Valence electrons are those electrons that an atom uses in forming a bond with another atom. Generally, these electrons are found in the outermost shell of an element, regardless of whether any subshell of a lower shell is completely full.
Example:
Find the number of valence electrons for the following elements: potassium, krypton, silicon and carbon.
Potassium is located in group IA and therefore has 1 valence electron. Krypton is in the group labeled either '0' or 'VIII.' The outer shell of krypton contains the maximum number of electrons. Since a filled shell is more stable than a shell that is not filled, krypton does not tend to lose electrons. Likewise, since any additional electrons would
