Stable isotope Astatine (At)

Isotope Atomic Mass Half-life Mode of Decay Nuclear Spin
At-207 206.98578 1.81 hours EC to Po-207; α to Bi-203 9/2
At-208 207.98657 1.63 hours EC to Po-208; α to Bi-204 6
At-209 208.98616 5.40 hours EC to Po-209; α to Bi-205 6
At-210 209.987126 8.10 hours EC to Po-210; α to Bi-206 5
At-211 210.98748 7.21 hours EC to Po-211; α to Bi-207 9/2

Properties of Astatine

Name Astatine
Symbol At
Atomic number 85
Atomic weight 210
Standard state Solid at 298 °K
CAS Registry ID 7440-68-8
Group in periodic table 17
Group name Halogen
Period in periodic table 6
Block in periodic table p-block
Color Metallic
Classification Semi-metallic
Melting point 302 °C
Boiling point 230 °C
Thermal conductivity 1.7 (estimate) W/(m·K)
Electronegativity 2.2
Heat of vaporization About 40 kJ·mol-1
Heat of fusion About 6 (per mole astatine atoms) kJ·mol-1
Density of solid 6.4 (estimated) g/cm3 
Electronic configuration [Xe]4f145d106s26p5
Oxidation states in aqueous solution -1, 0, +5, +7
Most stable isotope At-210