# Which ion with a charge of -2 has an electron conﬁguration of 1s^2 2s^2 2p^6?

Nov 14, 2015

If there are 10 electrons in total and a formal negative charge of $- 2$, there must be 8 positive charges in the nucleus.

#### Explanation:

Since $Z$ $=$ $8$. the identity of this nucleus must be oxygen. Note that you will never sit a Chemistry or Physics exam without access to a Periodic Table. You must have this, and if you don't raise merry hell.