posted by Elda .
Which electron cannot occurr?
b) 1s^2 2s^2 2p^6 3s^2
c) 1s^2 1p^6 2s^2 2p^6
d) all can occurr
How do I figure this out?
s orbitals can contain 2 electrons maximum and p orbitals can contain 6. I do not see this condition being violated in any of the configurations you have listed. .
A is ok. B is ok. C is not ok since you may NOT have a 1p electron. Only s electrons may occur in the N = 1 level. I hope this helps.
DrBob is correct. No p orbitals are allowed in the n=1 "shell". n=2 can have s and p orbital electrons. n=3 can have s, p and d, etc. The different lower case letters that are used to designate orbitals were chosen for obscure reasons having to do with spectroscopy. As quantum mechanics began to explain the reasons for these rules, is became clear that the s, p, d, f etc orbitals have different integral multiples of h/(2 pi) for the electron angular momentum.