How do metals form positive ions in chemical reactions?

Metals form positive ions, or cations, by losing one or more of their valence electrons during chemical reactions. This process is driven by the fact that metal atoms typically have relatively low ionization energy, which is the energy required to remove an electron from an atom.123

When a metal reacts with a nonmetal, the metal atom transfers its valence electrons to the nonmetal atom. By losing these electrons, the metal atom achieves a stable electron configuration, often resembling that of a noble gas. The ease with which a metal loses these electrons depends on its position in the periodic table; generally, metals located toward the bottom left of the table have the lowest ionization energies and are the most chemically active, as their valence electrons are further from the positive nucleus and thus easier to remove.123

In addition to forming ionic compounds, the loss of valence electrons is fundamental to the metallic bond, where electrons become nonlocalized and wander freely throughout a metallic crystal, leaving behind positive metal ions.4