This outermost shell is known as the valence shell, and the electrons found in it are called valence electrons. In general, atoms are most stable, least reactive, when their outermost electron shell is full.

How do you find the outermost shell?

So we can use the column or group of an element to determine the number of electrons in its outermost shell, sometimes referred to as valence electrons. Elements from the fourth column of the periodic table, like carbon, have four electrons in their outermost electron shell or four valence electrons.

How many electrons are there in its outermost shell?

This is known as the octet rule, which states, with the exception of the innermost shell, that atoms are more stable energetically when they have eight electrons in their valence shell, the outermost electron shell.