covalently

Covalently is an adverb used in chemistry to describe actions related to covalent bonding. Covalent bonding occurs when atoms share one or more pairs of electrons, typically between nonmetals, to achieve stable valence shells. The term is used to distinguish events and properties arising from covalent interactions from those arising from ionic or metallic bonding. Molecules whose atoms are held together primarily by covalent bonds are described as covalently bonded.

Formation involves overlapping atomic orbitals to share electron density. Bond polarity depends on the electronegativity difference between the bonded atoms: small differences yield nonpolar covalent bonds with near-equal sharing, moderate differences yield polar covalent bonds, and large differences produce ionic bonds. Examples of nonpolar covalent bonds include H2 and Cl2; polar covalent bonds include the C–H bond and the O–H bond in water. Covalent bonds can be single, double, or triple, corresponding to one, two, or three shared electron pairs and affecting bond length and strength.

Covalent bonding underlies the chemistry of organic compounds, biopolymers, and many minerals. In extended materials, covalent networks such as diamond or quartz consist of continuous covalent connections throughout the solid. In polymers, covalent bonds link monomer units into long chains, sometimes with crosslinks that influence mechanical properties. The term covalently is used in describing reactivity, localization of electrons, or the manner in which atoms join to form molecules and materials.