Chemical element · Atomic number 85
Astatine
Astatine in the periodic table: atomic number 85, electron configuration, atomic mass, physical data, oxidation states, media credit and visible sources.
Halogen
solid
[209.98715] u
Generated illustrationGenerated illustration, Quanta Study. Not a photograph of a sample.
Generated illustration of Astatine; the image does not show a sample of the element.
Highly radioactive element; no freely licensed photograph of a sample is available.
Code-native illustration with the Quanta Study mark inside the image; not a photograph, no AI model involved.
Atomic classification
Shell occupancy
Astatine in the Bohr shell model
This shows the electron distribution of the neutral atom in a simplified shell model.
- K · n=1
- 2 electrons
- L · n=2
- 8 electrons
- M · n=3
- 18 electrons
- N · n=4
- 32 electrons
- O · n=5
- 18 electrons
- P · n=6
- 7 electrons
- Electron configuration
- [Xe]6s2 4f14 5d10 6p5
- Electrons per shell
- 2 · 8 · 18 · 32 · 18 · 7
- Group
- 17
- Period
- 6
- Block
- P
- Element category
- Halogen
Physical and chemical properties
- Atomic mass
- [209.98715] u
- Standard state
- solid
- Density
- 7 g/cm³
- Melting point
- 575 K
- Boiling point
- not reported
- Electronegativity
- 2.2 (Pauling)
- First ionisation energy
- 9.5 eV
- Oxidation states
- +7, +5, +3, +1, -1
- Discovery
- 1940
Safety and periodic classification
Safety
Safe handling cannot be inferred from Astatine's position in the periodic table alone. Laboratory, classroom and disposal decisions must follow the documentation for the exact material and its safety data sheet.
Position and comparison
Astatine is in period 6, group 17 and the P block. Its direct neighbours by atomic number are Polonium and Radon. The recorded Pauling electronegativity is 2.2. Periodic trends are compared only through the separately sourced neighbouring values.
Sources and scope
PubChem attributes element data to sources including IUPAC, NIST and IAEA. Quanta stores the referenced snapshot locally and leaves unknown values unavailable.
Where Astatine sits among the 118 elements
The table compares the reported values for Astatine with every other element that carries the same value in the snapshot. A rank is not a judgement, it is orientation: it says how unusual this value is across the periodic table.
| Value | Astatine | Position in the data set |
|---|---|---|
| Melting point | 575 K | Rank 75 of 103 elements with a reported value. Highest: Carbon. |
| Density | 7 g/cm³ | Rank 50 of 96 elements with a reported value. Highest: Osmium. |
| Electronegativity (Pauling) | 2.2 | Rank 22 of 95 elements with a reported value. Highest: Fluorine. |
| Ionisation energy | 9.5 eV | Rank 20 of 102 elements with a reported value. Highest: Helium. |
All values and ranks come from the PubChem Periodic Table snapshot, retrieved on 2026-07-15. Elements without a reported value are excluded, so the population differs per row.
The neighbours of Astatine in the periodic table
- Place in the table
- Group 17, period 6, P block. Classified as halogen, solid at standard conditions.
- Direct neighbours
- Atomic number 85. Preceded by Polonium, followed by Radon.
- Same group
- Same number of outer electrons, and therefore similar reactivity to Fluorine, Chlorine, Bromine, Iodine, Tennessine.
- Discovery
- Recorded in the snapshot as: 1940. Who, where and under what circumstances is not part of that record, so this page carries the sourced year and no discovery narrative.
- Oxidation states
- +7, +5, +3, +1, -1. They follow from the electron configuration [Xe]6s2 4f14 5d10 6p5 and indicate which compounds to expect.
Go from looking up chemistry to remembering it.
Turn your notes into source-backed study cards and review them at the right time.
Starter stays free · no payment details