Full Idea
There are chemically salient differences among the isotopes, best illustrated by the three isotopes of hydrogen: protium, deuterium and tritium, which show different rates of reaction, making heavy water poisonous where ordinary water is not.
Gist of Idea
Isotopes (such as those of hydrogen) can vary in their rates of chemical reaction
Source
Weisberg/Needham/Hendry (Philosophy of Chemistry [2011], 1.4)
Book Reference
'Stanford Online Encyclopaedia of Philosophy', ed/tr. Stanford University [plato.stanford.edu], p.10
A Reaction
[They cite Paul Needham 2008] The point is that the isotopes are the natural kinds, rather than the traditional elements. The view is unorthodox, but clearly makes a good point.