Adjective
Consisting of, or containing, one atom; as, the molecule of mercury is monatomic.
Having the equivalence or replacing power of an atom of hydrogen; univalent; as, the methyl radical is monatomic.
Source: Webster's dictionaryhelium and argon are monatomic gases Source: Internet
A defect in armchair-type tubes (which can conduct electricity) can cause the surrounding region to become semiconducting, and single monatomic vacancies induce magnetic properties. Source: Internet
Maxwell observed that the specific heat capacity of H 2 unaccountably departs from that of a diatomic gas below room temperature and begins to increasingly resemble that of a monatomic gas at cryogenic temperatures. Source: Internet
For these reasons and the small size of helium monatomic molecules, helium diffuses through solids at a rate three times that of air and around 65% that of hydrogen. Source: Internet
If the substance is one of the monatomic gases, (which have little tendency to form molecular bonds) the heat of fusion is more modest, ranging from 0.021 to 2.3 kJ per mole. Source: Internet
In this narrowest sense, the only pure paramagnet is a dilute gas of monatomic hydrogen atoms. Source: Internet