Neutron: definition in chemistry
Neutron: An electrically neutral subatomic particle found in the nucleus, with a mass slightly greater than that of a proton.
Neutrons add mass to an atom without changing its charge, and different numbers of neutrons give the different isotopes of an element. Together with protons, they are held in the nucleus by the strong nuclear force, and the balance between neutrons and protons decides whether a nucleus is stable. The neutron was discovered by James Chadwick in 1932, and in nuclear reactors neutrons trigger the splitting of uranium-235 nuclei.
Examples
- Ordinary hydrogen (hydrogen-1) has no neutrons
- Carbon-12 has 6 neutrons and carbon-14 has 8
- Uranium-238 has 92 protons and 146 neutrons
- A free neutron decays with a half-life of about 10 minutes
On the periodic table
The table does not list neutron numbers, but you can estimate them by subtracting the atomic number from the atomic mass rounded to a whole number.