1 jan 1912 ano - Radioactivity P2

Descrição:

By 1912, almost 50 different radioactive substances had been found in the decay chains of thorium and uranium. American chemist Bertram Boltwood proposed several decay chains linking radioelements between uranium and lead. These were thought at the time to be new chemical elements, increasing the number of known "elements" and leading to speculations that their discoveries would undermine the periodic table.

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