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Actinium
2009-07-09 17:04:18

Actinium is a radioactive chemical element. The symbol for Actinium is Ac and the atomic number is 89. Actinium was discovered in 1899 by French chemist André-Louis Debierne. It was the first non-primordial radioactive element to be isolated. Actinium is amongst a group of 15 similar elements within the periodic table that make up the actinoid series. This substance was also independently...

Word of the Day
omphalos
  • The navel or umbilicus.
  • In Greek archaeology: A central boss, as on a shield, a bowl, etc.
  • A sacred stone in the temple of Apollo at Delphi, believed by the Greeks to mark the 'navel' or exact center-point of the earth.
'Omphalos' comes from the ancient Greek.
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