What about this do you not understand. By the way, leave space like this.
1s2 2s2 2p6 3s2 otherwise it makes no sense.
How many of the following electron configurations are allowed?
1s22s22p7 1s22s22p62d1 [Ne]4s24p4 [Ar]3d64s2 1s22s22p83s23p4
1 answer