Teacher Notes

Name Key Class Date

Orbital Diagrams & Electron Configuration

1. Compare and contrast Hund’s rule with the Pauli Exclusion Principle.

Both address the fact that orbitals can hold two electrons. The Pauli exclusion principle says that those two electrons must have opposite spins. Hund’s rule says that, within a sublevel, orbitals take one electron each before doubling up and those single electrons must have the same spin.

2. How does the figure to the right illustrate Hund’s rule?

One electron goes into each 2p orbital before placing a second electron in the first 2p orbital. The single electrons have the same spin.

3. How does the figure above illustrate the Pauli Exclusion Principle?

There are no more than two electrons in each orbital. When two electrons are present in an orbital, they have opposite spins.

4. Electron Configurations are written in the following form. Describe what each part represents.

energy level

total number of electrons in the energy sublevel

energy sublevel

5. State (yes/no) whether each of the following orbital diagrams conforms to the rules governing electron configuration. If not, explain what is wrong with the diagram. Note: only valence electrons are shown.

a. ↑↓ ↑↓ ↑ b. ↑↑ ↑ ↑ ↑ c. ↑↓ ↑ ↑ ↑2s 2p 2s 2p 2s 2p

a. No. Each of the three electrons in the 2p sublevel should be in a separate orbital with an up spin. (Hund’s rule)

b. No. The two electrons in the 2s orbital should have opposite spins. (Pauli exclusion principle)

c. Yes.

2p ↑↓ ↑ ↑

2s ↑↓

1s ↑↓

1s2

Teacher Notes

6. Identify the following atoms by their orbital diagrams and write the electron configuration

↑↓ ↑↓ ↑↓ ↑↓ ↑↓ ↑↓ ↑ ↑ ↑_____ _____ _____ _____ _____ _____ _____ _____ _____

1s 2s 2px 2py 2pz 3s 3px 3py 3pz

Atom: P Electron configuration: 1s 2 2s 2 2p 6 3s 2 3p 3

↑↓ ↑↓ ↑↓ ↑↓ ↑↓ ↑ _____ _____ _____ _____ _____ _____

1s 2s 2px 2py 2pz 3s

Atom: Na Electron configuration: 1s 2 2s 2 2p 6 3s 1

↑↓ ↑↓ ↑↓ ↑↓ ↑↓ ↑↓ ↑↓ ↑↓ ↑↓ ↑_____ _____ _____ _____ _____ _____ _____ _____ _____ _____

1s 2s 2px 2py 2pz 3s 3px 3py 3pz 4s

Atom: K Electron configuration: 1s 2 2s 2 2p 6 3s 2 3p 6 4s 1

7. Write orbital diagrams and electron configurations for the following atoms.

Symbol #e- Orbital diagram and electron configuration

N 7↑↓ ↑↓ ↑ ↑ ↑

_____ _____ _____ _____ _____ 1s22s22p3

1s 2s 2px 2py 2pz

O 8↑↓ ↑↓ ↑↓ ↑ ↑

_____ _____ _____ _____ _____ 1s22s22p4

1s 2s 2px 2py 2pz

Mn 25↑↓ ↑↓ ↑↓ ↑↓ ↑↓ ↑↓ ↑ ↑ ↑

_____ _____ _____ _____ _____ _____ _____ _____ _____1s 2s 2px 2py 2pz 3s 3px 3py 3pz

↑↓ ↑ ↑ ↑ ↑ ↑_____ _____ _____ _____ _____ _____ 1s22s22p63s23p64s23d5

4s 3dx2-y2 3dxy 3dyz 3dxz 3dz2

Ga 31↑↓ ↑↓ ↑↓ ↑↓ ↑↓ ↑↓ ↑ ↑ ↑

_____ _____ _____ _____ _____ _____ _____ _____ _____1s 2s 2px 2py 2pz 3s 3px 3py 3pz

↑↓ ↑↓ ↑↓ ↑↓ ↑↓ ↑↓ ↑_____ _____ _____ _____ _____ _____ _____ _____ _____

4s 3dx2-y2 3dxy 3dyz 3dxz 3dz2 4px 4py 4pz

1s22s22p63s23p64s23d104p1