Question

<!--td {border: 1px solid #ccc;}br {mso-data-placement:same-cell;}--> What are valence electrons? How many valence electrons does a magnesium atom have?

Answer 1

<!--td {border: 1px solid #ccc;}br {mso-data-placement:same-cell;}--> The electrons present in the outermost shell of an atom​ are called valence electrons. These electrons play a major role in chemical reactions by deciding the combining capacity of an element​ called valency.
The electronic configuration of the magnesium atom can be written as 2, 8, 2. Looking at the configuration, we can say that magnesium has two valence electrons.