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Astatine
Atomic number: 85Mass: 210 uCategory: Halogen
About Astatine
Astatine is a radioactive chemical element that is the rarest naturally occurring element in the Earth's crust. It is a halogen and the heaviest naturally occurring element. At any given time, less than 1 gram exists naturally on Earth.
Properties
Period
6
Group
17
Block
P
Category
Halogen
Electronegativity
2.20 (Pauling)
Ionization Energy
920 kJ/mol
Melting Point
575 K (302°C)
Boiling Point
610 K (337°C)
Density
7 g/cm³
Oxidation States
-1, +1, +3, +5, +7
Electron Configuration
1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 4f¹⁴ 5s² 5p⁶ 5d¹⁰ 6s² 6p⁵
[Xe] 4f¹⁴ 5d¹⁰ 6s² 6p⁵
Shell 1:2e⁻
Shell 2:8e⁻
Shell 3:18e⁻
Shell 4:32e⁻
Shell 5:18e⁻
Shell 6:7e⁻
Real-World Uses
Cancer radiotherapy (At-211)
Research
Radioactive tracers
Nuclear medicine (experimental)
Physics research
Fun Fact
Astatine is so rare that less than 1 gram of it exists naturally on Earth at any moment — it constantly decays back into other elements!