Covalent Bond

Interaction between atoms by which they “share” valence electrons in the outermost energy shells, thereby filling the outer shell of both atoms involved in the interaction. This occurs between atoms with similar high electronegativities (ΔX~0), resulting in highly localized bonding orbitals. For example, each hydrogen atom in a hydrogen gas molecule has a single electron. The valence energy level of a hydrogen atom is filled by two electrons; sharing their electrons allows each hydrogen atom to fill its energy shell.

Some or all content above used with permission from J. H. Wittke.