ionic
Ionic bonds form only between metals and nonmetals. Thats because metals want to give up electrons, and nonmetals want to gain electrons. Find sodium Na in the Figure below . Sodium is an alkali metal in group 1. Like all group 1 elements, it has just one valence electron. If sodium loses that one electron, it will have a full outer energy level, which is the most stable arrangement of electrons. Now find fluorine F in the periodic table Figure below . Fluorine is a halogen in group 17. Like all group 17 elements, fluorine has seven valence electrons. If fluorine gains one electron, it will also have a full outer energy level and the most stable arrangement of electrons.