and the sum of the protons and neutrons gives the atomic mass, the number of neutrons defines the isotope of that element. For example, most carbon (≈ 99 %) has 6 protons and 6 neutrons and is written ...

An isotope is named after the element and the mass number of its atoms. For example, carbon-12 is an isotope of carbon with a mass number of 12. The relative atomic mass of an element is the ...

Stable isotopes can be used by measuring their amounts and proportions in samples, for example in water samples. Naturally-occurring stable isotopes of water and other substances are used to trace the ...