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Seldom found in nature. | Atomic Number: | 85 | Atomic Symbol: | At | | Atomic Weight: | 210 | Electron Configuration: | 2-8-18-32-18-7 | | Shells: | 2,8,18,32,18,7 | Filling Orbital: | 6p5 | | Melting Point: | 302oC | Boiling Point: | 337oC | | Description: | Radioactive member of the halogen group. | | Uses: | Does not occur in nature. Similar to iodine.
Produced by
bombarding bismuth with alpha particles. |
History(Gr. astatos, unstable) Synthesized in 1940 by D.R. Corson, K.R.
MacKenzie, and E. Segre at the University of California by bombarding bismuth
with alpha particles.
IsotopesThe longest-lived isotopes, with naturally occurring uranium
and thorium isotopes, and traces of 217At are equilibrium with 233U and 239Np
reulting from interation of thorium and uranium with naturally produced
neutrons.
OccurenceThe total amount of astatine present in the earth's crust,
however, is less than 1 oz.
Properties- Astatine can be produced by bombarding bismuth with energetic alpha
particles to obtain the relatively long-lived 209-211At, which can be distilled
from the target by heating in air.
- The "time of flight" mass spectrometer has been used to confirm that this
highly radioactive halogen behaves chemically very much like other halogens,
particularly iodine.
- Astatine is said to be more metallic than iodine, and, like iodine, it
probably accumulates in the thyroid gland.
UsesWorkers at the Brookhaven National Laboratory have recently used
reactive scattering in crossed molecular beams to identify and measure
elementary reactions involving astatine.
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