085Metalloid · Group 17 · Period 6
Astatine
Astatine (At) is element 85, a metalloid in the p-block — group 17, period 6. It is a solid at room temperature with 6 electron shells (2, 8, 18, 32, 18, 7) and an atomic mass of 210 u.
- Atomic mass
- 210.0 u
- Phase · STP
- solid
- Melting
- 575 K · 302 °C
- Boiling
- 610 K · 337 °C
- Electronegativity
- 2.2
- Density
- 6.35 g/cm³
Photograph — Chemical ELements A Virtual Museum, CC BY 3.0 <https://creativecommons.org/licenses/by/3.0> source: https://images-of-elements.com/astatine.php
Identity
- Atomic number
- 85
- Standard atomic weight
- 210.0 u
- Category
- Metalloid
- Group
- 17 · Halogens
- Period
- 6
- Block
- p-block
- Oxidation states
- 7, 5, 3, 1, -1
Physical properties
- Melting point
- 575 K · 302 °C
- Boiling point
- 610 K · 337 °C
- Density
- 6.35 g/cm³
- Molar heat capacity
- —
- Atomic radius
- 202 pm
- Electron affinity
- 233 kJ/mol
Atomic structure
85protons
125neutrons
85electrons
7valence e⁻
- Noble-gas notation
- [Xe] 4f14 5d10 6s2 6p5
- Full configuration
- 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6 6s2 4f14 5d10 6p5
- Electrons per shell
- 2, 8, 18, 32, 18, 7
Periodic trends
Where Astatine ranks across all 118 elements.
Discovery
- Discovered
- 1940
- Discovered by
- Dale R. Corson
- Named by
- —
- Appearance
- unknown, probably metallic