History of subatomic physics the mostly empty volume of atoms. In 1918, Rutherford confirmed that the hydrogen nucleus was a particle with a positive charge, which he named the proton. By then, Frederick Soddy's researches of radioactive elements, and experiments of J. J. Thomson and F.W. Aston conclusively demonstrated existence of isotopes, whose nuclei have different masses in spite of identical atomic numbers. It prompted Rutherford to conjecture that all nuclei other than hydrogen contain chargeless particles, which he named the neutron. Evidences that atomic nuclei consist of some smaller particles (now called "nucleons") grew; it became obvious that, while protons repulse each other
Even and odd atomic nuclei 162, and 165+ can also alpha decay.) This gives a total of 101 stable nuclides with odd mass numbers. There are another 9 radioactive primordial nuclides (which by definition all have relatively long half lives, greater than 80 million years) with odd mass numbers. Odd-mass-number nuclides are fermions, i.e. have half-integer spin. Generally speaking, since odd-mass-number nuclides always have an even number of either neutrons or protons, the even-numbered particles usually form part of a "core" in the nucleus with a spin of zero. The nucleon with the odd number (whether protons or neutrons) then form a second core with