Astatine

Metalloid · atomic number 85

85210AtAstatineSolidMetalloid

Astatine is a very rare radioactive chemical element with the chemical symbol At and atomic number 85. It occurs on Earth as the decay product of various heavier elements. All its isotopes are short-lived; the most stable is astatine-210, with a half-life of 8.1 hours.

Properties of Astatine

Element category	Metalloid
Atomic number	85
Atomic mass	210 u
Phase at STP	Solid
Group	17
Period	6
Block	p
Electron configuration	[Xe] 4f14 5d10 6s2 6p5
Electrons per shell	2, 8, 18, 32, 18, 7
Electronegativity (Pauling)	2.2
Melting point	575 K (302 °C)
Boiling point	610 K (337 °C)
Density	6.35 g/cm3
Discovered by	Dale R. Corson

← Polonium · Periodic table · Radon → Rn

About the metalloid group

In-between elements that behave as semiconductors: silicon, germanium and boron underpin electronics, glass and solar cells.

Data: Periodic-Table-JSON (CC BY-SA 3.0) · stored statically on our server. https://en.wikipedia.org/wiki/Astatine

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