Neutron matter is equivalent to a chemical element with atomic number 0, which is to say that it is equivalent to a species of atoms having no protons in their atomic nuclei. It is extremely radioactive; its only legitimate equivalent isotope, the free neutron, has a half-life of 10 minutes, which is approximately half that of the most stable known isotope of francium. Neutron matter decays quickly into hydrogen. Neutron matter has no electronic structure on account of its total lack of electrons.
