Why do metals tend to lose electrons and nonmetals tend to gain electrons when forming ions?

Question

Henry Antrim · Accepted Answer

Nonmetals are said to have high electronegativities because they typically gain electrons to form a complete outer shell.

While halogens, like chlorine, only need to gain one electron to form a complete outer shell—a far easier task than losing seven electrons—alkaline metals, on the other hand, would find it much easier to gain electrons than to lose them.

Transition metals are a little trickier to understand, but they share low electronegativities with a wide range of other metals.

Transition metals have #(n-1)d# and #ns# orbitals which have many electrons similar in energy, meaning that it is sometimes easy for many of those electrons to be lost. This is also the reason why metals have a high electrical conductivity (i.e. their electrons are can easily move from atom to atom).

Cooper Anderson · Answer

undefined Nonmetals have more electrons in their outermost energy level than metals, so gaining electrons enables them to reach a stable electron configuration. Conversely, metals have more electrons in their outermost energy level than nonmetals, so losing electrons makes it easier for them to achieve a stable electron configuration.