Periodic Table of Elements

85

Astatine

209.99

Astatine was isolated by Dale R. Corson, Kenneth Ross MacKenzie, and Emilio Segrè in 1940 at the University of California, Berkeley. The scientists created it by bombarding bismuth-209 with alpha particles. The name "astatine" comes from the Greek word astatos, meaning "unstable".

Name: Astatine
Symbol: At
Atomic number: 85
Atomic weight: 209.99
State: solid
Group, period, block: 17, 6, p
Color: metallic
Classification: halogen
Electron configuration: 6s2 4f14 5d10 6p5
2,8,18,32,18,7

Physical properties

Density: no data
Melting point: 575 K, 302 C, 576 F
Boiling point: 610 K, 337 C, 639 F

Atomic properties

Oxidation states: -1, +1, +3, +5, +7
Electronegativity: 2.2 (Pauling scale)
Ionization energies: 1st: 887.738.59 kJmol-1
Covalent radius: 150 pm
Van der Waals radius: 202 pm
  • At
  • Electron Configuration

Isotopes

There are twenty isotopes of astatine exist. All of these isotopes are radioactive.