In ionic compounds, metals lose their valence electrons to form positively charged cations.
Explanation: Ionic compounds are formed when metals and nonmetals react. Metals, which are found on the left side of the periodic table, tend to have few valence electrons (usually 1 to 3) and can easily lose these electrons. When they do so, they become positively charged ions, known as cations. On the other hand, nonmetals, located on the right side of the periodic table, usually gain electrons to become negatively charged ions called anions. Thus, in the context of ionic compounds, it is the metals that lose their electrons to form cations.