29 Atoms and Molecules Slide 29-2

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Spectroscopy Slide 29-10

Continuous Spectra and Blackbody Radiation Slide 29-11

Discrete Spectra of the Elements Slide 29-12

The Hydrogen Spectrum Wavelengths of visible lines in the hydrogen spectrum Balmer’s formula Slide 29-13

Rutherford’s Experiment Slide 29-14

Using the Nuclear Model Ionization The nucleus Isotopes Slide 29-15

Bohr’s Model of Atomic Quantization Slide 29-16

Bohr’s Model of Atomic Quantization (cont’d) Slide 29-17

Frequencies of Photons Emitted in Electron Transitions Slide 29-18

Representing Atomic States Energy-level diagram Slide 29-19

The Bohr Hydrogen Atom Slide 29-20

Energy-Level Diagram of the Hydrogen Atom Slide 29-21

The Quantum-Mechanical Hydrogen Atom Schrödinger found that the energy of the hydrogen atom is given by the same expression found by Bohr, or The integer n is called the principal quantum number. The angular momentum L of the electron’s orbit must be one of the values The integer l is called the orbital quantum number. Slide 29-22

The Quantum-Mechanical Hydrogen Atom 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 The integer m is called the magnetic quantum number because it becomes important when the atom is placed in a magnetic field. 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 Slide 29-23

Energy Levels in Multielectron Atoms Hydrogen atom Multielectron atom Slide 29-25

Excited States and the Pauli Exclusion Principle Helium atom Lithium atom Slide 29-26

The Periodic Table Slide 29-27

Building Up the Periodic Table Slide 29-28

Excitation by Absorption and Collision Slide 29-29

Emission Spectra Slide 29-30

Molecules Slide 29-33

Fluorescence Slide 29-34

Stimulated Emission and Lasers Slide 29-37

Photon Amplification Slide 29-38

A Helium-Neon Laser Slide 29-39

Reading Quiz What is the “Balmer formula” a formula for? 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 Answer: B Slide 29-6

Answer What is the “Balmer formula” a formula for? 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 Answer: B Slide 29-7

Reading Quiz Which of the following aspects of the stationary states of hydrogen does Bohr’s analysis of the hydrogen atom get right? 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 Answer: D Slide 29-8

Answer Which of the following aspects of the stationary states of hydrogen does Bohr’s analysis of the hydrogen atom get right? 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 Answer: D Slide 29-9

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? It is always possible, for every atom. It is never possible, for any atom. It is always possible for hydrogen atoms, but is unlikely for other atoms. Answer: C Slide 29-31

Answer 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? It is always possible, for every atom. It is never possible, for any atom. It is always possible for hydrogen atoms, but is unlikely for other atoms. Answer: C Slide 29-32

Checking Understanding Which of the following is not a possible fluorescence process? Absorption of red light and emission of green light Absorption of ultraviolet light and emission of infrared light Absorption of ultraviolet light and emission of green light Absorption of blue light and emission of red light Answer: A Slide 29-35

Answer Which of the following is not a possible fluorescence process? Absorption of red light and emission of green light Absorption of ultraviolet light and emission of infrared light Absorption of ultraviolet light and emission of green light Absorption of blue light and emission of red light Answer: A Slide 29-36