Why do Group 1 elements usually form ions with a positive one charge?

Group 1 elements, known as the alkali metals, form ions with a positive one (+1) charge because they possess a single valence electron in their outermost shell.12

These elements are highly reactive because they can achieve a stable, noble-gas configuration by losing this loosely held valence electron. According to the octet rule, atoms tend to combine in ways that allow them to attain the stable eight-outer-electron arrangement characteristic of noble gases.123

Because Group 1 elements have relatively low ionization energies, they can readily lose their single valence electron during chemical reactions to form stable cations. Removing additional electrons from the inner shells would require significantly higher energy, making the +1 charge the stable ionic form for these elements.456