For states with larger values of n that admit a d subshell, the d subshell is at even higher energy than the p subshell. In fact, its energy is higher than that of the s subshell for the n 1 state. With this in mind, 1. Which of the following are valid ground-state electron structures?
1. 1s2 2s2 2p63 s2 3p6 3d2
2. 1s2 2s2 2p6 3s2 3p6 3d11
3. 1s2 2s2 2p6 3s2 3p6 4s2 3d5
A. 1
B. 2
C. 3
D. 1 and 2
E. 1 and 3
F. 2 and 3
2. Which of the following is not a valid electron structure for an atom in its ground state? Use the fact that electrons fill the lowest energy states first and keep in mind the number of allowed states for each subshell.
A. 1s2 2s2 2p6 3s3
B. 1s2 2s2 2p6 3s2 3p4
C. 1s2 2s2 2p6 3s2
D. 1s2 2s2 2p6 3s2 3p5
E. 1s2 2s2 2p5