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Chapter 6

CHE 101 Chapter Notes - Chapter 6: Bohr Model, Lucretius, Wave Function


Department
Chemistry
Course Code
CHE 101
Professor
Atwood Jim
Chapter
6

Page:
of 6
Chapter Six
Electron Structures of Atoms Review Sheet
Atoms and Atomic Theory
Postulates:
I. For awhile, it was thought that there were only four elements: earth, wind, fire, and water
a. This was postulated in the 5th century BCE by the Greeks, and lasted for 2,000
years
II. Lucretius hypothesized that sour atoms have barbs, while bland atoms are smooth
A. Obviously, this was incorrect
III. Dalton’s Atomic Theory
A. Atoms of different elements are different and not changed into each other by
chemical reactions (technically, this can be done nuclearly)
1. He did not state how these atoms were different
2. This disproved Alchemy (a field that sought to convert lead to gold)
IV. Discovery of Electrons
A. Mass = 9.11 x10^-28 g
B. Charge = 1.6 x10^-19 coul
V. Rutherford Gold Foil
A. Discovered that all weight (mass) is in the nucleus of an atom
B. Bombarded a thin gold foil with alpha particles
1. Most of these particles passed through, but some bounced back
a) He described this as being “like shooting a cannon at tissue paper
and having it come back at you
2. This led him to conclude that all of the mass of an atom is located in the
nucleus
VI. Spectrocity
A. Line spectra are different for each element
B. See lecture notes for more information
VII. Bohr Atom
A. A planetary model
VIII. de Broglie
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Chapter Six
Electron Structures of Atoms Review Sheet
A. Wave nature of an electron
B. Reasoned that if light can have wave characteristics, why can’t electrons?
C.  
D.   
1. h = Planck’s Constant
2. M = mass
3. V = velocity
IX. Heisenberg Uncertainty Principle
A. Postulates that you cannot know both the position and energy at the same time
B.   
C. = position; = energy
Wave Mechanics
I. Schrodinger Equation
A. Allows one to solve for the energy of an electron
II. The Bohr theory gave energy and radius
III. Quantum mechanics (the solution to Schrodinger’s Equation) gives wavefunctions - n, l,
mL
A. This describes all electrons in an atom
IV. Since an electron cannot be precisely located, one must be satisfied with probability
which is proportional to (
A. Electron-density distributions
1. Dots represent probability
2. How do we define the size of atoms?
a) There will always be uncertainty
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Chapter Six
Electron Structures of Atoms Review Sheet
Orbitals
I. The wave functions are called orbitals and have corresponding energies.
II. Each wave function is described by three quantum numbers - N, L, mL
A. N
1. The principle quantum number
2. May only be an integer value greater than or equal to one (n = 1,2,3…)
3. Larger values of n means that the electron spends more time away from
the nucleus
B. L
1. The azimuthal quantum number
2. Defines the shape of the orbital
3. The possible values of L depend on n
a) L = 0,1,2…(n-1)
b) If n was 3, L could only be 0,1, or 2.
C. ML
1. The magnetic quantum number
2. Describes the orientation in space
3. Possible values depend on L
a) ML = -L, (-L+1)...0…, L-1, L
III. Orbital Naming
A. S Orbital
1. L = 0
2. mL = 0
3. One orbital
B. P Orbital
1. L = 1
2. mL = -1, 0, 1
3. Three orbitals
C. D Orbital
1. L = 2
2. mL = -2, -1, 0, 1, 2
3. Five orbitals
D. F Orbital
1. L = 3
2. mL = -3, -2, -1, 0, 1, 2
3. Seven orbitals
IV. The principal quantum number gives us the distance from the nucleus
V. Where there is zero probability of an electron existing, a node exists
Electron Spin
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