一等， 《物理学基本教程教学参考书》 •李行一等，《物理学基本教程》习题分析与解答 •张三慧等， 《大学物理学》 •Halliday et.al 《Fundamentals of Physics》 •W. Sears et.al 《University Physics》 •史蒂芬.霍金，《时间简史》 •盛正卯等，《物理学与人类文明》 •B.K.里德雷，《时间、空间和万物》 •…………..
4.Units(单位）
International System of Units(SI: Syst me International d’Unit s 法语） is used in China
mass
m
kg:千克 kilogram
length
L m:米 meter
Time
t s:秒 second
5. Scalar and vector（标量和矢量）: Two types of physical quantities（量）:
教 学基本 要 求
1. 理解描述质点运动物理量的定义及其矢量性、相 对性和瞬时性； 2. 掌握运动方程的物理意义，会用微积分方法求解 运动学两类问题； 3. 掌握平面抛体运动和圆周运动的规律； 4. 理解运动描述的相对性，会用速度合成定理和加 速度合成定理解题。
重要历史人物
材料工程专业英语2原子结构Atomic Structure and Interatomic Bonding
range) below the micrograph.
Why study atomic structure and interatomic
bonding?
An important reason to have an understanding of interatomic bonding in solids is that, in some instances, the type of bond allows us to explain a material’s properties. For example, consider carbon, which may exist as both graphite and diamond. Whereas graphite is relatively soft and has a ‘‘greasy’’ feel to it, diamond is the hardest known material. This dramatic ( significant 显著的) disparity (difference差异) in properties is directly attributable to (归因于) a type of interatomic bonding found in graphite that does not exist in diamond (see Section 3.9).
What should you be able to do after studying this chapter?
Name and explain the primary or chemical bond found in solids.
材料科学与工程专业英语课文 自己整理的 可以打印 匡少平 王世颖 第二版 化学工业出版社
Unit 1Materials are probably more deep-seated in our culture than most of us realize. Transportation, housing, clothing, communication, recreation, and food production— virtually every segment of our everyday lives is influenced to one degree or another by materials. Historically, the development and advancement of societies have been intimately tied to the members’ ability to produce and manipulate materials to fill their needs. In fact, early civilizations have been designated by the level of their materials development (Stone Age, Bronze Age, Iron Age).1The earliest humans had access to only a very limited number of materials, those that occur naturally: stone, wood, clay, skins, and so on. With time they discovered techniques for producing materials that had properties superior to those of the natural ones; these new materials included pottery and various metals. Furthermore, it was discovered that the properties of a material could be altered by heat treatments and by the addition of other substances. At this point, materials utilization was totally a selection process that involved deciding from a given, rather limited set of materials the one best suited for an application by virtue of its characteristics. It was not until relatively recent times that scientists came to understand the relationships between the structural elements of materials and their properties. This knowledge, acquired over approximately the past 100 years, has empowered them to fashion, to a large degree, the characteristics of materials. Thus, tens of thousands of different materials have evolved with rather specialized characteristics that meet the needs of our modern and complex society; these include metals, plastics, glasses, and fibers.The development of many technologies that make our existence so comfortable has been intimately associated with the accessibility of suitable materials. An advancement in the understanding of a material type is often the forerunner to the stepwise progression of a technology. For example, automobiles would not have been possible without the availability of inexpensive steel or some other comparable substitute. In our contemporary era, sophisticated electronic devices rely on components that are made from what are called semiconducting materials.MATERIALS SCIENCE AND ENGINEERINGSometimes it is useful to subdivide the discipline of materials science and engineering into materials science and materials engineering sub disciplines. Strictly speaking, “materials science” involves investigating the relationships that exist between the structures and properties of materials. In contrast, “materials engineering” is, on the basis of these structure–property correlations, designing or engineering the structure of a material to produce a predetermined set of properties.2 From a functional perspective, the role of a materials scientist is to develop or synthesize new materials, whereas a materials engineer is called upon to create new products or systems using existing materials, and/or to develop techniques for processing materials. Most graduates in materials programs are trained to be both materials scientists and materials engineers.“Structure” is at this point a nebulous term that des erves some explanation. In brief, the structure of a materialusually relates to the arrangement of its internal components. Subatomic structure involves electrons within the individual atoms and interactions with their nuclei. On an atomic level, structure encompasses the organization of atoms or molecules relative to one another. The next larger structural realm, which contains large groups of atoms that are normally agglomerated together, is termed “microscopic,” meaning that which is subject to direct o bservation using some type of microscope. Finally, structural elements that may be viewed with the naked eye are termed “macroscopic.”The notion of “property” deserves elaboration. While in service use, all materials are exposed to external stimuli that evoke some type of response. For example, a specimen subjected to forces will experience deformation, or a polished metal surface will reflect light. A property is a material trait in terms of the kind and magnitude of response to a specific imposed stimulus. Generally, definitions of properties are made independent of material shape and size.Virtually all important properties of solid materials may be grouped into six different categories: mechanical, electrical, thermal, magnetic, optical, and deteriorative. For each there is a characteristic type of stimulus capable of provoking different responses. Mechanical properties relate deformation to an applied load or force; examples include elastic modulus and strength. For electrical properties, such as electrical conductivity and dielectric constant, the stimulus is an electric field. The thermal behavior of solids can be represented in terms of heat capacity and thermal conductivity. Magnetic properties demonstrate the response of a material to the application of a magnetic field. For optical