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: 887.7±38.59 kJ·mol-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.