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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
upstander
  • A person who stands up for something, as contrasted to a bystander who remains inactive.
  • One of the upright handlebars on a traditional Inuit sled.
The word 'upstander' in the first sense here is a play on the word 'bystander' and the idea of 'standing up' for something.