Chlorine has two principle isotopes, Cl-35 and Cl-37. How do you write out these isotopes in correct isotope notation?

1 Answer
Aug 30, 2016

The mass number of an isotope is usually supercripted to the upper left of the elemental symbol.


Sometimes, the atomic number, #Z# is subscripted to the lower left, however, the elemental symbol unequivocally identifies the element's identity, and thus identifies #Z#.

For common hydrogen isotopes, protium, deuterium, and tritium, we would write #""^1H, ""^2H, "and " ""^3H#, respectively.

For your problem we would write #""^35Cl, "and " ""^37Cl#; for both isotopes the elemental symbol specifies #Z=17#.