What does covalence mean?
Covalence is the chemical principle behind most of the matter we encounter: it describes the bond that forms when two atoms share one or more pairs of electrons rather than exchanging them outright. This sharing allows each atom to achieve a stable outer shell of electrons, which is why molecules like water, carbon dioxide, and DNA owe their structure to covalent bonds. The noun itself appears mainly in technical chemistry writing, where scientists may speak of single, double, or triple covalences depending on how many electron pairs are shared; the related term 'covalent bond' is far more familiar outside specialist circles. Covalence contrasts with electrovalence (or ionic bonding), in which electrons are transferred completely from one atom to another. Understanding covalence means understanding why some substances hold together rigidly while others dissolve, melt, or react — a concept first clarified in the early twentieth century by pioneers of modern atomic theory such as G. N. Lewis.
nounThe chemical bond formed between atoms by the sharing of one or more pairs of electrons; more generally, the number of electron pairs an atom shares with neighboring atoms.
- (chemistry) A chemical bond in which two atoms share one or more pairs of electrons.
- (chemistry) The valence of an atom as expressed through shared electron pairs; the number of such bonds an atom forms.
"The two hydrogen atoms are held together by a single covalence, each sharing its lone electron with the other."
"In a water molecule, each hydrogen atom forms one covalence with the central oxygen atom."
"Carbon's ability to form four covalences is what makes organic chemistry — and life itself — possible."
Used mainly in chemistry texts when referring to several individual bonds or to the total combining capacity of an atom across multiple bonds.
"Nitrogen typically satisfies three covalences in forming ammonia."
Every molecule in your body is glued together not by magnets or glue, but by atoms politely sharing electrons — and chemists call that sharing covalence.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of covalence
The word covalence derives from the Latin prefix 'co-' ('together') combined with 'valentia', rooted in the Latin verb 'valere', meaning 'to be strong or have worth'. It emerged in English in the late nineteenth century alongside the development of structural chemistry, as scientists sought precise terms for how atoms combine. The same Latin root gives us words like 'valid', 'value', and 'convalesce', all carrying a sense of strength or capacity.
Related word forms
How covalence is actually used
A technical term used almost exclusively in chemistry and physics; in everyday scientific writing, the adjective 'covalent' and phrases like 'covalent bond' are far more common than the noun 'covalence' itself.
Easily confused with covalence
Valence is the broader combining capacity of an atom, whereas covalence specifically refers to that capacity fulfilled by sharing electron pairs rather than by transferring them.