At
Astatine Symbol (At)
Astatine is element 85 of the periodic table. Copy its symbol At and see its atomic weight, electron configuration and physical properties.
What does At mean?
At is the chemical symbol for astatine, element number 85 in the periodic table. Astatine is a halogen in group 17, period 6. It is a solid at room temperature and was discovered in 1940.
Codes and properties
| Chemical symbol | At |
|---|---|
| Atomic number (Z) | 85 |
| Mass number (no standard atomic weight) | [210] |
| Group / period | 17 / 6 |
| Element category | halogen |
| Electron configuration | [Xe]6s² 4f¹⁴ 5d¹⁰ 6p⁵ |
| State at 20 °C | Solid |
| Oxidation states | 7, 5, 3, 1, -1 |
| Electronegativity (Pauling) | 2.2 |
| Melting point | 575 K (301.85 °C) |
| Density | 7 g/cm³ |
| Discovered | 1940 |
How to type At
- Plain text: type
At— element symbols are ordinary Latin letters, with the first letter capitalised and the second lowercase. - Subscripts in formulas: use Unicode subscript digits (₀₁₂₃₄₅₆₇₈₉) for formulas such as H₂O — copy them from the chemistry keyboard.
- LaTeX: write
\mathrm{At}in math mode, or use the mhchem package:\ce{At}. - HTML:
At; for subscripts use<sub>, e.g.H<sub>2</sub>O.
Frequently asked questions
What is the chemical symbol for astatine?
The chemical symbol for astatine is At.
What is the atomic number of astatine?
Astatine has atomic number 85, meaning each atom has 85 protons.
What is the electron configuration of astatine?
The ground-state electron configuration of astatine is [Xe]6s² 4f¹⁴ 5d¹⁰ 6p⁵.
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Reference: Astatine on PubChem (NIH)