1. Ionic compounds form when metals react with nonmetals, resulting in the transfer of electrons and formation of cations and anions bonded ionically. 2. Ionic compounds have high melting points and boiling points due to the strong electrostatic forces between cations and anions in the crystalline lattice structure. 3. Metallic bonds form when metal cations attract delocalized electrons in the "sea of electrons" that moves throughout the entire metallic crystal. This produces metallic properties like conductivity and ductility.