Astatine

Astatine is a radioactive chemical element with the symbol At and atomic number 85. Astatine occurs on Earth as the result of decay of heavier elements, it decays so rapidly that very little is known about this element. Astatine is a highly radioactive element. It comes from the greek word astatos meaning unstable. The man pictured above is Emilio Segre and he was one of three people to discover the element Astatine in 1940 at the University of California Berkley. These three men created the element instead of searching for it in nature. Astatine was however found in nature three years later. Radioactive 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.
 * __Astatine__**
 * 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:**
 * 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 State:** Unknown



Uses
Astatine is far too rare to have any uses. Some research suggests a possible medical use, however. Astatine is similar to the elements above it in Group 17 (VIIA) of the periodic table, especially iodine. One property of iodine is that it tends to collect in the thyroid gland. The thyroid is a gland at the base of the neck that controls many body functions. Some researchers think that astatine will behave like iodine. If so, it could be used to treat certain diseases of the thyroid, such as thyroid cancer. When swallowed, the astatine would go to the thyroid. There, the radiation it gives off would kill cancer cells in the gland. No more than a millionth of a gram of astatine has ever been produced in the lab.

The newly formed astatine-211 is important in nuclear medicine.[83home] Once produced, astatine must be used quickly, as astatine-211 decays with a half-life of 7.2 hours; however, this is long enough to permit multi-step labeling strategies. astatine-211 can be used for targeted alpha particle radiotherapy, since it decays either via alpha decay to bismuth-207, or via electron capture to an extremely short-lived nuclide of polonium-211, which itself alpha decays.[83home]

**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.

Occurrence in nature
Astatine appears in the Earth's crust when the radioactive elements **uranium** and **thorium**decay. It can be made artificially only with great difficulty. By one estimate, no more than a millionth of a gram of astatine has ever been produced in the lab. 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.



Health effects of astatine The total amount of astatine in the earth's crust at any particular time is less than 30 grams and only a few micrograms have ever been artificially produced. This, together with its short lifetime, leaves no reason for considering the effects of astatine on human health. Astatine is studied in a few nuclear research laboratories where its high radioactivity requires special handling techniques and precautions. Astatine is a halogen and possibly accumulates in the thyroid like iodine. From a chemical point of view, one can speculate that its toxicity would mimic that of iodine.

Read more: [|http://www.lenntech.com/periodic/elements/at.htm#ixzz1uRgN5DbW] []