Question

How many valence electrons are in an atom of magnesium?

Answer 1

Magnesium has two valence electrons.

Magnesium is element 12 and belongs to Group 2 of the Periodic Table. An element in Group 2 has two valence electrons.

Also, the electron configuration of Mg is 1s² 2s²2p⁶ 3s² or [Ne]3s². Since the 3s² electrons are the outermost electrons, magnesium has two valence electrons.

Answer 2

Magnesium has two valence electrons.

Explanation:

The electron configuration for magnesium is shown below.

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

The valence elctrons are the electrons in the third energy level (3s sublevel has two electrons in an atom of Mg)

Here is a video which discusses how to determine the electron configuration of magnesium.