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