Problem- Which of these electron configurations are for atoms in the ground state? In excited states? Which are impossible?
1) 1s2 2s1
2) 1s2 2s2 2p3
3) [Ne] 3s2 3p3 4s1
4) [Ne] 3s2 3p6 4s3 3d2
5) [Ne] 3s2 3p6 4f4
6) 1s2 2s2 2p4 3s2
Here is the problem which I am struggling on, please help me