Nuclear Physics
Atomic Number
The atomic number (symbol Z) is the number of protons found in the nucleus of every atom of a particular chemical element. The atomic number uniquely identifies a chemical element and determines its position in the periodic table. In an uncharged atom, the atomic number is also equal to the number of electrons.
Neutron
The neutron is an electrically neutral subatomic particle that, together with protons, forms atomic nuclei. It has a rest mass of 1.00866491595 u (≈ 939.565 MeV/c²) and a magnetic moment of –1.913 μN. Discovered by James Chadwick in 1932, free neutrons undergo beta decay with a mean lifetime of about 878 seconds.