Actinium
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Actinium is a chemical element, having the chemical symbol Ac.
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Its atomic number (the number of protons) is 89. It has a Standard Atomic Weight of 227, and is typically found as a solid in its elemental form.
Actinium is considered to be a member of the "Transition metal" class of elements, has a boiling point of 3,198 °C, and a melting point of 1,051 °C.
History
Actinium has been discovered in 1899 by André-Louis Debierne, and independently by F. Giesel in 1902[1]
References
- ↑ David R. Lide, ed., CRC Handbook of Chemistry and Physics, Internet Version 2005, <http://www.hbcpnetbase.com>, CRC Press, Boca Raton, FL, 2005. I.