A. The number of valence electrons determines how it reacts with other elements.
One to three valence electrons: The element behaves like a metal and reacts with non-metals.
Five to seven valence electrons: The element behaves like a non-metal and reacts with metals.
Four valence electrons: Elements at the top of the Group are non-metals, while those at the bottom are metals.
Eight valence electrons: Elements have a complete octet, so they are generally unreactive.
