Periodic TableAstatine (At)
Astatine is a halogen with atomic number 85, in period 6 and group 17 of the periodic table. Its atomic mass is 210 u and its electron configuration is [Xe] 4f¹⁴ 5d¹⁰ 6s² 6p⁵. Solid at 25 °C.
Key facts
| Atomic number | 85 |
|---|---|
| Atomic mass | 210 u |
| Category | Halogen |
| Period | 6 |
| Group | 17 |
| Block | p |
| Electron configuration | [Xe] 4f¹⁴ 5d¹⁰ 6s² 6p⁵ |
| Electrons per shell | 2, 8, 18, 32, 18, 7 |
| Electronegativity (Pauling) | 2.2 |
| Oxidation states | −1, +1, +3, +5, +7common in bold |
| State at 25 °C | Solid |
| Melting point | 575 K301.85 °C |
| Boiling point | 610 K336.85 °C |
| Density | 7 g/cm³ |
Atomic properties
| First ionization energy | 9.318 eV |
|---|---|
| Electron affinity | 270.1 kJ/mol |
| Atomic radius | 145 pm |
| Covalent radius | 150 pm |
| Van der Waals radius | 202 pm |
| Common ions | At⁻ |
| Protons, neutrons, electrons | 85, 125, 85 |
Physical and thermal properties
| Molar volume | 33 cm³/mol |
|---|---|
| Heat of fusion | 6 kJ/mol |
| Heat of vaporization | 40 kJ/mol |
| Specific heat | --- |
| Thermal conductivity | 2 W/(m·K) |
| Thermal expansion | --- |
| Mohs hardness | --- |
| Young’s modulus | --- |
| Crystal structure | --- |
| Magnetic type | --- |
Identification and history
| CAS number | 7440-68-8 |
|---|---|
| Latin name | Astatum |
| Discovered by | D. Corson, K. Ross, E. Segrè · 1940 |
| Named by | --- |
Natural isotopes
Astatine has no stable isotopes: every isotope is radioactive.
Data checked against PubChem (NIH), IUPAC, the NIST Atomic Spectra Database and the IAEA (NUBASE and AME), the same data you see in the app.
A dash (---) means there is no reliable published measurement. The app never makes one up.
See Astatine in the app
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