At

Astatine

Identification

CAS Number: 7440-68-8

Discovery Year: 1940

Discoverer: D.R.Corson, K.R.MacKenzie, E.Segré

Discovery Location: United States

Properties

Atomic Mass: 210 →Density: 7 g/cm³ →

Atomic Dimensions

Atomic Radius (Rahm): 247.00000000000003 pm

Covalent Radius: 150 pm →

Van der Waals Radius: 202 pm

Thermodynamics

Melting Point: 575 K →Boiling Point: 610 K →

Electronic Structure

Electron Config: [Xe] 4f14 5d10 6s2 6p5

Block: p

Period: 6 →Group: 17 →Electronegativity: 2.2 →Electron Affinity: 2.8 eV →

Oxidation States: -1, +1, +3, +5, +7

Abundance & Geochemistry

Geochemical Class: U/Th decay series

Goldschmidt Class: synthetic

About

Radioactive halogen element. Occurs naturally from uranium and thorium decay. At least 20 known isotopes. At-210, the most stable, has a half-life of 8.3 hours. Synthesized by nuclear bombardment in 1940 by D.R. Corson, K.R. MacKenzie and E. Segre at the University of California.

Isotopes

At-210 210 ☢ 8.10 h

At-211 211 ☢ 7.21 h