Covalent bonds are chemical bonds in which two or more elements join together by sharing electrons, rather than transferring electrons, as is the case with ionic bonds. These bonds tend to occur with nonmetal elements of the periodic table. Water is a familiar substance comprised of hydrogen and oxygen linked by covalent bonds. read more
Ionic and covalent bonds are the two extremes of bonding. Polar covalent is the intermediate type of bonding between the two extremes. Some ionic bonds contain covalent characteristics and some covalent bonds are partially ionic. For example, most carbon-based compounds are covalently bonded but can also be partially ionic. read more