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Extension of the periodic table beyond the seventh period Reference Libraries

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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
penuche
  • A fudgelike confection of brown sugar, cream or milk, and chopped nuts.
'Penuche' is a variant of 'panocha,' a coarse grade of sugar made in Mexico. 'Panocha' probably comes from the Spanish 'panoja, panocha,' ear of grain.
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