有机化学英文课件chapter1
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1-12
Electronegativity
Electronegativity:
• a measure of an atom’s attraction for the electrons it shares with another atom in a chemical bond
Pauling scale
H• + • H
H-H H0 = -435 kJ (-104 kcal)/mol
• the shared pair functions in two ways simultaneously; it is shared by the two atoms and fills the valence shell of each atom
3
18
2
8
1
2
h igh er lower
1-5
Electron Configuration of Atoms
Shells are divided into subshells called orbitals, which are designated by the letters s, p, d, f,........
Although all covalent bonds involve sharing of electrons, they differ widely in the degree of sharing
We divide covalent bonds into
• nonpolar covalent bonds • polar covalent bonds
to complete its valence shell; a chemical bond formed by sharing electrons is called a covalent bond • bonds may be partially ionic or partially covalent; these bonds are called polar covalent bonds
• an atom that gains electrons becomes an anion • an atom that loses electrons becomes a cation • the attraction of anions and cations leads to the
formation of ionic solids • an atom may share electrons with one or more atoms
1-6
Electron Configuration of Atoms
Aufbau Principle:
• orbitals fill in order of increasing energy from lowest energy to highest energy
Pauli Exclusion Principle:
• only two electrons can occupy an orbital and their spins must be paired
Hund’s Rule:
• when orbitals of equal energy are available but there are not enough electrons to fill all of them, one electron is added to each orbital before a second electron is added to any one of them
Organic Chemistry
William H. Brown Christopher S. Foote Brent L. Iverson
1-1
Covalent Bonding & Shapes of Molecules
Chapter 1
1-2
Organic Chemistry
The study of the compounds of carbon Over 10 million compounds have been identified
1-11
Lewis Model of Bonding
Atoms bond together so that each atom acquires an electron configuration the same as thatห้องสมุดไป่ตู้of the noble gas nearest it in atomic number
• generally increases left to right in a row • generally increases bottom to top in a column
1-13
Formation of Ions
A rough guideline:
• ions will form if the difference in electronegativity between interacting atoms is 1.9 or greater
1-3
Schematic View of an Atom
• a small dense nucleus, diameter 10-14 - 10-15 m, which contains positively charged protons and most of the mass of the atom
• about 1000 new ones are identified each day!
C is a small atom
• it forms single, double, and triple bonds • it is intermediate in electronegativity (2.5) • it forms strong bonds with C, H, O, N, and some metals
• an extranuclear space, diameter 10-10 m, which contains negatively charged electrons
1-4
Electron Configuration of Atoms
Electrons are confined to regions of space called principle energy levels (shells)
• example: sodium (EN 0.9) and fluorine (EN 4.0) • we use a single-headed (barbed) curved arrow to show
the transfer of one electron from Na to F
••
Na + F ••
D i fference in El ectron eg ati vity Betw een Bo nded Ato ms
Less than 0.5
0.5 to 1.9 Greater than 1.9
Typ e of Bond N on pol ar cov alent Pol ar co valent Io ns f orm
•• ••
••
Na+ F• • ••
• in forming Na+F-, the single 3s electron from Na is transferred to the partially filled valence shell of F
N a(1s22s 22p63s1) + F(1s 22s22p5)
1-7
Electron Configuration of Atoms
The pairing of electron spins
1-8
Electron Configuration of Atoms
Table 1.3 The Ground-State Electron Configuration of Elements 1-18
• we show polarity by using the symbols d+ and d-, or by using an arrow with the arrowhead pointing toward the negative end and a plus sign on the tail of the arrow at the positive end
• each shell can hold 2n2 electrons (n = 1,2,3,4......)
N u mb er of Relative En ergies Electrons S hell of Electrons
S hell Can Hold in Thes e Shells
4
32
Lewis dot structure:
• the symbol of an element represents the nucleus and all inner shell electrons
• dots represent valence electrons
1-10
Lewis Dot Structures
The number of shared pairs
• one shared pair forms a single bond
• two shared pairs form a double bond
• three shared pairs form a triple bond
1-15
Polar and Nonpolar Covalent Bonds
1-9
Lewis Dot Structures
Gilbert N. Lewis Valence shell:
• the outermost occupied electron shell of an atom
Valence electrons:
• electrons in the valence shell of an atom; these electrons are used to form chemical bonds and in chemical reactions
• s (one per shell) • p (set of three per shell 2 and higher) • d (set of five per shell 3 and higher) .....
S hell O rb itals Contain ed in Th at S hell 3 3s , 3px, 3py, 3pz, p lu s five 3d orbitals 2 2s , 2px, 2py, 2pz 1 1s
N a+(1s22s22p6) + F-(1s22s22p6)
1-14
Covalent Bonds
The simplest covalent bond is that in H2
• the single electrons from each atom combine to form an electron pair
1-16
Polar and Nonpolar Covalent Bonds
• an example of a polar covalent bond is that of H-Cl
• the difference in electronegativity between Cl and H is 3.0 - 2.1 = 0.9
Table 1.4 Lewis Dot Structures for Elements 1-18
1A 2A 3A 4A 5A 6A 7A 8A
H.
He :
:: :: ::
.
..
.
.
Li . Be : B : C : .N : :O. : :F : :N e :
.
..
.
.
