Electropositivity

Electropositivity is a measure of an element's ability to donate electrons, and therefore form positive ions. Mainly, this is an attribute of metals, meaning that for the most part, the greater the metallic character of an element, the greater the electropositivity. Therefore the alkali metals are most electropositive of all. This is because they have a single electron in their outer shell and, as this is relatively far from the nucleus of the atom, it is easily lost; in other words, these metals have low ionization energies.

Electropositivity is opposed to electronegativity: the ability of an element to attract electrons. While electronegativity increases along periods in the periodic table, and decreases down groups, electropositivity decreases along periods and increases down groups.

Electropositive metals are also utilized as shark repellents, since they generate measurable voltages in a seawater electrolyte relative to a shark.