Chapter 17 – Properties of Atoms and the Periodic Table17章–原子的属性与元素周期表
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Makes up about 99% of the atomic mass
A. Protons – Positive charge (1) The number of protons determines what the element is.
(2) Proton numbers never change.
through a gas – Gas gave off rays that were made of negatively charged particles Corpuscles Today – Electrons
Thomson’s Model
2. Atoms thought to have a neutral charge – Finding electrons changed idea.
Atoms – Nucleus
Neutrons – Neutral charge (1) Neutron numbers can change.
Isotopes – Atoms of the same element that have the same number of protons but different numbers of neutrons.
substance are alike.源自Pure Substance
Element – A substance that cannot be broken down into simpler substances by ordinary means (heating or any chemical process).
A. Thomson unable to show particles that had a positive charge.
3. Proposed a model of an atom – Plum Pudding
Plum Pudding
The atom was made of a pudding-like positively charged material throughout which negatively charged electrons were scattered, like plums in a pudding.
sheets as if they had hit something solid – Some bounced straight back.
Conclusion: Atom must have a small, dense, positively charged center – Nucleus
Rutherford’s Model
definite orbits around the nucleus. B. The orbits, or energy levels, are located at
certain distances from the nucleus.
4. Worked in explaining the structure and behavior of simple atoms – Not complex atoms
A. Concluded that matter could not be divided into smaller and smaller pieces forever.
B. Named the smallest pieces of matter – Atom.
The atom
The Greek Model Democritus 2. Hypothesized – Atoms were infinite in number,
Atoms – Nucleus
Neutrons – Neutral charge
(2) Mass Number – The sum of the protons and neutrons found in nucleus of an atom.
(a) Determining the number of neutrons – Subtract the Atomic Number from the Mass Number (round the number)
Rutherford’s Model
Ernest Rutherford – English physicist.
1. Rutherford’s Experiment – A. Firing a stream of tiny positively charged
particles at thin sheet of gold foil.
are indivisible and indestructible particles. – Similar to Democritus B. Atoms of the same element are exactly alike.
Dalton’s Model
Basic Ideas of Dalton’s Atomic Theory (con’t) : C. Atoms of different elements are different. D. Compounds are formed by the joining of atoms of
Basic building blocks of matter
Dalton’s Model
John Dalton – English chemist
Basic Ideas of Dalton’s Atomic Theory : A. All elements are composed of atoms – Atoms
Rutherford’s Model
2. Rutherford’s Theory
C. Between the nucleus and the electrons was mostly empty space.
D. Negatively charged electrons were held in an atom by the attraction between them and the positively charged nucleus.
2. Rutherford’s Theory Two parts of an atom: A. All of an atom’s positively charged particles
were contained in the nucleus.
B. The negatively charged electrons were scattered outside the nucleus around the atom’s edge.
QUESTION
What are the significant differences between Rutherford’s model and the Bohr model of the atom?
The orbits of the electrons are not random but are fixed distances from the nucleus. Protons and neutrons are in the nucleus
electrons orbit the nucleus.
Bohr Model
Niels Bohr – Danish scientist.
1. Proposed the location of electrons.
Bohr Model
2. Bohr’s Theory – A. Electrons move in
90 naturally occurring elements. Arranged in an order on Periodic Table
The atom
The Greek Model
1. Democritus – Greek philosopher who theorized about whether matter could be divided into smaller and smaller pieces.
QUESTION
What are the significant differences between Thomson’s model and Rutherford’s model of the atom?
The mass of the atom is at the center of the atom instead of throughout the atom
Atoms & the Periodic Table
Matter
Anything that has mass and volume (takes up space)
Pure Substance A type of matter with a fixed composition. All of particles that make up this
Atoms – Nucleus
(3) Atomic Mass Unit (amu) – Unit used to measure the relative masses of subatomic particles; A proton has a mass of 1 amu.
(4) Atomic Number – Indicates the number of protons found in the nucleus of an atom.
always moving, and capable of joining together.
3. Not widely accepted – Could not prove theories.
The atom
Atom – The smallest particle of an element that has the properties of that element.
Rutherford’s Model
1. Rutherford’s Experiment – B. Most of the positively charged “bullets” passed
through the gold atoms in the sheet of foil. C. Some “bullets” did bounce away from the gold
B. Atom has a small positively charged nucleus surrounded by a large region in which there are enough electrons to make the atom neutral.
Atom – Nucleus
Electron Cloud Model
Modern atomic model
A. Electrons do not move about an atom in a definite path
Can only predict where an electron is most likely to be found.
2 or more elements.
Foundation of modern chemistry
Thomson’s Model
J.J. Thomson – English chemist
1. Basic Idea of Thomson’s Model A. Atoms are made of even smaller particles. B. Studied the passage of an electric current
QUESTION
What are the significant differences between Dalton’s model and Thomson’s model of the atom?
