Isotone

Nuclear species with the same number of neutrons in the nucleus but a different number of protons (which makes it a different element) are called isotones of that element.

All matter is made up of atoms in various arrangements. Atoms are composed of protons, neutrons, and electrons. Each proton has a charge of +1, each electron a charge of -1, and each neutron has no charge (neutral charge--neutron). When nuclear scientists study different nuclear species, it's useful to look at nuclei with the same number of neutrons, but changing the number of protons, which changes the chemical nature of the nucleus. This concept isn't used nearly as often as the related concept of isotope, which have the same number of protons but a different number of neutrons. The mnemonic for remembering which is which is that isotone has an n, while isotope has a p for proton.

An example to illustrate the point would be different isotones with 20 neutrons. There are a lot of stable nuclear species with 20 neutrons because 20 is a magic number of neutrons.: , , , , and

PhET on building isotopes

The University of Colorado has graciously allowed us to use the following PhET simulation.This simulation explores how adding different numbers of protons and neutrons make different isotones and isotones: