#atom  (physics and chemistry) the smallest component of an element having the chemical properties of the element
  supertype:  substance__matter  that which has mass and occupies space; "an atom is the smallest indivisible unit of matter"
  subtype:  ion  isotope  monad  carbon_atom  hydrogen_atom  free_radical
  part:  elementary_particle  nucleus
  part of:  chemical_element__element  any of the more than 100 known substances (of which 92 occur naturally) that cannot be separated into simpler substances and that singly or in combination constitute all matter
  part of:  molecule  (physics and chemistry) the simplest structural unit of an element or compound

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