Tritium deuterium, another isotope of hydrogen, by Ernest Rutherford, Mark Oliphant, and Paul Harteck. However, their experiment could not isolate tritium, which was later accomplished by Luis Alvarez and Robert Cornog, who also realized tritium's radioactivity. Willard F. Libby recognized that tritium could be used for radiometric dating of water and wine. Tritium Tritium ( or ; symbol ' or ', also known as hydrogen-3) is a radioactive isotope of hydrogen. The nucleus of tritium (sometimes called a triton) contains one proton and two neutrons, whereas the nucleus of protium (by far the most abundant hydrogen isotope) contains one proton and
Isotope 40 different species referred to as "radioelements" (i.e. radioactive elements) between uranium and lead, although the periodic table only allowed for 11 elements from uranium to lead. Several attempts to separate these new radioelements chemically had failed. For example, Soddy had shown in 1910 that mesothorium (later shown to be Ra), radium (Ra, the longest-lived isotope), and thorium X (Ra) are impossible to separate. Attempts to place the radioelements in the periodic table led Soddy and Kazimierz Fajans independently to propose their radioactive displacement law in 1913, to the effect that alpha decay produced an element two places to the