astatine

• Description
• General information
• Physical data
• Radii
• Electronegativities
• Solid state structure
• Temperatures
• Enthalpies
• Ionization Enthalpies
• Isotopes
• Further information

Description

The longest-lived isotope, ²¹⁰At, has a half-life of only 8.3 hours. There are about 20 isotopes known, all of which are radioactive. Astatine is a halogen and possibly accumulates in the thyroid like iodine.

General information

Discoveror: Dale Corson, K.R. MacKenzie, and Emilio Segre
Date discovered: 1940
Discovered at: University of California, USA.
Meaning of name: From the Greek word "astatos" meaning "unstable"

Physical data

Standard state: solid at 298 K
Colour: metallic
Density of solid at ambient temperature/kg m^-3: no data
Molar volume/cm³: no data

Radii /pm

Atomic: 127
Covalent (single bond):
Pauling radius for the ion [At]^-: no data

Valence shell orbital radius maxima (R_max)

orbital	s	p	d	f
radius	104.0	119.4	50.8	17.2

Electronegativities

Both values are quoted on the Pauling scale.

Pauling: 2.2
Allred Rochow: 1.90

Crystal Structure

structure:

The following CrystalMaker image represents the solid state structure. For most elements, the most stable allotrope is illustrated. Try WebElements version 2 for interactive virtual reality and CHIME images.

Temperatures (/K)

melting point: 575
boiling point: 273

Enthalpies /kJ mol^-1

fusion: 12
vaporization: 30

single bond enthalpies:

At-F	At-Cl	At-Br	At-I	At-At
no data	no data	no data	no data	80

Ionization enthalpies /kJ mol^-1

Number	Enthalpy
1st	930

Isotopes

This section gives some data for naturally occurring isotopes.

Nominal mass	Accurate mass	% natural abundance
		nil

Further Information

• Additional information about WebElements 1.2.2
• This is a licensed copy (here is the full list) of WebElements 1.2.2 and contains a subset of the material contained within the main version of WebElements (version 2)
• For further information please try WebElements version 2
• Sheffield Chemdex: perhaps the largest internet chemistry directory
• Sheffield Chemputer: interactive chemistry calculators on the WWW