#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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