The Element Astatine
[Click for Isotope Data]
Atomic Number: 85
Atomic Weight: 210
Melting Point: 575 K (302°C or 576°F)
Boiling Point: Unknown
Density: about 7 grams per cubic centimeter
Phase at Room Temperature: Solid
Element Classification: Semi-metal
Period Number: 6 Group Number: 17 Group Name: Halogen
What's in a name? From the Greek word for unstable, astatos.
Say what? Astatine is pronounced as AS-teh-teen or as AS-teh-ten.
History and Uses:
Astatine was produced by Dale R. Carson, K.R. MacKenzie and Emilio Segrè by bombarding an isotope of bismuth, bismuth-209, with alpha particles that had been accelerated in a device called a cyclotron. This created astatine-211 and two free neutrons. This work was conducted at the University of California in 1940.
Small amounts of astatine exist in nature as a result of the decay of uranium and thorium, although the total amount of astatine in the earth's crust at any particular time is less than 30 grams. Due to its scarcity, astatine is produced when it is needed. A total of 0.05 micrograms (0.00000005 grams) of astatine have been produced to date.
Astatine's most stable isotope, astatine-210, has a half-life of 8.1 hours. It decays into bismuth-206 through alpha decay or into polonium-210 through electron capture.
Due to the small amounts produced and its short half-life, there are currently no uses for astatine outside of basic scientific research.
Estimated Crustal Abundance: Not Applicable
Estimated Oceanic Abundance: Not Applicable
Number of Stable Isotopes: 0 (View all isotope data)
Ionization Energy: 9.5 eV
Oxidation States: Unknown
3s2 3p6 3d10
4s2 4p6 4d10 4f14
5s2 5p6 5d10