THALLIUM My element was Thallium. It is atomic number 81. It has 81 protons and electrons and 123 neutrons. Thallium has a mass of 204.3833 atomic mass units. Its symbol is Tl. It resides in Group IIIA of the periodic table. That is the aluminum family. Thallium has a bluish color after exposure to the air. It is a very soft and malleable metal. It has an electron configuration of 1s22s23s23p64s23d104p65s24d105…showed first 75 words of 459 total…

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