properties, the stimulus is electromagnetic or light radiation; index of refraction and reflectivity are representative optical properties. Finally, deteriorative characteristics relate to the chemical reactivity of materials. The chapters that follow discuss properties that fall within each of these six classifications.In addition to structure and properties, two other important components are involved in the science and engineering of materials—namely, “processing” a nd “performance. “With regard to the relationships of these four components, the structure of a material will depend on how it is processed. Furthermore, a material’s performance will be a function of its properties. Thus, the interrelationship between processing, structure, properties, and performance is as depicted in the schematic illustration shown in Figure 1.1. Throughout this text we draw attention to the relationships among these four components in terms of the design, production, and utilization of materialsWHY STUDY MATERIALS SCIENCE AND ENGINEERING?Why do we study materials? Many an applied scientist or engineer, whether mechanical, civil, chemical, or electrical, will at one time or another be exposed to a design problem involving materials. Examples might include a transmission gear, the superstructure for a building, an oil refinery component, or an integrated circuit chip. Of course, materials scientists and engineers are specialists who are totally involved in the investigation and design of materials.Many times, a materials problem is one of selecting the right material from the many thousands that are available. There are several criteria on which the final decision is normally based. First of all, the in-service conditions must be characterized, for these will dictate the properties required of the material. On only rare occasions does a materialpossess the maximum or ideal combination of properties. Thus, it may be necessary to trade off one characteristic for another. The classic example involves strength and ductility; normally, a material having a high strength will have only a limited ductility. In such cases a reasonable compromise between two or more properties may be necessary.A second selection consideration is any deterioration of material properties that may occur during service operation. For example, significant reductions in mechanical strength may result from exposure to elevated temperatures or corrosive environments. Finally, probably the overriding consideration is that of economics: What will the finished product cost? A material may be found that has the ideal set of properties but is prohibitively expensive. Here again, some compromise is inevitable. The cost of a finished piece also includes any expense incurred during fabrication to produce the desired shape.The more familiar an engineer or scientist is with the various characteristics and structure–property relationships, as well as processing techniques of materials, the more proficient and confident he or she will be to make judicious materials choices based on these criteria.U n i t2CLASSIFICATION OF MATERIALSSolid materials have been conveniently grouped into three basic classifications: metals, ceramics, and polymers. This scheme is based primarily on chemical makeup anatomic structure, and most materials fall into one distinct grouping or another, although there are some intermediates. In addition, there are the composites, combinations of two or more of the above three basic material classes. Another classification is advanced materials—those used in high-technology applications—viz. semiconductors, biomaterials, smart materials, and nanoengineered materials;MetalsMaterials in this group are composed of one or more metallic elements (such as iron, aluminum, copper, titanium, gold, and nickel), and often also nonmetallic elements (for example, carbon, nitrogen, and oxygen) in relatively small amounts.3 Atoms in metals and their alloys are arranged in a very orderly manner (as discussed in Chapter 3),and in comparison to the ceramics and polymers, are relatively dense (Figure 1.3).With regard to mechanical characteristics, these materials are relatively stiff (Figure 1.4)and strong (Figure 1.5), yet are ductile (i.e., capable of large amounts of deformation without fracture), and are resistant to fracture (Figure 1.6), which accounts for their widespread use in structural applications. Metallic materials have large numbers of nonlocalized electrons; that is, these electrons are not bound to particular atoms .Many properties of metals are directly attributable to these electrons. For example, metals are extremely good conductors of electricity (Figure 1.7) and heat, and are not transparent to visible light; a polished metal surface has a lustrous appearance. In addition, some of the metals (viz., Fe, Co, and Ni) have desirable magnetic properties.CeramicsCeramics are compounds between metallic and nonmetallic elements; they are most frequently oxides, nitrides, and carbides. For example, some of the common ceramic materials include aluminum oxide (or alumina, Al2O3), silicon dioxide (or silica, SiO2), silicon carbide (Sic), silicon nitride (Si3N4), and, in addition, what some refer to as the traditional ceramics—those composed of clay minerals (i.e., porcelain), as well as cement, and glass. With regard to mechanical behavior, ceramic materials are relatively stiff and strong—stiffnesses and strengths are comparable to those of the metals (Figures 1.4 and 1.5). In addition, ceramics are typically very hard. On the other hand, they are extremely brittle (lack ductility), and are highly susceptible to fracture (Figure 1.6). These materials are typically insulative to the passage of heat and electricity (i.e., have low electrical conductivities, Figure 1.7), and are more resistant to high temperatures and harsh environments than metals and polymers. With regard to optical characteristics, ceramics may be transparent, translucent, or opaque (Figure1.2), and some of the oxide ceramics (e.g., Fe3O4) exhibit magnetic behavior.PolymersPolymers include the familiar plastic and rubber materials. Many of them are organic compounds that are chemically based on carbon, hydrogen, and other nonmetallic elements (vision, N, and Si). Furthermore, they have very large molecular structures, often chain-like in nature that have a backbone of carbon atoms. Some of the common and familiar polymers are polyethylene (PE), nylon, poly (vinyl chloride) (PVC), polycarbonate (PC), polystyrene (PS), and silicone rubber. These materials typically have low densities (Figure 1.3), whereas their mechanical characteristics are generally dissimilar to the metallic and ceramic materials—they are not as stiff nor as strong as these other material types (Figures 1.4 and 1.5). However, on the basis of their low densities, many times their stiffness’s and strengths on a per mass basis are comparable to the metals and ceramics. In addition, many of the polymers are extremely ductile and pliable (i.e., plastic), which means they are easily formed into complex shapes. In general, they are relatively inert chemically and unreactive in a large number of environments. One major drawback to the polymers is their tendency to soften and/or decompose at modest temperatures, which, in some instances, limits their use. Furthermore, they have low electrical conductivities (Figure1.7) and are nonmagnetic.CompositesA composite is composed of two (or more) individual materials, which come from the categories discussed above—viz., metals, ceramics, and polymers. The design goal of a composite is to achieve a combination of properties that is not displayed by any single material, and also to incorporate the best characteristics of each of the component materials. A large number of composite types exist that are represented by different combinations of metals, ceramics, and polymers. Furthermore, some naturally-occurring materials are also considered to be composites—for example, wood and bone. However, most of those we consider in our discussions are synthetic (or man-made) composites.ADVANCED MATERIALSMaterials that are utilized in high-technology (or high-tech) applications are sometimes termed advanced materials.By high technology we mean a device or product that operates or functions using relatively intricate and sophisticated principles; examples include electronic equipment (camcorders, CD/DVD players, etc.), computers, fiber-optic systems, spacecraft, aircraft, and military rocketry. These advanced materials are typically traditional materials whose properties have been enhanced, and, also newly developed, high-performance materials. Furthermore, they may be of all material types (e.g., metals, ceramics, polymers), and are normally expensive. Advanced materials include semiconductors, biomaterials, and what we may term “materials of the future” (that is, smart materials and Nan engineered materials) SemiconductorsSemiconductors have electrical properties that are intermediate between the electrical conductors (viz. metals and metal alloys) and insulators (viz. ceramics and polymers)—Figure 1.7. Furthermore, the electrical characteristics of these materials are extremely sensitive to the presence of minute concentrations of impurity atoms, for which the concentrations may be controlled over very small spatial regions. Semiconductors have made possible the advent of integrated circuitry that has totally revolutionized the electronics and computer industries (not to mention our lives) over the past three decades.BiomaterialsBiomaterials are employed in components implanted into the human body for replacement of diseased or damaged body parts. These materials must not produce toxic substances and must be compatible with body tissues (i.e., must not cause adverse biological reactions). All of the above materials—metals, ceramics, polymers, composites, and semiconductors—may be used as biomaterials. For example, some of the biomaterials that are utilized in artificial hip replacementsMaterials of the FutureSmart MaterialsSmart (or intelligent) materials are a group of new and state-of-the-art materials now being developed that will have a significant influence on many of our technologies. The adjective “smart” implies that these materials are able to sense changes in their environments and then respond to these changes in predetermined manners—traits that are also found in living organisms. In addition, this “smart” concept is being extended to rather sophisticated systems that consist of both smart and traditional materials. Components of a smart material (or system) include some type of sensor (that detects an input signal), and an actuator (that performs a responsive and adaptive function). Actuators may be called upon to change shape, position, natural frequency, or mechanical characteristics in response to changes in temperature, electric fields, and/or magnetic fields. Four types of materials are commonly used for actuators: shape memory alloys, piezoelectric ceramics, magnetostrictive materials, and electrorheological/magnetorheological fluids. Shape memory alloys are metals that, after having been deformed, revert back to their original shapes when temperature is changed (see the Materials of Importance piece following Section 10.9). Piezoelectric ceramics expand and contract in response to an applied electric field (or voltage); conversely, they also generate an electric field when their dimensions are altered (see Section18.25).The behavior of magnetostrictive materials is analogous to that of the piezoelectric, except that they are responsive to magnetic fields. Also, electro rheological and magnetorheological fluids are liquids that experience dramatic changes in viscosity upon the application of electric and magnetic fields, respectively.Materials/devices employed as sensors include optical fibers (Section 21.14), piezoelectric materials (including some polymers), and microelectromechanical devices (MEMS, Section 13.8).For example, one type of smart system is used in helicopters to reduce aerodynamic cockpit noise that is created by the rotating rotor blades. Piezoelectric sensors inserted into the blades monitor blade stresses and deformations; feedback signals from these sensors are fed into a computer-controlled adaptive device, which generates noise-canceling antinomies.Nanoengineered MaterialsUntil very recent times the general procedure utilized by scientists to understand the chemistry and physics of materials has been to begin by studying large and complex structures, and then to investigate the fundamental building blocks of these structures that are smaller and simpler. This approach is sometimes termed “top down “science. However, with the advent of scanning probe microscopes (Section4.10), which permit observation of individual atoms and molecules, it has become possible to manipulate and move atoms and molecules