Dictionary - N

  • newton: Unit of force in the international system (SI), equal to 105 dynes.
  • neutron: one of the fundamental particles that make up matter. Its mass is 1.675 x 10-27 kg, approximately 0.125% greater than that of the proton. It has no electric charge. It is a constituent particle of all nuclei except that of ordinary hydrogen.
  • core: central mass of a positively charged atom around which the orbital electrons are. It is composed of protons and neutrons and contains almost the entire mass of the atom.
  • mass number: the sum of the number of protons and neutrons contained in the nucleus of an atom. Atoms of the same element may have different mass numbers according to the isotope in question.