What does covalency mean?
Covalency is a term from chemistry that describes the number of covalent bonds an atom can form — that is, how many pairs of electrons it shares with neighbouring atoms. When chemists say that carbon has a covalency of four, they mean a carbon atom typically shares four electron pairs, whether as four single bonds or some combination of single, double, and triple bonds. The word also carries a broader sense, describing the condition of atoms or compounds being linked through shared rather than transferred electrons. Covalency sits alongside the older concept of valency but is used specifically where electron-sharing is meant, distinguishing it from electrovalency, which involves the complete transfer of electrons in ionic bonding. The term appears chiefly in textbooks, examination syllabi, and technical literature, and it remains especially common in British educational contexts. Understanding covalency offers a compact way of predicting molecular shape, bonding patterns, and the behaviour of elements across the periodic table.
nounThe state or property of being covalent; in chemistry, the number of covalent bonds an atom forms with other atoms, equal to the number of shared electron pairs it participates in. More broadly, the quality of involving shared electron pairs between atoms.
- In chemistry, the number of covalent bonds (shared electron pairs) an atom forms with other atoms.
- The state or condition of being held together by covalent bonds; covalent character or linkage generally.
"Carbon has a covalency of four, forming four single bonds with hydrogen atoms in methane."
"Oxygen typically shows a covalency of two, as seen in water molecules."
"The high covalency of the silicon-oxygen bond helps explain the stability of quartz."
Rarely needed, as covalency usually refers to a specific measurable value for a given element or compound.
"The table compares the maximum covalencies of elements in the second period."
Every atom has a social circle — its covalency is simply how many bonds it's willing to make, and carbon's famous number is four.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of covalency
Covalency derives from 'covalent', a term coined in the early twentieth century from Latin roots: the prefix 'co-' meaning 'together' and 'valere' meaning 'to be strong or have power'. It emerged as chemists distinguished between atoms bonded by shared electrons and those joined by electrostatic attraction, pairing 'covalency' with the contrasting term 'electrovalency'. Related words sharing the same root include valence and the adjective covalent itself.
Related word forms
How covalency is actually used
A technical term used almost exclusively in chemistry and related sciences, particularly in British textbooks and older pedagogical literature, where 'covalency' was traditionally preferred over the now more common 'valency' when discussing shared-electron bonding specifically.
Easily confused with covalency
Covalence and covalency are near-synonymous terms for the same chemical concept, with covalence slightly more common in American usage and covalency more common in British texts; neither differs in meaning.
Electrovalency refers to bonding by complete transfer of electrons (ionic bonding), whereas covalency refers to bonding by sharing electron pairs.