What is Nuclear notation? — Physics

Definition 19.1 High School Physics · Chapter 19 — The Nucleus and Radioactivity

A nucleus contains $Z$ protons (charge $+e$ each) and $N$ neutrons (no charge), $A = Z + N$ nucleons in all; it is written ${}^{A}_{Z}\mathrm{X}$ , where $\mathrm X$ is the chemical symbol, $Z$ the atomic number and $A$ the mass number. A species specified by $A$ and $Z$ is a nuclide; nuclides with the same $Z$ but different $A$ are isotopes of one element: same chemistry (the electron cloud sees only $Ze$ ), different nuclei and stability.

Examples

Example 19.2 (Hydrogen and carbon)

Hydrogen has three isotopes: ${}^{1}_{1}\mathrm{H}$ (a lone proton), ${}^{2}_{1}\mathrm{H}$ (deuterium: one proton, one neutron), unstable ${}^{3}_{1}\mathrm{H}$ (tritium: two neutrons). Natural carbon: mostly ${}^{12}_{6}\mathrm{C}$ ( $6$ protons, $6$ neutrons), $1.1\%$ of ${}^{13}_{6}\mathrm{C}$ , and one atom in $10^{12}$ of unstable ${}^{14}_{6}\mathrm{C}$ ( $8$ neutrons), hero of Example 19.17.

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