# What is the electron configuration of copper?

Copper is in the ninth column of the transition metals in the d block of the fourth energy level of the periodic table. This would make the electron configuration for copper, $1 {s}^{2} 2 {s}^{2} 2 {p}^{6} 3 {s}^{2} 3 {p}^{6} 4 {s}^{2} 3 {d}^{9}$ or in noble gas configuration [Ar] $4 {s}^{2} 3 {d}^{9}$.
[Ar] $4 {s}^{1} 3 {d}^{10}$.