CHEM 35

General Chemistry

Quiz #6

November 3, 2000

Name:       Solution Key

1. If the electron in a hydrogen atom undergoes a transition from n=4 to n=1, is energy absorbed or emitted? Briefly explain.

Since the ENERGY of the orbital increases with increasing n,

E_n=4 > E_n=1 and so a transition from the HIGHER energy leverl to the LOWER energy level will result in the EMISSION of energy from the atom (in the form of a photon).

2. Name the subshell corresponding to the following set of quantum numbers: n=4, l=3, m_l=2.

The subshell is determined by the value of the azimuthal QN (l):

l = 0, s-orbitals

l = 1, p-orbitals

l = 2, d-orbitals

l = 3, f-orbitals

So, the subshell is the set of seven 4f-orbitals (the m_l value specifies a particular orbital in the subshell).

3. Vanadium is a transition metal (Z=23). What is its ground state electron configuration?

23 electrons get filled like this:

1s²2s²2p⁶3s²3p⁶4s²3d³

OR: [Ar]4s²3d³

Remember: fill the 4s before the 3d (groups 1A and 2A before the transition metals)

4. Carbon’s ground state has two electrons in the 2p-orbitals. Are their spins paired or unpaired? Explain.

There are three p-orbitals; Hund’s Rule says that the lowest energy configuration will result when electrons are placed first into separate orbitals and have the same spin. So, the two electrons will be unpaired (each in a different orbital).