Determine the identity of the element that contains exactly three 4p electrons in the ground state

Answer: Arsenic

Explanation: The element that contains exactly three 4p electrons at ground state is

Arsenic, a group 15 and period 4 solid (20°C) element with

atomic weight 74.9216g/mol whose Electronic configuration is

1s²2s²2p⁶3s²3p⁶3d¹⁰4s²4p³ with the condensed electronic configuration as [Ar] 3d¹⁰ 4s² 4p³.

Arsenic (As)

Explanation:

The electron configuration of arsenic is; 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p3 or [Ar]4s2 3d10 4p3 for short.

Arsenic is a group 15 element. All group 15 elements have outermost electron configuration of ns^2 np^3. Arsenic is the only member of the group that possesses exactly three electrons in the 4p orbital.

Hence As is the element we need to identity in the question.