to form new structures and, thus, design new materials that are built from simple atomic-level constituents(i.e., “materials by design”). This ability to carefully arrange atoms provides opportunities to develop mechanical, electrical, magnetic, and other properties that are not otherwise possible. We call this the “bottom-up” approach, and the study of the properties of these materials is termed “nanotechnology”; the “nan” prefix denotes that the dimensions of these structural entities are on the order of a nanometer (10_9 m)—as a rule, less than 100 nanometers (equivalent to approximately 500atom diameters).5 One example of a material of this type is the carbon nanotube, discussed in Section 12.4. In the future we will undoubtedly find that increasingly more of our technological advances will utilize these nanengineered materials.Unit 4Physical properties are those that can be observed without changing the identity of the substance. The general properties of matter such as color, density, hardness, are examples of physical properties. Properties that describe how a substance changes into a completely different substance are called chemical properties. Flammability andcorrosion/oxidation resistance are examples of chemical properties.The difference between a physical and chemical property is straightforward until the phase of the material is considered. When a material changes from a solid to a liquid to a vapor it seems like them become a difference substance. However, when a material melts, solidifies, vaporizes, condenses or sublimes, only the state of the substance changes.Consider ice, liquid water, and water vapor, they are all simply H2O. Phase is a physical property of matter and matter can exist in four phases – solid, liquid, gas and plasma.Some of the more important physical and chemical properties from an engineering material standpoint will be discussed in the following sections.•Phase Transformation Temperatures•Density•Specific Gravity•Thermal Conductivity•Linear Coefficient of Thermal Expansion•Electrical Conductivity and Resistivity•Magnetic Permeability•Corrosion ResistancePhase Transformation TemperaturesWhen temperature rises and pressure is held constant, a typical substance changes from solid to liquid and then to vapor. Transitions from solid to liquid, from liquid to vapor, from vapor to solid and visa versa are called phase transformations or transitions. Since some substances have several crystal forms, technically there can also be solid to another solid form phase transformation.Phase transitions from solid to liquid, and from liquid to vapor absorb heat. The phase transition temperature where a solid changes to a liquid is called the melting point. The temperature at which the vapor pressure of a liquid equals 1 atm (101.3 kPa) is called the boiling point. Some materials, such as many polymers, do not go simply from a solid to a liquid with increasing temperature. Instead, at some temperature below the melting point, they start to lose their crystalline structure but the molecules remain linked in chains, which results in a soft and pliable material. The temperature at which a solid, glassy material begins to soften and flow is called the glass transition temperature.DensityMass can be thinly distributed as in a pillow, or tightly packed as in a block of lead. The space the mass occupies is its volume, and the mass per unit of volume is its density.Mass (m) is a fundamental measure of the amount of matter. Weight (w) is a measure of the force exerted by a mass and this force is force is produced by the acceleration of gravity. Therefore, on the surface of the earth, the mass of an object is determined by dividing the weight of an object by 9.8 m/s2 (the acceleration of gravity on the surface of the earth). Since we are typically comparing things on the surface of the earth, the weight of an object is commonly used rather than calculating its mass.The density (r) of a material depends on the phase it is in and the temperature. (The density of liquids and gases is very temperature dependent.) Water in the liquid state has a density of 1 g/cm3 = 1000kg/m3 at 4o C. Ice has a density of 0.917 g/cm3 at 0o c, and it should be noted that this decrease in density for the solid phase is unusual. For almost all other substances, the density of the solid phase is greater than that of the liquid phase. Water vapor (vapor saturated air) has a density of 0.051 g/cm3.Some common units used for expressing density are grams/cubic centimeter, kilograms/cubic meter, grams/milliliter, grams/liter, pounds for cubic inch and pounds per cubic foot; but it should be obvious that any unit of mass per any unit of volume can be used.Substance Density(g/cm3)Air 0.0013Gasoline 0.7Wood 0.85Water (ice) 0.92Water (liquid) 1.0Aluminum 2.7Steel 7.8Silver 10.5Lead 11.3Mercury 13.5Gold 19.3Specific GravitySpecific gravity is the ratio of density of a substance compared to the density of fresh water at 4°C (39° F). At this temperature the density of water is at its greatest value and equal 1 g/mL. Since specific gravity is a ratio, so it has no units. An object will float in water if its density is less than the density of water and sink if its density is greater that that ofwater. Similarly, an object with specific gravity less than 1 will float and those with a specific gravity greater than one will sink. Specific gravity values for a few common substances are: Au, 19.3; mercury, 13.6; alcohol, 0.7893; benzene, 0.8786. Note that since water has a density of 1 g/cm3, the specific gravity is the same as the density of the material measured in g/cm3.Magnetic PermeabilityMagnetic permeability or simply permeability is the ease with which a material can be magnetized. It is a constant of proportionality that exists between magnetic induction and magnetic field intensity. This constant is equal to approximately 1.257 x 10-6 Henry per meter (H/m) in free space (a vacuum). In other materials it can be much different, often substantially greater than the free-space value, which is symbolized µ0.Materials that cause the lines of flux to move farther apart, resulting in a decrease in magnetic flux density compared with a vacuum, are called diamagnetic. Materials that concentrate magnetic flux by a factor of more than one but less than or equal to ten are called paramagnetic; materials that concentrate the flux by a factor of more than ten are called ferromagnetic. The permeability factors