How many valence electrons does calcium have?

Calcium has 2 .

Calcium has 20 electrons so they are arranged 2. 8. 8. 2

Using orbital notation the electron structure is:

##1s^(2)2s^(2)2p^(6)3s^(2)3p^(6)4s^(2)##

You can see that there are 2 electrons in the outer energy level and these are the .