Question

What is the electron configuration of the `"As"^(3-)"` ion?

Answer 1

The electron configuration for the `"As"^(3-)"` ion is `["Ar"]"3d"^10"4s"^2"4p"^6"`.

Explanation:

Arsenic, As, has atomic number 33, which is the number of protons in the nuclei of its atoms. A neutral As atom would also have 33 electrons. The electron configuration of a neutral arsenic atom is `["Ar"]"3d"^10"4s"^2"4p"^3"`.

An arsenic 3- ion `("As"^(3-)")`, has gained three electrons, and its electron configuration is `["Ar"]"3d"^10"4s"^2"4p"^6"`, which is isoelectronic with the noble gas krypton, Kr.