Arrangement of Electrons in
Atoms
Electron Configurations
Review of Sections 1 & 2
1. What is the equation that related speed, wavelength,
and frequency?
2. Which theory of light, (wave or particle) best
explains the following phenomena?
a. The interference of light
b. The photoelectric effect
c. The emission of electromagnetic radiation by an
excited atom.
3. Compare and contrast the Bohr model and quantummechanical model of the atom.
4. What is the principal quantum number?
Review of Sections 1 & 2
5. How does “n” relate to the number of sublevels in
each energy level?
6. For n = 4, how many sublevels are there and what
are their designations?
7. How many possible orbital orientations are there for
d and f sublevels?
8. What is the relationship between n and the total
number of orbitals in each energy level?
9. How many electrons could be contained in the 3rd
energy level?
Electron Configurations
• Orbital Notation for Carbon

1s
 _ _ __
2s
2p
• Electron Configuration for carbon
1s22s22p2
“Orbital Filling” Rules
• Aufbau Principle
Electrons fill the lowest energy orbitals available
• Pauli Exclusion Principle
No two electrons in the same atom can have the
same set of four quantum numbers; orbitals can
hold a maximum of two electrons; two electrons in
one orbital must have opposite spins.
• Hund’s Rule
Electrons fill equal energy orbitals one at a time until
each is occupied by one electron; Electrons in
singly occupied orbitals have the same spin.
Write orbital diagrams and electron
configurations for each of the following atoms.
N
Se
F
Te
S
Ar
Cl
Ne