The three divisions of bonds that occur: Covalent, ionic, and metallic bonds. A covalent bonds a chemical bond that involves sharing a pair of electrons between atoms in a molecule. A metal plus a nonmetal can form a covalent bond. They are nuetral molecules which do not conduct electricity, and have low melting and boiling points. A few examples of covalent bonds are HCl, SO2, and CO2. An ionic bond is a chemical bond in which one atom loses and electron to form a positive ion and the other atom gains an electron to form a negative ion. They are easily polar, conductable to electricity, have high melting points, dissolve easily in water, and have well-defined crystals. One atom has a high electronegativity vaule, while the other is relatively low; and one atom is a metal, while the other is nonmetal. An example of an ionic bond is magnesium oxide. Metallic bonds are the electromagnetic interaction between delocalized electrons, and the metallic nuclei within metals. Metallic bonding accounts for many physical properties of metals such as strength, malleability, ductility, thermal and electrical conductivity, opacity, and luster. An example of a metallic bond is the mercurous ion (Hg2+2).