monatomic

American  

[mon-uh-tom-ik] / ˌmɒn əˈtɒm ɪk /

adjective

Chemistry.

1. having one atom in the molecule.

2. containing one replaceable atom or group.

3. having a valence of one.

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monatomic British  

/ ˌmɒnəˈtɒmɪk, ˌmɒnəʊəˈtɒmɪk /

adjective

1. (of an element) having or consisting of single atoms

   argon is a monatomic gas

2. (of a compound or molecule) having only one atom or group that can be replaced in a chemical reaction

3. a less common word for monovalent

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Other Word Forms

• monatomically adverb

Etymology

Origin of monatomic

First recorded in 1840–50; mon- + atomic

Example Sentences

The ions that we have discussed so far are called monatomic ions, that is, they are ions formed from only one atom.

From Textbooks • Feb. 14, 2019

For example, the pure metalloids form covalent crystals like the nonmetals, but like the metals, they generally do not form monatomic anions.

From Textbooks • Feb. 14, 2019

The noble gases are all monatomic, whereas the other nonmetal gases—hydrogen, nitrogen, oxygen, fluorine, and chlorine—normally exist as the diatomic molecules H2, N2, O2, F2, and Cl2.

From Textbooks • Feb. 14, 2019

Reinhardt, A. & Doye, J. P. K. Free energy landscapes for homogeneous nucleation of ice for a monatomic water model.

From Nature • Nov. 7, 2017

The molecule of iodine, for example, is monatomic at 1200� C., but becomes diatomic at the ordinary temperature.

From The Mechanism of Life by Leduc, Stéphane