Baby-Quiz 1.If all objects emit radiation, why don’t we see most of them in the dark? 2.Suppose you were a nineteenth-century scientist who had just discovered.

Baby-Quiz1. If all objects emit radiation, why don’t we see most of them in the

dark?

2. Suppose you were a nineteenth-century scientist who had just discovered a new phenomenon known as Zeta rays. What experiment could you perform to define if Zeta rays are charged particles or e/m waves? Could this experiment distinguish between neutral particles and an e/m wave?

3. If a metal surface is illuminated by light at a single frequency, why don’t all the photoelectrons have the same kinetic energy when they leave the metal’s surface?

4. What property of the emitted electrons depends on the intensity of incident light?What property of the emitted photoelectrons depends on the frequency of incident light?

1. What meaning do we give to the square of the matter-wave amplitude?

2. An electron and proton have the same speeds. Which has the longer wavelength? Why?

3. The wavelength of red light is 600 nm. An electron with a speed of 1.2 km/s has the same wavelength. Will the electron look red? Explain.

Particle in a Box

Where would you most likely find an electron in the first excited state for a one-dimensional box?

Quantum Mechanical View of Atoms

The electron can be thought of as spread out in space as a “cloud”.

Quantum Mechanics of the Hydrogen Atom

n – principal quantum number, positive integer;

l – orbital quantum number, is related to the magnitude of the angular momentum of the electron; at given n can take integer values from 0 to (n-1);

ml – magnetic quantum number, is related to the direction of the electron’s angular momentum, and it can take an integer values from –l to +l.

Zeeman Effect

Spin Quantum Number, ms

Conceptual Example: Possible States for n=3

How many different states are possible for an electron whose principal quantum number is n=3?

Selection Rule

Another prediction of quantum mechanics is that when a photon is emitted or absorbed, transitions can occur only between states with values of l that differ by one unit.

The Exclusion Principle

No two electrons in an atom can occupy the same quantum state.

Complex Atoms and Periodic Table of Elements

1. How many electrons have the quantum numbers n=5 and l=1?

2. How many electrons can have the quantum numbers n=5 and l=4?

3. Why do some minerals glow when they are illuminated with ultraviolet light?