Atomic number 85 occurs as chemical element in the periodic table that has the symbol At & atomic number 85. This radioactive element occurs naturally from uranium and thorium decay and is the heaviest of the halogens.

Notable characteristics
This extremely radioactive element has been confirmed by mass spectrometers to behave chemically much prefer more halogens, especially iodine (it probably accumulates in the thyroid gland like iodine). At is thought to exist as further metallic than iodine. Research worker at a Brookhaven National Laboratory have performed experiments that have identified & measured simple responses that require at.

By having a conceivable exception of francium, astatine is a rarest naturally occurring element by owning the aggregate total within Globe's crust figured to exist as less than Unity oz (28 g) at any in of these case; this numbers to less than one teaspoon of the element.

History
At (Greek astatos meaning "unstable") was first synthesized around 1940 by Dale R. Corson, K. R. MacKenzie, and Emilio Segrè of the University of California, Berkeley by barraging bismuth with alpha particles. An earliest title for the element was alabamine (Ab).

Occurrence
Atomic number 85 is by bombarding atomic number 83 by using up-and-coming alpha particles to obtain comparatively long-long-lasting At-209 - At-211, which might so become distilled from the target by heating when in contact with air.

Isotopes
Atomic number 85 has 41 known isotopes, all of which are then radioactive; the longest-lived isotope is ²¹⁰At which has the half-life of 8.Ace hours. A shortest-lived isotope is ²¹³At which has the half-life of 125 nanoseconds.