# What is the electron configuration of Ca+2?

Nov 2, 2015

The electron configuration of a $\text{Ca"^(2+)}$ ion is $\text{1s"^2"2s"^2"2p"^6"3s"^2"3p"^6}$.

#### Explanation:

The atomic number of calcium is 20. This means that in a neutral calcium atom, there are 20 protons in its nucleus. A neutral calcium atom also has 20 electrons. The electron configuration of a neutral calcium atom is $\text{1s"^2"2s"^2"2p"^6"3s"^2"3p"^6"4s"^2}$.

A calcium $2 +$ ion has lost its two valence electrons, and now has $18$ electrons. The electron configuration of a $\text{Ca"^(2+)}$ ion is $\text{1s"^2"2s"^2"2p"^6"3s"^2"3p"^6}$, which is isoelectronic with the noble gas argon.