Atom was not a single particle It was made of positive and negative particles
A. Protons – Positive charge (1) The number of protons determines what the element is.
(2) Proton numbers never change.
through a gas – Gas gave off rays that were made of negatively charged particles Corpuscles Today – Electrons
Thomson’s Model
2. Atoms thought to have a neutral charge – Finding electrons changed idea.
Atoms – Nucleus
Neutrons – Neutral charge (1) Neutron numbers can change.
Isotopes – Atoms of the same element that have the same number of protons but different numbers of neutrons.
substance are alike.源自Pure Substance
Element – A substance that cannot be broken down into simpler substances by ordinary means (heating or any chemical process).
A. Thomson unable to show particles that had a positive charge.
3. Proposed a model of an atom – Plum Pudding
Plum Pudding
The atom was made of a pudding-like positively charged material throughout which negatively charged electrons were scattered, like plums in a pudding.
sheets as if they had hit something solid – Some bounced straight back.
Conclusion: Atom must have a small, dense, positively charged center – Nucleus
Rutherford’s Model
definite orbits around the nucleus. B. The orbits, or energy levels, are located at
certain distances from the nucleus.
4. Worked in explaining the structure and behavior of simple atoms – Not complex atoms
A. Concluded that matter could not be divided into smaller and smaller pieces forever.
B. Named the smallest pieces of matter – Atom.
The atom
The Greek Model Democritus 2. Hypothesized – Atoms were infinite in number,
Atoms – Nucleus
Neutrons – Neutral charge
(2) Mass Number – The sum of the protons and neutrons found in nucleus of an atom.
(a) Determining the number of neutrons – Subtract the Atomic Number from the Mass Number (round the number)
Rutherford’s Model
Ernest Rutherford – English physicist.
1. Rutherford’s Experiment – A. Firing a stream of tiny positively charged
particles at thin sheet of gold foil.
are indivisible and indestructible particles. – Similar to Democritus B. Atoms of the same element are exactly alike.
Dalton’s Model
Basic Ideas of Dalton’s Atomic Theory (con’t) : C. Atoms of different elements are different. D. Compounds are formed by the joining of atoms of
Basic building blocks of matter
Dalton’s Model
John Dalton – English chemist
Basic Ideas of Dalton’s Atomic Theory : A. All elements are composed of atoms – Atoms
Rutherford’s Model
2. Rutherford’s Theory
C. Between the nucleus and the electrons was mostly empty space.
D. Negatively charged electrons were held in an atom by the attraction between them and the positively charged nucleus.
2. Rutherford’s Theory Two parts of an atom: A. All of an atom’s positively charged particles
were contained in the nucleus.
B. The negatively charged electrons were scattered outside the nucleus around the atom’s edge.
QUESTION
What are the significant differences between Rutherford’s model and the Bohr model of the atom?
The orbits of the electrons are not random but are fixed distances from the nucleus. Protons and neutrons are in the nucleus
electrons orbit the nucleus.
Bohr Model
Niels Bohr – Danish scientist.
1. Proposed the location of electrons.
Bohr Model
2. Bohr’s Theory – A. Electrons move in
90 naturally occurring elements. Arranged in an order on Periodic Table
The atom
The Greek Model
1. Democritus – Greek philosopher who theorized about whether matter could be divided into smaller and smaller pieces.
QUESTION
What are the significant differences between Thomson’s model and Rutherford’s model of the atom?
The mass of the atom is at the center of the atom instead of throughout the atom
Atoms & the Periodic Table
Matter
Anything that has mass and volume (takes up space)
Pure Substance A type of matter with a fixed composition. All of particles that make up this
Atoms – Nucleus
(3) Atomic Mass Unit (amu) – Unit used to measure the relative masses of subatomic particles; A proton has a mass of 1 amu.
(4) Atomic Number – Indicates the number of protons found in the nucleus of an atom.
always moving, and capable of joining together.
3. Not widely accepted – Could not prove theories.
The atom
Atom – The smallest particle of an element that has the properties of that element.
Rutherford’s Model
1. Rutherford’s Experiment – B. Most of the positively charged “bullets” passed
through the gold atoms in the sheet of foil. C. Some “bullets” did bounce away from the gold
B. Atom has a small positively charged nucleus surrounded by a large region in which there are enough electrons to make the atom neutral.
Atom – Nucleus
Electron Cloud Model
Modern atomic model
A. Electrons do not move about an atom in a definite path
Can only predict where an electron is most likely to be found.
2 or more elements.
Foundation of modern chemistry
Thomson’s Model
J.J. Thomson – English chemist
1. Basic Idea of Thomson’s Model A. Atoms are made of even smaller particles. B. Studied the passage of an electric current
QUESTION
What are the significant differences between Dalton’s model and Thomson’s model of the atom?
Atom was not a single particle It was made of positive and negative particles