Physics and Chemistry. Consisting of single atoms rather than molecules; of a thickness or depth of one atom.

Consisting of five atoms; containing five atoms per molecule. Also: pentabasic, pentahydric (now rare); †pentavalent (obsolete).

of three atoms, triatomic, adj.

(a) Containing four atoms in the molecule. †(b) = tetravalent, adj., quadrivalent, adj. n. Obsolete. †(c) = tetrahydric, adj. Obsolete.

(a) Having three atoms in the molecule. †(b) = trivalent, adj. Obsolete. (c) Containing three hydroxyl groups (OH); = trihydric, adj.1

Consisting of, or having, two atoms; specifically applied to compounds containing two replaceable atoms of hydrogen; sometimes used as = divalent.

Containing or consisting of six atoms of some substance; having six replaceable hydrogen atoms; also = hexavalent, adj.

Consisting of eight atoms; containing eight atoms per molecule.

containing or equivalent to seven atoms.

Chemistry. Monatomic. Also: monomolecular. Now disused.