of some substances change with rising or falling temperature, or with the intensity of the applied magnetic field.In engineering applications, permeability is often expressed in relative, rather than in absolute, terms. If µ o represents the permeability of free space (that is, 4p X10-7H/m or 1.257 x 10-6 H/m) and µ represents the permeability of the substance in question (also specified in henrys per meter), then the relative permeability, µr, is given by:µr = µ / µ0For non-ferrous metals such as copper, brass, aluminum etc., the permeability is the same as that of "free space", i.e. the relative permeability is one. For ferrous metals however the value of µ r may be several hundred. Certain ferromagnetic materials, especially powdered or laminated iron, steel, or nickel alloys, have µr that can range up to about 1,000,000. Diamagnetic materials have µr less than one, but no known substance has relative permeability much less than one. In addition, permeability can vary greatly within a metal part due to localized stresses, heating effects, etc.When a paramagnetic or ferromagnetic core is inserted into a coil, the inductance is multiplied by µr compared with the inductance of the same coil with an air core. This effect is useful in the design of transformers and eddy current probes.Unit 5The mechanical properties of a material are those properties that involve a reaction to an applied load. The mechanical properties of metals determine the range of usefulness of a material and establish the service life that can be expected. Mechanical properties are also used to help classify and identify material. The most common properties considered are strength, ductility, hardness, impact resistance, and fracture toughness.Most structural materials are anisotropic, which means that their material properties vary with orientation. The variation in properties can be due to directionality in the microstructure (texture) from forming or cold working operation, the controlled alignment of fiber reinforcement and a variety of other causes. Mechanical properties are generally specific to product form such as sheet, plate, extrusion, casting, forging, and etc. Additionally, it is common to see mechanical property listed by the directional grain structure of the material. In products such as sheet and plate, the rolling direction is called the longitudinal direction, the width of the product is called the transverse direction, and the thickness is called the short transverse direction. The grain orientations in standard wrought forms of metallic products are shown the image.The mechanical properties of a material are not constants and often change as a function of temperature, rate of loading, and other conditions. For example, temperatures below room temperature generally cause an increase in strength properties of metallic alloys; while ductility, fracture toughness, and elongation usually decrease. Temperatures above room temperature usually cause a decrease in the strength properties of metallic alloys. Ductility may increase or decrease with increasing temperature depending on the same variablesIt should also be noted that there is often significant variability in the values obtained when measuring mechanical properties. Seemingly identical test specimen from the same lot of material will often produce considerable different results. Therefore, multiple tests are commonly conducted to determine mechanical properties and values reported can be an average value or calculated statistical minimum value. Also, a range of values are sometimes reported in order to show variability.LoadingThe application of a force to an object is known as loading. Materials can be subjected to many different loading scenarios and a material’s performance is dependant on the loading conditions. There are five fundamental loadin g conditions; tension, compression, bending, shear, and torsion. Tension is the type of loading in which the two sections of material on either side of a plane tend to be pulled apart or elongated. Compression is the reverse of tensile loading and involves pressing the material together. Loading by bending involves applying a load in a manner that causes a material。
chapter_2_chemical_principles
Chapter 2Chemical PrinciplesLearning Objectives1. Know the structure of an atom and its relation to the chemical properties of elements2. Define ionic bond, covalent bond, hydrogen bond, molecular weights, and mole.3. Diagram three basic types of chemical reactions.4. Identify the role of enzymes in chemical reactions.5. List several properties of water that are important to living systems.6. Define acid, base, salt, and pH.7. Distinguish between organic and inorganic compounds.8. Identify by general structure the building blocks of carbohydrates, simple lipids, phospholipids,proteins, and nucleic acids.9. Identify the role of ATP in cellular activities.Introduction1. The science of the interaction between atoms and molecules is called chemistry.2. The metabolic activities of microorganisms involve complex chemical reactions.3. Nutrients are broken down by microbes to obtain energy and to make new cells.The Structure of Atoms1. Atoms are the smallest units of chemical elements that enter into chemical reactions.2. Atoms consist of a nucleus, which contains protons and neutrons, and electrons that move around thenucleus (Text, Fig. 2.1).3. The atomic number is the number of protons in the nucleus; the total number of protons and neutrons isthe atomic weight (Text, Fig. 2.1).Chemical Elements1. Atoms with the same number of protons and the same chemical behavior are classified as the samechemical element.2. Chemical elements are designated by abbreviations called chemical symbols.3. About 26 elements are commonly found in living cells.4. Twelve of those are considered the elements of life. (Text, Table 2.1).5. Atoms that have the same atomic number (same element) but different weights are called isotopes.6. Isotopes of elements with extra neutrons are unstable and can emit radiation. We can detect thisradiation. That enables us to monitor into what structures a cell puts an element when it is fed theradioactive element. We assume that the radioactive element is metabolized in the same manner as the non-radioactive isotope of the same element. For example, radioactive sulfur often can be found inproteins of cells when fed radioactive sulfur (in the amino acids methionine and cysteine).Electronic