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[mon-uh-tom-ik] /ˌmɒn əˈtɒm ɪk/
adjective, Chemistry
having one atom in the molecule.
containing one replaceable atom or group.
having a valence of one.
Also, monoatomic.
Origin of monatomic
1840-50; mon- + atomic
Related forms
monatomically, adverb Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2015.
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Examples from the web for monatomic
  • And monatomic hydrogen will all be gone in only a few days.
  • Atoms and monatomic ions produce colors by excitation and decay of electrons in their atomic orbitals.
  • Measurements could be taken that would show these characteristics for polyatomic gases, monatomic gases, and gas mixtures.
  • Secondly, liquid metals and alloys are typically monatomic.
  • If monatomic gas, generally smooth spectrum above edge.
  • These monatomic gases are obtained by fractionation of liquid air.
  • monatomic and diatomic positive ions of both nitrogen and oxygen were also present.
British Dictionary definitions for monatomic


adjective (chem)
(of an element) having or consisting of single atoms: argon is a monatomic gas
(of a compound or molecule) having only one atom or group that can be replaced in a chemical reaction
a less common word for monovalent
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition
© William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins
Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
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monatomic in Medicine

monatomic mon·a·tom·ic (mŏn'ə-tŏm'ĭk)

  1. Occurring as single atoms.

  2. Having one replaceable atom or radical.

  3. Univalent.

mon'a·tom'ic·al·ly adv.
The American Heritage® Stedman's Medical Dictionary
Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.
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