Terms Allowed in Spectroscopic Structure of Calcium

[jeffbarrington]

Homework Statement

Why can't we have 4s^2 3S1 calcium? I've looked up a table of terms and this is never given, so I guess we can't have it. Why can't the spins of each of the outer electrons add to give S = 1, J = 1, and a degeneracy of 3? I guess the answer must be pretty basic since nobody has asked about this that I can find, so what's going on?

Homework Equations

The Attempt at a Solution

 

[Charles Link]

I think this one is simple: Two electrons in the same orbital implies S=0 because the spins must be opposite.

 

[jeffbarrington]

I think this one is simple: Two electrons in the same orbital implies S=0 because the spins must be opposite.

Oh yeah, completely forgot about the PEP! Thanks for taking your time to answer my dumb question!