covalence vs covalency

covalence and covalency both are nouns.

Word	Noun	Adjective	Verb	Adverb
covalence	Yes	No	No	No
covalency	Yes	No	No	No

As nouns, covalence and covalency are synonyms defined as:

covalence and covalency: valence characterized by the sharing of electrons in a chemical compound; the number of pairs of electrons an atom can share

covalence (noun)	covalency (noun)
valence characterized by the sharing of electrons in a chemical compound; the number of pairs of electrons an atom can share	valence characterized by the sharing of electrons in a chemical compound; the number of pairs of electrons an atom can share