Final answer:
Compounds are classified as ionic or covalent based on the presence of ionic or covalent bonds. Ionic compounds form from metals and nonmetals and have a crystalline structure, while covalent compounds involve sharing of electrons between nonmetals and are more flexible.
Step-by-step explanation:
Compounds are generally classified as either ionic or covalent based on the type of bonding they exhibit. Ionic compounds typically form when a metal reacts with a nonmetal, resulting in the net transfer of electrons and the formation of oppositely charged ions. These ions are held together by electrostatic forces in a crystalline structure. Covalent compounds, on the other hand, result from the sharing of electrons between two nonmetal atoms. This results in the formation of molecules with shared electron pairs, often leading to compounds with more flexible structures compared to the rigid structure of ionic compounds.
A simple method to determine whether a compound is ionic or covalent is to look at the elements involved. If the compound is made up of a metal and a nonmetal, it is likely ionic. If it is made up only of nonmetals, it tends to be covalent. However, this rule of thumb has exceptions and there exist polar covalent bonds where electrons are shared unequally, creating partial charges on the atoms.