Configurations1. In an atom, electrons are arranged around the nucleus in electron shells (Text, Fig.2.1).2. Each shell can hold a characteristic maximum number of electrons.3. The chemical properties of an atom are largely due to the number of electrons in its outermost shell, i.e., how easily these outer electrons can be received, donated, or shared.HOW ATOMS FORM MOLECULES: CHEMICAL BONDSChemical Bonds1. Molecules are made up of two or more atoms; molecules consisting of at least two different kinds ofatoms are called compounds.2. Atoms form molecules in order to fill their outermost electron shells or empty them or share theelectron with others to achieve maximum stability. Electrons like to be in pairs (See Table 2.2.).3. Attractive forces that bind the atomic nuclei of two atoms together are called chemical bonds.4. The combining capacity of an atom - the number of chemical bonds the atom can form with otheratoms - is its valence.Ionic Bonds1. A positively or negatively charged atom or group of atoms is called an ion (Text, Fig.2.2).2. A chemical attraction between ions of opposite charge is called an ionic bond.3. To form an ionic bond, one ion is an electron donor and the other ion is an electron acceptor. Thedonated electron finds itself almost exclusively associated with the accepting ion.Covalent Bonds1. In a covalent bond, atoms share pairs of electrons (Text Fig.2.3). The electron spends almost equalamounts of time associated with each atom.2. Covalent bonds are stronger than ionic bonds and are far more common in organisms.3. Would there be solid life structures with just ionic bonds?Hydrogen Bonds1. A hydrogen bond exists when a hydrogen atom covalently bonded to one oxygen or nitrogen atom isattracted to another oxygen or nitrogen atom (Text Fig. 2.4).2. Hydrogen bonds form weak links between different molecules or between parts of the same largemolecule.Molecular Weight and Moles1. The molecular weight is the sum of the atomic weights of all the atoms in a molecule.2. A mole of an atom, ion, or molecule is equal to its atomic or molecular weight expressed in grams. Chemical Reactions1. Definition: Chemical reactions are the making or breaking of chemical bonds between atoms.2. Find out how chemical reactions catalyzed by microbes can destroy precious works of art or can helppreserve works of art.r Additional Readings: "The Microbiology of Art". Bernard Dixon. 2005. ASM News. 71(5):212-213. Copyrighted by ASM and reproduced with permission from ASM.Energy in Chemical Reactions1. A change of energy occurs during chemical reactions.2. Endergonic reactions require energy; exergonic reactions release energy.3. In a synthesis reaction, atoms, ions, or molecules are combined to form a larger molecule.4. (A + B A B)5. In a decomposition reaction, a larger molecule is broken down into its component molecules, ions, oratoms.6. (AB A + B)7. In an exchange reaction, two molecules are decomposed, and their subunits are used to synthesize twonew molecules.8. (AB + CD AC + BD)9. The products of reversible reactions can readily revert back to form the original reactants.How Chemical Reactions Occur1. For a chemical reaction to take place, the reactants must collide with each other.2. The minimum collision energy that can produce a chemical reaction is called its activation energy.3. Specialized proteins called enzymes accelerate chemical reactions in living systems by lowering theactivation energy.Inorganic Compounds1. Inorganic compounds are usually small, ionically bonded molecules.2. Water and many common acids, bases, and salts are examples of inorganic compounds.Water1. Water is the most abundant substance in cells.2. Because water is a polar molecule, it is an excellent solvent (Fig. 2.5).3. Water is a reactant in many of the decomposition reactions of digestion.4. Water is an excellent temperature buffer.Acids, Bases, and Salts (Text, Fig. 2.6)1. An acid dissociates into H+ ions and anions.2. A base dissociates into OH- ions and cations.3. A salt dissociates into negative and positive ions, neither of which is H+ or OH-.Acid-Base Balance1. The term pH refers to the concentration of H+ in a solution.2. A solution with a pH of 7 is neutral; a pH below 7 indicates acidity; a pH above 7 indicates alkalinity.3. A pH buffer, which stabilizes the pH inside a cell, can be used in culture media.4. Most living things grow best near neutral pH. (See Text, pH scale, Fig.2.7)Organic Compounds1. Organic compounds always contain carbon and hydrogen, i.e., CH4 = methane.2. Carbon atoms form up to four bonds with other atoms.3. Organic compounds are mostly or entirely covalently bonded, and many of them are large molecules. Structure and Chemistry1. A chain of carbon atoms forms a carbon skeleton.2. Functional groups of atoms are responsible for most of the properties of organic molecules.3. The letter R may be used to denote the remainder of an organic molecule (See Table 2.3).4. Frequently encountered classes of molecules are R-OH (alcohols), R-COOH (organic acids), H2N-R-COOH (amino acids).5. Small organic molecules may combine into very large molecules called macromolecules.6. Monomers usually bond together by dehydration synthesis or condensation reactions that form waterand a polymer.7. Organic molecules may be broken down by hydrolysis, a reaction involving the splitting of watermolecules and the organic compound.Important Biological MoleculesI-Carbohydrates1. Carbohydrates are compounds consisting of atoms of carbon, hydrogen, and oxygen, with hydrogenand oxygen in a 2:1 ratio (Text, Fig. 2.8).2. Carbohydrates include sugars and starches.3. Carbohydrates can be classified as monosaccharides (simple sugar), disaccharides (two sugars bondedtogether, i.e., sucrose - table sugar), and polysaccharides (more than two sugars bonded together, i.e., starch).4. Monosaccharides contain from three to seven carbon atoms.5. Isomers are two molecules with the same chemical formula but different structures and properties-forexample, glucose (C6H12O6) and fructose (C6H12O6).6. Monosaccharides may form disaccharides and polysaccharides by dehydration synthesis.7. An Important covalent bond that holds two or more sugars together = glycosidic bond.II-Lipids1. Lipids are a diverse group of compound and are insoluble in water (Text, Fig.2.9).2. Building blocks of lipids are glycerol and fatty acids.3. Simple lipids (fats) consist of a molecule of glycerol and three molecules of fatty acids.4. A