#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
  supertype:  substance__matter  that which has mass and occupies space; "an atom is the smallest indivisible unit of matter"
  subtype:  actinoid  allotrope  transuranic_element  noble_gas  rare_earth  metallic_element  nonmetal  transactinide  actinium  arsenic  astatine  boron  bromine  carbon  chlorine  fluorine  germanium  helium  hydrogen  iodine  krypton  lawrencium  mendelevium  neon  nitrogen  nobelium  oxygen  phosphorus  plutonium  radon  rutherfordium  selenium  silicon  sulfur  tellurium  unnilhexium  unnilquintium  unnilseptium  xenon  halogen  trace_element
  part:  atom  (physics and chemistry) the smallest component of an element having the chemical properties of the element
     part:  elementary_particle__fundamental_particle__fundamentalparticle__subatomicparticle  a particle that is less complex than an atom; regarded as constituents of all matter
     part:  nucleus__nucleu  the positively charged dense center of an atom
        part:  nucleon  a constituent (proton or neutron) of an atomic nucleus

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