How many core electrons are in a ground state atom of arsenic?

Question

Quizplus · Accepted Answer

The atomic number of arsenic is 33, meaning it has 33 electrons total. The ground state electron configuration of arsenic is 1s22s22p63s23p63d104s24p3. The core electrons are those in the innermost energy levels, so we count all electrons except for those in the outermost energy level. In this case, there are 2 electrons in the 1s energy level, 2 in the 2s, and 6 in the 2p, for a total of 10 core electrons.

How Many Core Electrons Are in a Ground State Atom