N a. M g : A l : Si : .P : :S. : :Cl : :A r :
Electronegativity
Electronegativity:
• a measure of an atom’s attraction for the electrons it shares with another atom in a chemical bond
Pauling scale
H• + • H
H-H H0 = -435 kJ (-104 kcal)/mol
• the shared pair functions in two ways simultaneously; it is shared by the two atoms and fills the valence shell of each atom
3
18
2
8
1
2
h igh er lower
1-5
Electron Configuration of Atoms
Shells are divided into subshells called orbitals, which are designated by the letters s, p, d, f,........
Although all covalent bonds involve sharing of electrons, they differ widely in the degree of sharing
We divide covalent bonds into
• nonpolar covalent bonds • polar covalent bonds
to complete its valence shell; a chemical bond formed by sharing electrons is called a covalent bond • bonds may be partially ionic or partially covalent; these bonds are called polar covalent bonds
• an atom that gains electrons becomes an anion • an atom that loses electrons becomes a cation • the attraction of anions and cations leads to the
formation of ionic solids • an atom may share electrons with one or more atoms
1-6
Electron Configuration of Atoms
Aufbau Principle:
• orbitals fill in order of increasing energy from lowest energy to highest energy
Pauli Exclusion Principle:
• only two electrons can occupy an orbital and their spins must be paired
Hund’s Rule:
• when orbitals of equal energy are available but there are not enough electrons to fill all of them, one electron is added to each orbital before a second electron is added to any one of them
Organic Chemistry
William H. Brown Christopher S. Foote Brent L. Iverson
1-1
Covalent Bonding & Shapes of Molecules
Chapter 1
1-2
Organic Chemistry
The study of the compounds of carbon Over 10 million compounds have been identified
1-11
Lewis Model of Bonding
Atoms bond together so that each atom acquires an electron configuration the same as thatห้องสมุดไป่ตู้of the noble gas nearest it in atomic number
• generally increases left to right in a row • generally increases bottom to top in a column
1-13
Formation of Ions
A rough guideline:
• ions will form if the difference in electronegativity between interacting atoms is 1.9 or greater
1-3
Schematic View of an Atom
• a small dense nucleus, diameter 10-14 - 10-15 m, which contains positively charged protons and most of the mass of the atom
• about 1000 new ones are identified each day!
C is a small atom
• it forms single, double, and triple bonds • it is intermediate in electronegativity (2.5) • it forms strong bonds with C, H, O, N, and some metals
• an extranuclear space, diameter 10-10 m, which contains negatively charged electrons
1-4
Electron Configuration of Atoms
Electrons are confined to regions of space called principle energy levels (shells)
• example: sodium (EN 0.9) and fluorine (EN 4.0) • we use a single-headed (barbed) curved arrow to show
the transfer of one electron from Na to F
••
Na + F ••
D i fference in El ectron eg ati vity Betw een Bo nded Ato ms
Less than 0.5
0.5 to 1.9 Greater than 1.9
Typ e of Bond N on pol ar cov alent Pol ar co valent Io ns f orm
•• ••
••
Na+ F• • ••
• in forming Na+F-, the single 3s electron from Na is transferred to the partially filled valence shell of F
N a(1s22s 22p63s1) + F(1s 22s22p5)
1-7
Electron Configuration of Atoms
The pairing of electron spins
1-8
Electron Configuration of Atoms
Table 1.3 The Ground-State Electron Configuration of Elements 1-18
• we show polarity by using the symbols d+ and d-, or by using an arrow with the arrowhead pointing toward the negative end and a plus sign on the tail of the arrow at the positive end
• each shell can hold 2n2 electrons (n = 1,2,3,4......)
N u mb er of Relative En ergies Electrons S hell of Electrons
S hell Can Hold in Thes e Shells
4
32
Lewis dot structure:
• the symbol of an element represents the nucleus and all inner shell electrons
• dots represent valence electrons
1-10
Lewis Dot Structures
The number of shared pairs
• one shared pair forms a single bond
• two shared pairs form a double bond
• three shared pairs form a triple bond
1-15
Polar and Nonpolar Covalent Bonds
1-9
Lewis Dot Structures
Gilbert N. Lewis Valence shell:
• the outermost occupied electron shell of an atom
Valence electrons:
• electrons in the valence shell of an atom; these electrons are used to form chemical bonds and in chemical reactions
• s (one per shell) • p (set of three per shell 2 and higher) • d (set of five per shell 3 and higher) .....
S hell O rb itals Contain ed in Th at S hell 3 3s , 3px, 3py, 3pz, p lu s five 3d orbitals 2 2s , 2px, 2py, 2pz 1 1s
N a+(1s22s22p6) + F-(1s22s22p6)
1-14
Covalent Bonds
The simplest covalent bond is that in H2
• the single electrons from each atom combine to form an electron pair
1-16
Polar and Nonpolar Covalent Bonds
• an example of a polar covalent bond is that of H-Cl
• the difference in electronegativity between Cl and H is 3.0 - 2.1 = 0.9
Table 1.4 Lewis Dot Structures for Elements 1-18
1A 2A 3A 4A 5A 6A 7A 8A
H.
He :
:: :: ::
.
..
.
.
Li . Be : B : C : .N : :O. : :F : :N e :
.
..
.
.
N a. M g : A l : Si : .P : :S. : :Cl : :A r :