Astatine

Atomic Number: 85
Symbol: At
Atomic Mass: (210) u
Number of Neutrons: 125
Melting Point: 302°C
Boiling Point: 336.8°C
Electrons per shell: 2.8.18.32.18.7
Electron configuration: [Xe] 4f¹⁴ 5d¹⁰ 6s² 6p⁵

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Astatine is the 85th element in the periodic table and it is a metalloid. It is the rarest naturally occurring element in the Earth's crust. It is only found as decayed products of other elements and astatine is only found ores in a few particle amounts. Astatine is so rare that it's most stable isotope (astatine-210) has a half-life of only 8.1 hours. This element is highly radioactive and unstable, which led to the name astatine, from the Greek word that meant "unstable." Astatine is so rare nobody in the entire world has ever seen it because it would vaporize itself with its own radioactive heat. But, hypothetically, you could buy 1 gram of astatine for 27 million. In 1940, three chemists named Dale R. Corson, Kenneth R. Mackenzie and Emilio Segre at the University of California discovered astatine.

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