# What is the electron configuration of calcium?

$C a : \left[A r\right] 4 {s}^{2}$
Calcium has an atomic number of 20. Simply use this information to obtain its electronic configuration. Thus, $C a : 1 {s}^{2} 2 {s}^{2} 2 {p}^{6} 3 {s}^{2} 3 {p}^{6} 4 {s}^{2}$ or simply $C a : \left[A r\right] 4 {s}^{2}$.