85At[210]
Astatine
HalogensVery reactive non-metals with seven outer electrons. They form salts with metals.
[Xe] 4f¹⁴ 5d¹⁰ 6s² 6p⁵
- Atomic number
- 85
- Atomic mass
- [210]
- Protons
- 85
- Neutrons
- 125
- Electrons
- 85
- Shells
- 2, 8, 18, 32, 18, 7
- State at 25 °C
- Solid
- Position
- Group 17, period 6
Proton (+)Neutron (0)Electron (−)
Discovered byDale Corson, Kenneth MacKenzie and Emilio Segrè, 1940Emilio Segrè: 2 elements
Made by firing particles at bismuth. Its name comes from the Greek astatos, meaning unstable.
Did you know?
- It is the rarest naturally occurring element: probably less than a gram exists in Earth's crust at any time.
- No one has ever seen a visible piece of it.
Where it's found
- Tiny traces from uranium decay
What it's used for
- Research into targeted cancer therapy
Try it
There's no safe home experiment for Astatine. Explore it with the animated atom above instead.