# Number of protons in a 5g orbital

1. Dec 5, 2009

### Razael

1. The problem statement, all variables and given/known data

Using a strict interpretation of the n+l rule, how many protons would an atom need to create a ground state electron configuration with one electron in a 5g orbital? Give electron configuration.

2. Relevant equations

3. The attempt at a solution

g is an l value of 4, 4+5 = 9. So 5g is filled after other orbitals with n+l's lower than 9, or equal but with higher n values.

This puts 5g after 9s, does it not? I have no clue what to do from here.

2. Dec 5, 2009

### Staff: Mentor

Atom is neutral - that means charge of electrons and charge of nucleus cancel out, they are identical (just one is positive, other negative).

3. Dec 5, 2009

### Razael

The answer (which is given) is 121 protons. Since the atom is neutral, there'd also be 121 electron, so I'd look for an electron configuration where all orbitals before 5g + 1 = 121.

I don't know what 5g comes after though.

4. Dec 5, 2009

5. Dec 5, 2009

### Razael

Okay, added up all electrons up to and including 8s and got 120. Adding one for 5g gives me 121.

I still don't understand why it has to be preceded by 8s though. Why not, say, 6d?

6. Dec 5, 2009