Question

What is the electron configuration of an element with atomic number 19?

Answer 1

`1s^2 2s^2 2p^6 3s^2 3p^6 4s^1`

Explanation:

This is the electron configuration of Potassium K # 19
There are 2 electrons in the first shell
There are 8 electrons in the second shell
There are 8 electrons in the third shell
leaving only 1 electron in the fourth and valence shell.

This results in ionized potassium almost always having a charge of `K^(+)`:

`K -> K^(+) + e^(-)`