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Astatine [At] locate me
CAS-ID: 7440-68-8
An: 85 N: 125
Am: [210] g/mol
Group No: 17
Group Name: Halogen
Block: p-block  Period: 6
State: solid at 298 K
Colour: metallic Classification: Semi-metallic
Boiling Point: 610K (337°C)
Melting Point: 575K (302°C)
Density: unknown
Discovery Information
Who: D.R.Corson, K.R.MacKenzie, E.Segre
When: 1940
Where: United States
Name Origin
Greek: astatos (unstable).
 "Astatine" in different languages.
Sources
Does not occur in nature. Produced by bombarding bismuth with alpha particles. The longest-lived isotope, 210At, has a half-life of only 8.3 hours. There are about 20 isotopes known, all of which are radioactive. Astatine is a halogen and possibly accumulates in the thyroid like iodine.
Uses
None.
History
first synthesized in 1940 by Dale R. Corson, K. R. MacKenzie, and Emilio Segre at the University of California, Berkeley by barraging bismuth with alpha particles.
An earlier name for the element was alabamine (Ab).
Notes
With the possible exception of francium, astatine is the rarest naturally occurring element with the total amount in Earth's crust estimated to be less than 1 oz (28 g) at any one time; this amounts to less than one teaspoon of the element. Astatine is in "The Guinness Book of Records" as the rarest element on Earth.
Hazards
This highly radioactive element has been confirmed by mass spectrometers to behave chemically much like other halogens, especially iodine (it would probably accumulate in the thyroid gland like iodine). Astatine is thought to be more metallic than iodine.