What does the superscript of an isotope notation mean?

1 Answer
anor277
May 6, 2018

This represents the NUMBER of nuclear particles....

Explanation:

Let's take a simple example, i.e. for hydrogen, the MOST abundant element in this universe. Most hydrogen nuclei contain the ONE nuclear particle, i.e. one proton....and we would represent this ISOTOPE as #""^1H#, #"protium"#, to reflect its mass.

A smaller percentage of hydrogen atom necessarily contain the DEFINING proton, and ALSO a neutron...to give the #"deuterium isotope"#....i.e. #""^2H#..here in the nucleus there are one proton (necessarily) and ALSO ONE neutron.

And an even smaller percentage of hydrogen atoms, contain the #"tritium isotope"#, i.e. #""^3H#. How many neutrons does this isotope contain?

And so the superscripted number is the number of #"nucular particles"#, protons, and neutrons. The atomic symbol defines #Z#, the atomic number. To a first approximation (which does not work so well for hydrogen), the chemistry of the isotopes are identical.

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