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Atomic symbol At
Atomic number 85
Atomic mass 210
Classification Halogen
Melting point 302°C575.15 K
575.6 °F
1,035.27 °R
Boiling point 337°C610.15 K
638.6 °F
1,098.27 °R
Density ~7 g/cm³
Electron shell 085 Astatine.png

Astatine is an element in group 7 of the periodic table. Only extremely minute amounts of astatine are present on earth at any one time, since it has no stable isotope and decays into other elements almost as soon as it is formed. Its name derives from a Greek word meaning 'unstable'.

Astatine's instability makes it extremely difficult to study, although its theoretical properties can be extrapolated from the other halogens. It has no uses, since it cannot exist for long enough to be used for anything.

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