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.

Explanation:

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.

Capisce?