## Chemistry: A Molecular Approach (3rd Edition)

The isotopes can be denoted by 2 different notations: 1. First notation : $^{A}_{Z}X$ Here, X is the chemical symbol, A is the mass number, and Z is the atomic number. 2. Second notation : $X$-$A$ This is is the chemical symbol (or chemical name X) followed by a dash and the mass number of the isotope.
Examples are denoted using the neon isotopes: 1. First notation : $^{20}_{10}Ne$ , $^{21}_{10}Ne$, $^{22}_{10}Ne$ 2. Second notation: $Ne$-20, $Ne$-21, $Ne$-22 neon-20, neon-21, neon-22