Why are valence electrons important in chemical bonding?
The number of valence electrons an atom has will determine the what type and how many chemical bonds the atom will form.
Delocalized valence electrons produce metallic bonds (bonds between atoms of metals) which give metals unique properties such as conductivity and ductility (draw metal into wires).
Valence electrons are the electrons that are shared between atoms which are covalently bonded to each other.
Valence electrons are the electrons which are transferred when ionic bonds are formed.
Here is a video reviewing how you can figure out how many valence electrons an atom has.