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29 Atoms and Molecules
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Reading Quiz
Answer
1. What is the “Balmer formula” a formula for?
1. What is the “Balmer formula” a formula for?
A.
B.
C.
D.
Masses of atomic nuclei of hydrogen isotopes
Wavelengths in the hydrogen emission spectrum
Energies of stationary states of hydrogen
Probabilities of electron position in stationary states of
hydrogen
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A.
B.
C.
D.
Masses of atomic nuclei of hydrogen isotopes
Wavelengths in the hydrogen emission spectrum
Energies of stationary states of hydrogen
Probabilities of electron position in stationary states of
hydrogen
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1
Reading Quiz
Answer
2. Which of the following aspects of the stationary states of
hydrogen does Bohr’s analysis of the hydrogen atom get right?
2. Which of the following aspects of the stationary states of
hydrogen does Bohr’s analysis of the hydrogen atom get right?
A.
B.
C.
D.
The existence of a “spin” quantum number
The existence of a “magnetic” quantum number
The shapes of the electron clouds
The energies of the stationary states
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A.
B.
C.
D.
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Spectroscopy
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The existence of a “spin” quantum number
The existence of a “magnetic” quantum number
The shapes of the electron clouds
The energies of the stationary states
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Continuous Spectra and Blackbody Radiation
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Discrete Spectra of the Elements
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The Hydrogen Spectrum
Wavelengths of
visible lines in the
hydrogen spectrum
Balmer’s formula
l =
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91.1 nm
⎛ 1 1⎞
⎜ 2− 2⎟
⎝m n ⎠
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Rutherford’s Experiment
Using the Nuclear Model
Ionization
The nucleus
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Bohr’s Model of Atomic Quantization
Frequencies of Photons Emitted in Electron
Transitions
fphoton =
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Bohr’s Model of Atomic Quantization (cont’d)
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Isotopes
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Representing Atomic States
Energy-level diagram
ΔEatom
h
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The Bohr Hydrogen Atom
Energy-Level Diagram of the Hydrogen Atom
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The Quantum-Mechanical Hydrogen Atom
The Quantum-Mechanical Hydrogen Atom (cont’d)
1. Schrödinger found that the energy of the hydrogen atom is
given by the same expression found by Bohr, or
3. The plane of the electron’s orbit can be tilted, but only at
certain discrete angles. Each allowed angle is characterized
by a quantum number m, which must be one of the values
En = −
13.60 eV
n2
n = 1, 2,3,...
m = −l , −l + 1,...,0,..., l − 1, l
The integer n is called the principal quantum number.
2. The angular momentum L of the electron’s orbit must be one of
the values
L = l (l + 1) U
l = 0,1, 2,3,..., n − 1
The integer m is called the magnetic quantum number
because it becomes important when the atom is placed in a
magnetic field.
4. The electron’s spin can point only up or down. These two
orientations are described by the spin quantum number ms,
which must be one of the values
The integer l is called the orbital quantum number.
ms = −
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Energy and Angular Momentum of the Hydrogen
Atom
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1
1
or +
2
2
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Energy Levels in Multielectron Atoms
Hydrogen atom
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Multielectron atom
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Excited States and the Pauli Exclusion Principle
Helium atom
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Excitation by Absorption and Collision
Building Up the Periodic Table
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The Periodic Table
Lithium atom
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Emission Spectra
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Checking Understanding
Suppose that an atomic excited state decays to the ground state
by emission of two photons, with energies E1 and E2. Is it possible
for that excited state to decay to the ground state by emission of
a single photon with energy E1 + E2?
A. It is always possible, for every atom.
B. It is never possible, for any atom.
C It is
C.
i always
l
possible
ibl ffor h
hydrogen
d
atoms,
t
b
butt iis
unlikely for other atoms.
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Answer
Molecules
Suppose that an atomic excited state decays to the ground state
by emission of two photons, with energies E1 and E2. Is it possible
for that excited state to decay to the ground state by emission of
a single photon with energy E1 + E2?
A. It is always possible, for every atom.
B. It is never possible, for any atom.
C It is
C.
i always
l
possible
ibl for
f hydrogen
h d
atoms,
t
but
b t is
i
unlikely for other atoms.
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Fluorescence
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Checking Understanding
Which of the following is not a possible fluorescence process?
A.
B.
Absorption of red light and emission of green light
Absorption of ultraviolet light and emission of infrared
light
C. Absorption of ultraviolet light and emission of green light
D. Absorption of blue light and emission of red light
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Answer
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Stimulated Emission and Lasers
Which of the following is not a possible fluorescence process?
A. Absorption of red light and emission of green light
B. Absorption of ultraviolet light and emission of infrared
light
C. Absorption of ultraviolet light and emission of green light
D. Absorption of blue light and emission of red light
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Photon Amplification
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A Helium-Neon Laser
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