Word: mendeleeff
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Dates: during 1931-1931
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...Nucleus, The late great Dmitri Ivanovitch Mendeleeff arranged the 92 elements in a periodic table according to weight. The late Henry Gwyn-Jeffreys Moseley found that each atomic number corresponded to the number of negatively charged electrons outside the nucleus. Element No. 1, hydrogen, has one such electron; No. 2, helium, has two; lithium, No. 3, three. . . . For each negative electron the nucleus of an atom must contain a positively charged proton. And, except in hydrogen, all nuclei were found to contain more protons than were electrons around them. The additional necessary electrons were found in the nucleus. Lithium, with...
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