|-! bgcolor=gray | Properties|-||}In chemistry and physics, an atom (Greek ?????? or átomos meaning "the smallest indivisible particle of matter, i.e. something that cannot be divided") is the smallest particle still characterizing a chemical element.An atom consists of a dense nucleus of positively charged protons and electrically neutral neutrons, surrounded by a much larger electron cloud consisting of negatively charged electrons. An atom is electrically neutral if it has the same number of