Atoms will combine with each in order to become more chemically stable. Compound are formed between two atoms that hare outer energy levels. The two types of compounds that can be formed between atoms are ionic and covalent. Ionic compounds are formed between two nonmetal ion. Metals will lose electrons to form positive ions and nonmetals will gain electrons to form negative ions. These oppositely charge ions are very attracted to each other and form very strong bonds as a result. lonic compounds are characterized by crystalline structure, Two: or more pairs of electrons. The force of attraction between the nonmetals is relatively weak. Covalent compounds are characterized by i meting and boiling points and can be gases, liquids, or soft solids at room temperature.