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Spectroscopy
29 Atoms and Molecules
Spectroscopy
Atoms
Bohr
Hydrogen
Excited States
Lasers
Slide 29-2
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Continuous Spectra and Blackbody Radiation
Slide 29-11
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The Hydrogen Spectrum
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Slide 29-10
Discrete Spectra of the Elements
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Slide 29-12
Rutherford’s Experiment
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 
Slide 29-13
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Using the Nuclear Model
Bohr’s Model of Atomic Quantization
Ionization
The nucleus
Isotopes
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Slide 29-15
Bohr’s Model of Atomic Quantization (cont’d)
Slide 29-16
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Frequencies of Photons Emitted in Electron
Transitions
fphoton =
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Slide 29-17
Representing Atomic States
∆Eatom
h
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Slide 29-18
The Bohr Hydrogen Atom
Energy-level diagram
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Slide 29-19
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2
Energy-Level Diagram of the Hydrogen Atom
The Quantum-Mechanical Hydrogen Atom
1. Schrödinger found that the energy of the hydrogen atom is
given by the same expression found by Bohr, or
En = −
13.60 eV
n2
n = 1, 2,3,...
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 l is called the orbital quantum number.
Slide 29-21
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The Quantum-Mechanical Hydrogen Atom (cont’d)
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
Slide 29-22
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Energy and Angular Momentum of the Hydrogen
Atom
m = −l , −l + 1,..., 0,..., l − 1, l
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
ms = −
1
1
or +
2
2
Slide 29-23
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Excited States and the Pauli Exclusion Principle
Energy Levels in Multielectron Atoms
Hydrogen atom
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Slide 29-24
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Multielectron atom
Helium atom
Slide 29-25
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Lithium atom
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3
The Periodic Table
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Building Up the Periodic Table
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Molecules
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Emission Spectra
Excitation by Absorption and Collision
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Slide 29-30
Fluorescence
Slide 29-33
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4
Photon Amplification
Stimulated Emission and Lasers
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A Helium-Neon Laser
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