section_path: Types/Molecules
section_name: Molecules
paragraph_text: Molecules
  
  A molecule is an electrically neutral group of two or more atoms held together by chemical bonds. A molecule may be homonuclear, that is, it consists of atoms of one chemical element, as with two atoms in the oxygen molecule (O); or it may be heteronuclear, a chemical compound composed of more than one element, as with water (two hydrogen atoms and one oxygen atom; H O). A molecule is the smallest unit of a substance that still carries all the physical and chemical properties of that substance.