#nucleus__nucleu  the positively charged dense center of an atom
  supertype:  midpoint__center__centre  a point equidistant from the ends of a line or the extremities of a figure
  part:  nucleon
  part of:  atom  (physics and chemistry) the smallest component of an element having the chemical properties of the element
     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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