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Astatine

Element 85 · Halogen

Specimen

Atomic number
85
Atomic mass
209.987
State at room temperature
Solid
Melting point
301.9 °C
Boiling point
Unknown
Density
7 g/cm³
Discovered
1940

Physical data from PubChem.1

Can I eat it?

In food and water
Never made in amounts you could eat. Astatine has never been made in an amount large enough to weigh. A visible amount would vaporize from its own radioactivity. 23

See every element.

The atom

At
ShellElectrons
1 (K) 2
2 (L) 8
3 (M) 18
4 (N) 32
5 (O) 18
6 (P) outermost 7
Total85

Configuration [Xe] 4f¹⁴ 5d¹⁰ 6s² 6p⁵

4f ↑ ↓ ↑ ↓ ↑ ↓ ↑ ↓ ↑ ↓ ↑ ↓ ↑ ↓
5d ↑ ↓ ↑ ↓ ↑ ↓ ↑ ↓ ↑ ↓
6s ↑ ↓
6p ↑ ↓ ↑ ↓ ↑
A shell diagram: each ring is an electron shell and each dot is one electron. The nucleus holds 85 protons. The outermost shell is shown in red. Electrons do not travel on rings: they fill orbitals, regions where an electron is likely to be found. The boxes are those orbitals for the electrons outside the Xe core, with one arrow per electron.

Related elements

Group 17
F Fluorine Cl Chlorine Br Bromine I Iodine Ts Tennessine

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Sources

  1. 1

    National Center for Biotechnology Information (PubChem), 2026. Periodic Table of Elements .

    Atomic mass, electron configuration, melting and boiling points, density and discovery year for all 118 elements.

  2. 2

    Royal Society of Chemistry, Periodic Table, 2026. Astatine - Element information, properties and uses .

    Reference page; its Biological role and Natural abundance sections are quoted.

    • Astatine can be obtained in a variety of ways, but not in weighable amounts.
  3. 3

    Los Alamos National Laboratory, Periodic Table of Elements, 2026. Astatine .

    • A weighable sample of the pure element is nearly impossible to assemble for study. Any visible portion of astatine would immediately vaporize itself because of its extreme radioactivity.