Astatine

Astatine (At)

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.
Atomic Number85
Atomic Weight210
Mass Number193
Group17
Period6
Blockp
Protons85 p+
Neutrons108 n0
Electrons85 e-
Electron shell 085 Astatine.svg Animated Bohr Model Enhanced Bohr Model Bohr Model Orbital Diagram

Properties

Atomic Radius
Atomic Volume
Covalent Radius
147 pm
Metallic Radius
Ionic Radius
62 pm
Crystal Radius
76 pm
Van der Waals radius
202 pm
Density
Boiling Point
610 K
Melting Point
575 K
Electrons per shell2, 8, 18, 32, 18, 7
Electronegativity
2.2
Electrophilicity
2.8161454412824 eV/particle
Proton Affinity
Electron Affinity
Ionization Potential
9.31751 eV/particle
Heat of Vaporization
Heat of Fusion
Heat of Formation
Molar Heat Capacity
Specific Heat Capacity
Thermal Conductivity
Gas Basicity
Dipole Polarizability
42 a₀
C6 Dispersion Coefficient
Oxidation States-1, 1, 3, 5, 7
Color
Silver
Crystal Structure ()
Lattice Constant
Bulk Modulus
Electrical Resistivity
Electron Configuration[Xe] 4f14 5d10 6s2 6p5
Magnetic Ordering
Magnetic Susceptibility
PhaseSolid
Poisson Ratio
Shear Modulus
Young's Modulus
Allotropes
Alternate Names
Adiabatic Index
Appearance
Electric Conductivity
Critical Pressure
Critical Temperature
Curie Point
Electrical
Hardness
Magnetic Susceptibility
Magnetic
Neel Point
Neutron Cross Section
Neutron Mass Absorption
Gas Phase
Quantum Numbers
Refractive Index
Space Group
Speed of Sound
Superconducting Point
Thermal Expansion
Valence Electrons
Classification
CategoryHalogens, Halogens
CAS GroupVIIB
IUPAC GroupVIIA
Glawe Number98
Mendeleev Number110
Pettifor Number96
Geochemical ClassU/Th decay series
Goldschmidt Classsynthetic
Radioactivity
RadioactiveYes ☢️
Decay Mode
Half-Life
Lifetime
Abundance
Abundance in Earth's crust
Abundance in Oceans
Abundance in Human Body
Abundance in Meteor
Abundance in Sun
Abundance in Universena

Isotopes of Astatine

Stable Isotopes
Unstable Isotopes
193At 194At 195At 196At 197At 198At 199At 200At 201At 202At 203At 204At 205At 206At 207At 208At 209At 210At 211At 212At 213At 214At 215At 216At 217At 218At 219At 220At 221At 222At 223At

History

In 1869, existence of astatine was first predicted by Russian chemist Dmitri Mendeleev and called the element eka-iodine. In 1940, Dale R. Corson, Kenneth Ross MacKenzie, and Emilio Segrè isolated the element at the University of California, Berkeley. Instead of searching for the element in nature, the scientists created it by bombarding bismuth-209 with alpha particles. From the Greek astatos meaning unstable

DiscoverersD.R.Corson, K.R.MacKenzie, E.Segré
Discovery LocationUnited States
Discovery Year1940
Name OriginGreek: astatos (unstable).
Astatine is highly radioactive
Astatine is preferentially concentrated in the thyroid gland

Uses

The newly formed astatine-211 is important in nuclear medicine. Once produced, astatine must be used quickly, as it decays with a half-life of 7.2 hours. Astatine-211 can be used for targeted alpha particle radiotherapy, since it decays either via emission of an alpha particle. Since its isotopes have such short half-lives there are no commercially significant compounds of astatine.

Sources

Does not occur in nature. Similar to iodine. Produced by bombarding bismuth with alpha particles.