saturated lipid has no double bonds between carbon atoms in the fatty acids; an unsaturated lipid hasone or more double bonds. Saturated lipids have higher melting points than unsaturated lipids.5. Phospholipids are complex lipids consisting of glycerol, two fatty acids, and a phosphate group (Text,Fig. 2.10).6. An important covalent bond that holds the glycerol subunit to the fatty acid chain is an ester bond inbacteria or an ether bond in archaebacteria.7. Steroids have carbon ring structures and sterols have a functional hydroxyl group (Fig. 2.11).8. Although steroids are not lipids, they are associated with lipids in cell membranes.III-Proteins1. Amino acids are the building blocks of proteins.2. Amino acids consist of carbon, hydrogen, oxygen, nitrogen, and sometimes sulfur (Fig. 2.12).3. Twenty amino acids occur naturally (Text, Table 2.4).4. By linking amino acids, peptide bonds (formed by dehydration synthesis) allow the formation ofpolypeptide chains.5. Proteins have four levels of structure: primary (sequence of amino acids), secondary (regular coils orpleats), tertiary (overall three-dimensional structure of a polypeptide), and quaternary (two or morepolypeptide chains) (Text, Fig. 2.15).6. Conjugated proteins consist of amino acids combined with other organic or inorganic compounds.7. An important covalent bond holding two amino acids together to form a peptide = peptide bond (Fig.2.14).IV-Nucleic Acids1. Nucleic acids-DNA and RNA-are macromolecules consisting of repeating nucleotides.2. The basic building block of nucleic acids is a nucleotide. It is composed of a pentose, a phosphategroup, and a nitrogenous base. Nucleotides without a phosphate group are called nucleosides, which are composed of a pentose and a nitrogenous base.3. A nitrogenous base may be either a pyrimidine or a purine.4. A DNA nucleotide consists of deoxyribose (a pentose) and one of the following nitrogenous bases:thymine or cytosine (pyrimidines), or adenine or guanine (purines) an a phosphate group (Text, Fig.2.16).5. A molecule of DNA consists of two strands of nucleotides wound in a double helix. The strands areheld together by hydrogen bonds between purine and pyrimidine nucleotides and are consideredantiparallel to one another. The following base pairing always occurs between the two strands: AT and GC.6. An RNA nucleotide consists of ribose (a pentose) and one of the following nitrogenous bases: cytosine,guanine, adenine, or uracil Fig. 2.17) and a phosphate group. The following base pairing always occurs between a strand of RNA and another strand of nucleic acid: UA and GC.7. Genes consist of sequences of nucleotides that code for a protein product or for special RNAs (tRNA orrRNA).8. An important high-energy covalent bond holding two phosphate groups together in nucleotides is aphosphodiester bond.Adenosine Triphosphate (ATP)1. ATP stores chemical energy for various cellular activities. It is the energy currency of the cell (Text,Fig. 2.18)2. When the bond to ATP's terminal phosphate group is broken, energy is released.3. The energy from decomposition reactions is used to regenerate ATP from ADP and inorganicphosphate.Additional Readings Appendix1. "The Microbiology of Art". Bernard Dixon. 2005. ASM News. 71(5): 212-213. Copyrighted by ASMand reproduced with permission from ASM.。
重庆理工大学材料科学基础双语翻译第2章翻译-R1
Review回顾复习
Please cite引用 the four components部分 for materials 材料 science and engineering discipline工程科学.
Fundamentals of Materials Science andhemical element 化学元素is characterized by (的特点) the number of protons in the nucleus 原子核, or the atomic number (Z) (原子序数). The atomic mass (A) (原子质量) of a specific 特 殊的atom may be expressed as 被表示成the sum 总数 of the masses of大多数 protons and neutrons 中子within the nucleus. Thus atoms of some elements基础 have two or more different atomic masses, which are called isotopes (同位素).
Fundamentals of Materials Science and Engineering
What should you be able to do after studying this chapter?
Name and explain the primary or chemical bond 化学键found in向 提供 solids固体.
Fundamentals of Materials Science and Engineering
立体化学chapter 2
2.1 Basic Concepts and Principles
Several types of isomerism Including constitutional, configurational, and conformational isomerism.
Constitutional isomers (structural isomers) Molecules with the same atomic composition but different bonding arrangements between atoms. Differ in the order in which the atoms are connected so they contain different functional groups and / or bonding patterns
2.1 Basic Concepts and Principles
Practice:
2. Draw formulae of all possible isomers which have the empirical formula C3H6O.
O
S
O CH3
R
O OH H3C C H 3C CH 3 H3C D CH 2
2.1 Basic Concepts and Principles
2.1 Basic Concepts and Principles
Geometric isomers Configurational isomers that differ in the spatial position around a bond with restricted rotation (e.g. a double bond)
化学常用英文单词汇总
chapter 1 atomic structureelement n.元素all know materials can be broken down into fundamental substances we call element. 我们所知道的所有物质都可以分解成原子。
atom n.原子atom is the smallest particle of matter having all that element’s characteristics.原子时具有元素性质的最小粒子。
nucleus /’nju:kli?s，’nu?kli?s/ 原子核electron n.电子proton 质子neutron 中子compound n. 化合物：When two or more elements combine and form a compound, a chemical change takes place.当两种或两种以上的元素结合形成化合物时, 发生化学变化。
化学中的物质分为单质和化合物，大部分元素是以化合物的形式存在的。
ion n. 离子：when an atom get or lost elections,it becomes ion.原子得失电子后形成离子。
cathode n. 阴极（negative electrode）Cathode rays are attracted by a positive charge.阴极射线被阳电荷所吸引。
anode n. 阳极（positive election）A red wire is often attached to the anode.红色电线通常与阳极相联。
particle n. 粒子：微小粒子包Particles include moleculars,atoms , protons, neutrons ,electrons and ions.括分子，原子，质子，中子，电子，离子等等。
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2.3 THE ATOM AND LIGHT(原子与光 原子与光) 原子与光
Until the 20th century the internal structure of atoms was unknown, but it was believed that electric charge (电荷 电荷) 电荷 and mass were uniform (统一的 Rutherfor performed (执 统一的). 统一的 执 至关紧要的) 行) some crucial (至关紧要的 experiments in which gold 至关紧要的 atoms were bombarded by charged particles. He deduced (推断 1911 that most of the mass and positive charge 推断)in 推断 正电荷） 集中的) （正电荷） of an atom were concentrated (集中的 in a 集中的 nucleus of radius only about l0-5 times that of the atom, and thus occupying a volume of about 10 - l5 times that of the atom. The new view of atoms paved the way for (为…铺平 为 铺平 道路) 道路 Bohr to find an explanation for the production of light.
