For the element with the electron configuration
1s22s22p63s2, one of the 3s electrons will be shielded
from the nuclear charge most effectively by a...
(A) 1s electron (B) 2s electron
(C) 2p electron (D) 3s electron
The answer is supposed to be A. I guessed C (not really sure why), could someone explain? Thanks.
Btw, this was one of the problems I got wrong on the national chem olympiad exam (didn't make it into the study camp, but at least I got honorable mention). Oh well, there's next year to try again.