What are isotopes?

Written by bkseljak on October 22, 2014. Posted in

Isotopes are atoms of the same element, which have the same chemical properties, but different mass because of different number of neutrons in the nucleus. 26 of 92 natural elements in the periodic system have only one natural stable isotope (such as sodium, aluminium, phosphorous or gold – monoisotopic elements), while most of them have two or more (such as hydrogen, sulphur, calcium or iron).