The energy of the photon hv is equal to the difference between energies in the two orbits. The smallest orbit has a radius R1 = 0.53 ×l0-l0 m, while the others have 平方) radii increasing as the square (平方 of integers (called 平方 quantum numbers (量子数 Thus if n is l, 2, 3, . . . , 量子数)). 量子数 the radius of the nth orbit is Rn = n2Rl.
He(Bohr) assumed that the atom consists of a single electron moving at constant speed in a circular orbit about a nucleus --the proton--as sketched in Fig. 2.2. Each particle has an electric charge of l.6×l0-l9 × coulombs, but the proton has a mass that is 1836 times that of the electron. (Figure 2.2 )
The measured (有规则的 distribution of light 有规则的) 有规则的 among the different wavelengths (波长 at a 波长) 波长 certain tempera-ture can be explained by the assumption (假设 that light is in the form of 假设) 假设 photons. These are absorbed and emitted with definite (一定的 amounts of energy E that are 一定的) 一定的 proportional to the frequency ν, according to E= hv, where h is Planck’s constant, 6.63×l0-34 J× sec. For examp1e, the energy corresponding to (相 相 当于) × × 当于 a frequency of 5.l×l014 is (6.63×l0-34) (5.l×1014) = 3.4×l0-19 J, which is seen to be a very × × minute (微小的 amount of energy. 微小的) 微小的
每 单 位 速 度 的 分 子 个 数
速度 v
图 2.1
分子度分布图
The most probable speed(最概然速率 at the peak of 最概然速率), 最概然速率 Maxwellian distribution (麦克斯韦分布 , is dependent 麦克斯韦分布) 麦克斯韦分布 on temperature according to the relation (关系式 关系式)……. 关系式 The kinetic theory of gas ( 气体动力学 provides a 气体动力学) basis for calculating properties such as the specific heat (比热 比热). 比热 Using the fact from Chapter 1 that the average energy of gas molecules is proportional (成比例的 to the 成比例的) 成比例的 temperature, E = 3 k T , we can deduce (推想 that the 推想), 推想 2 specific heat of a gas consisting only of atoms is c = 3 k m, 2 where m is the mass of one atom.
N=
ρ
M
Na
2.2 GASES (气体 气体) 气体
Substances in the gaseous state (气态) are described approximately by the perfect gas law 理想气体规律(方 程), relating pressure, volume, and absolute temperature (绝对温度), pV=nkT. An increase in the temperature of the gas due to heating causes greater molecular motion, which results in an increase of particle bombardment (n 炮击；轰击) of a container wall and thus of pressure on the wall. The particles of gas, each of mass m, have a variety of speeds v in accord with Maxwell’s gas theory (麦克斯韦 气体理论) as shown in Fig. 2.1.
We can easily find the number of atoms per cubic centimeter (每立方厘米 in a substance if its 每立方厘米) 每立方厘米 density ρ in grams per cubic centimeter is known. This procedure (程序 手续 can be expressed as 程序, 程序 手续) a convenient (便利的 formula for finding N, the 便利的) 便利的 number per cubic centimeter for any material
2.1 ATOMIC THEORY（原子理论） 原子理论）
The most elementary concept (元素概念 is that 元素概念) 元素概念 matter is composed of individual particles (单个粒子 单个粒子) 单个粒子 – atoms – that retain their identity (同一性 特性 as 同一性, 同一性 特性) elements in ordinary physical and chemical interactions. Thus a collection of helium atoms (氦原 (氦原 子) that forms a gas has a total weight that is the sum of the weights of the individual atoms. Also, when two 结合) 化合物) elements combine (结合 to form a compound (化合物 结合 化合物 (e.g., if carbon atoms (碳原子 combine with oxygen 碳原子) 碳原子 atoms (氧原子 to form carbon monoxide molecules 氧原子) 氧原子 (一氧化碳分子 the total weight of the new substance 一氧化碳分子)), 一氧化碳分子 is the sum of the origin elements.
There are more than l00 known elements. Each is given an atomic number (原子序数 in the periodic 原子序数) 原子序数 table of the elements (元素周期表 examples are 元素周期表)– 元素周期表 hydrogen (H) l, helium (He) 2, oxygen (O) 8, and uranium (U) 92. The symbol Z is given to the atomic number, which is also the number of electrons in the atom and determines its chemical properties (性质 性质). 性质 The atomic weight (原子质量 M is the weight in 原子质量) 原子质量 grams of a definite (明确的 number of atoms, 6.02 明确的) 明确的 阿佛伽德罗常 × 1023 , which is Avogadro’s number (阿佛伽德罗常 数), Na.