Astatine was first made in 1940 by Dale Corson, Kenneth MacKenzie and Emilio Segre at the University of California, Berkeley. They bombarded the element bismuth with alpha particles in a cyclotron and detected a new radioactive element that filled the last empty place among the halogens in the periodic table. Its name comes from the Greek astatos, meaning unstable, and it is indeed extremely unstable, with its most stable isotope having a half-life of only about eight hours. Astatine is the rarest naturally occurring element on Earth, since only a tiny amount exists in the crust at any time, produced by the decay of heavier elements. Its short life makes it hard to study, but researchers have investigated one of its isotopes for targeted cancer therapy.
Before and after
- from 1940 to 1948Rise of Lehi
- c. 1940sRise of Postmodernism
- from 1940 to 1957Rise of Forest Brothers
- from 1940 to 1991Occupation of the Baltic states
- 1940Discovery of astatine
- 19401940 becomes the warmest year on record
- 4 January 1940Birth of Gao Xingjian
- 19 January 1940Construction of Dublin Airport
- 24 January 1940Birth of Joachim Gauck
More in Science & technology
- 1931Kurt Godel proves his incompleteness theorems
- 1933Karl Jansky detects radio waves from the Milky Way
- 4 March 1936First flight of LZ 129 Hindenburg
- 1 February 1942Launch of Voice of America
- October 1943Streptomycin, the first antibiotic that works against tuberculosis, is discovered
- 1944Avery, MacLeod and McCarty show that DNA carries genes
The era
This moment belongs to the Modern era (1914 CE to 1945 CE), world wars and a changing world. You can also browse everything in the 20th century.