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<CENTER><P><B><FONT SIZE=+2>Chemical 
Fact Sheet</FONT></B></P></CENTER>

<CENTER><P><B><FONT SIZE=+3>Astatine</FONT></B></P></CENTER>

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<TH>Chemical Abstract Number (CAS #)</TH>

<TD>
<FONT SIZE=-1>7440-68-8</FONT></TD>
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<TR>
<TH>Analytical Methods</TH>

<TD><FONT SIZE=-1>200.8 - 6020
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<TR>
<TH>Atomic Symbol</TH>

<TD>A<FONT SIZE=-1>t</FONT></TD>
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<TD>
<CENTER><P>
<B>Synopsis from the<A HREF="http://www.crcpress.com">
 CRC Handbook of Chemistry and Physics 
92nd Edition 2011-2013</a></B></P></CENTER>

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<TD><FONT SIZE=-1>Astatine — (Gr. astatos, unstable), At; at. wt. (210); at. no. 85; m.p.
302 °C; valence probably 1, 3, 5, or 7. Synthesized in 1940 by
D. R. Corson, K. R. MacKenzie, and E. Segre at the University
of California by bombarding bismuth with alpha particles.
The longest-lived isotope, 210At, has a half-life of only 8.1
hours. Thirty-six other isotopes and isomers are now known.
Minute quantities of 215At, 218At, and 219At exist in equilibrium
in nature with naturally occurring uranium and thorium
isotopes, and traces of 217At are in equilibrium with 233U and
239Np resulting from interaction of thorium and uranium with
naturally produced neutrons. The total amount of astatine
present in the Earth’s crust, however, is probably less than 1
oz. 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 it in
air. Only about 0.05 μg of astatine has been prepared to date.
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. The interhalogen
compounds AtI, AtBr, and AtCl are known to form,
but it is not yet known if astatine forms diatomic astatine molecules.
HAt and CH3At (methyl astatide) have been detected.
Astatine is said to be more metallic that iodine, and, like iodine,
it probably accumulates in the thyroid gland.</FONT></TD>
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