The smallest unit of an [[원소,element]].

See also
 [[원자질량단위,atomic_mass_unit(amu)]]

MKL
[[원자핵,atomic_nucleus]]
[[핵자,nucleon]]
[[입자,particle]]
[[분자,molecule]]
[[물질,substance,matter]] ... [[물질,matter]]
[[물리학,physics]] ... [[물리학physics]]
[[화학,chemistry]]

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영단어:
[[아톰,atom]]

NN:원자
WpKo:원자