Each variety of hydrogen has its own personality and behaves differently in chemical reactions. For example, protium is more active than deuterium. By studying the behaviour of hydrogen isotopes, scientists started an entirely new branch of science, known as isotope chemistry. The chemistry we know has to do with elements as a whole, with all the isotopes of each, taken together. But isotope chemistry deals with separate isotopes. It enables investigators to look into the most intricate details of various chemical processes.
 

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