© 2010 Pearson Education, Inc. Slide 29-2

29 Atoms and Molecules

© 2010 Pearson Education, Inc.

© 2010 Pearson Education, Inc.

© 2010 Pearson Education, Inc. Slide 29-3

© 2010 Pearson Education, Inc. Slide 29-4

© 2010 Pearson Education, Inc. Slide 29-5

© 2010 Pearson Education, Inc.

Spectroscopy

Slide 29-10

© 2010 Pearson Education, Inc.

Continuous Spectra and Blackbody Radiation

Slide 29-11

© 2010 Pearson Education, Inc.

Discrete Spectra of the Elements

Slide 29-12

© 2010 Pearson Education, Inc.

The Hydrogen Spectrum

Balmer’s formula

Wavelengths of visible lines in the hydrogen spectrum

Slide 29-13

© 2010 Pearson Education, Inc.

Rutherford’s Experiment

Slide 29-14

© 2010 Pearson Education, Inc.

Using the Nuclear ModelIonization

The nucleus Isotopes

Slide 29-15

© 2010 Pearson Education, Inc.

Bohr’s Model of Atomic Quantization

Slide 29-16

© 2010 Pearson Education, Inc.

Bohr’s Model of Atomic Quantization (cont’d)

Slide 29-17

© 2010 Pearson Education, Inc.

Frequencies of Photons Emitted in Electron Transitions

Slide 29-18

© 2010 Pearson Education, Inc.

Representing Atomic StatesEnergy-level diagram

Slide 29-19

© 2010 Pearson Education, Inc.

The Bohr Hydrogen Atom

Slide 29-20

© 2010 Pearson Education, Inc.

Energy-Level Diagram of the Hydrogen Atom

Slide 29-21

© 2010 Pearson Education, Inc.

1. 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.

2. The angular momentum L of the electron’s orbit must be one of the values

The integer l is called the orbital quantum number.

The Quantum-Mechanical Hydrogen Atom

Slide 29-22

© 2010 Pearson Education, Inc.

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

The integer m is called the magnetic quantum number because it becomes important when the atom is placed in a magnetic field.

3. 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 Quantum-Mechanical Hydrogen Atom

Slide 29-23

© 2010 Pearson Education, Inc.

Energy Levels in Multielectron AtomsHydrogen atom Multielectron atom

Slide 29-25

© 2010 Pearson Education, Inc.

Excited States and the Pauli Exclusion PrincipleHelium atom Lithium atom

Slide 29-26

© 2010 Pearson Education, Inc.

The Periodic Table

Slide 29-27

© 2010 Pearson Education, Inc.

Building Up the Periodic Table

Slide 29-28

© 2010 Pearson Education, Inc.

Excitation by Absorption and Collision

Slide 29-29

© 2010 Pearson Education, Inc.

Emission Spectra

Slide 29-30

© 2010 Pearson Education, Inc.

Molecules

Slide 29-33

© 2010 Pearson Education, Inc.

Fluorescence

Slide 29-34

© 2010 Pearson Education, Inc.

Stimulated Emission and Lasers

Slide 29-37

© 2010 Pearson Education, Inc.

Photon Amplification

Slide 29-38

© 2010 Pearson Education, Inc.

A Helium-Neon Laser

Slide 29-39

© 2010 Pearson Education, Inc.

Reading Quiz1. What is the “Balmer formula” a formula for?

A. Masses of atomic nuclei of hydrogen isotopes

B. Wavelengths in the hydrogen emission spectrum

C. Energies of stationary states of hydrogen

D. Probabilities of electron position in stationary states of hydrogen

Slide 29-6

© 2010 Pearson Education, Inc.

Answer 1. What is the “Balmer formula” a formula for?

A. Masses of atomic nuclei of hydrogen isotopes

B. Wavelengths in the hydrogen emission spectrum

C. Energies of stationary states of hydrogen

D. Probabilities of electron position in stationary states of hydrogen

Slide 29-7

© 2010 Pearson Education, Inc.

Reading Quiz2. Which of the following aspects of the stationary states of

hydrogen does Bohr’s analysis of the hydrogen atom get right?

A. The existence of a “spin” quantum number

B. The existence of a “magnetic” quantum number

C. The shapes of the electron clouds

D. The energies of the stationary states

Slide 29-8

© 2010 Pearson Education, Inc.

Answer 2. Which of the following aspects of the stationary states of

hydrogen does Bohr’s analysis of the hydrogen atom get right?

A. The existence of a “spin” quantum number

B. The existence of a “magnetic” quantum number

C. The shapes of the electron clouds

D. The energies of the stationary states

Slide 29-9

© 2010 Pearson Education, Inc.

Checking UnderstandingSuppose 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 always possible for hydrogen atoms, but is unlikely for other atoms.

Slide 29-31

© 2010 Pearson Education, Inc.

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?

A. It is always possible, for every atom.

B. It is never possible, for any atom.

C. It is always possible for hydrogen atoms, but is unlikely for other atoms.

Slide 29-32

© 2010 Pearson Education, Inc.

Checking UnderstandingWhich 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

Slide 29-35

© 2010 Pearson Education, Inc.

Answer 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

Slide 29-36