Valence Electrons
Valence electrons are defined as electrons that are found in the outermost energy
levels of an atom. The number of valence electrons in any atom of a
Representative Element corresponds to its Group Number. All elements within a
Group or Family, have the same number of electrons in their outermost energy
levels. This outermost energy level is referred to as an element's valence
shell, as sketched below.
The maximum number of electrons that can occupy the outermost energy level or
valence shell of a Representative Element is eight (the exception is helium,
which also exhibits a filled valence shell, but ony it requires only 2
electrons). As all Group VIII members have a filled valence shell, they have no
tendency to react in oxidation-reduction reactions.
