ASTATINE, At (85)

Astatine occurs on Earth as the decay product of various heavier elements. All of its isotopes are short-lived with the most stable being astatine-210, with a half-life of 8.1 hours. Elemental astatine has never been viewed as any macroscopic sample would be immediately vaporized by its radioactive heating.

ELEMENT BRIEF

1940 by Dale Corson, Kenneth Ross MacKenzie and Emilio Segrè, California, USA.

DISCOVERY

Greek 'astatos' meaning 'unstable'.

ETYMOLOGY

Astatine

ELEMENT

At

SYMBOL

85

ATOMIC NUMBER

7440-68-8

CAS NUMBER

ELEMENTAL SPECTRUM

Silver

ELEMENTAL COLOUR

-

REFRACTIVE INDEX

-

POISSON RATIO

33.148 cm³

MOLAR VOLUME

-

BRINELL HARDNESS

-

MOHS HARDNESS

-

VICKERS HARDNESS

-

SPEED OF SOUND

-

BULK MODULUS

-

SHEAR MODULUS

-

YOUNG MODULUS

ALLOTROPES

NONE

575.15 K, 302.00 °C

MELTING POINT

-

BOILING POINT

-

AUTOMATIC IGNITION

-

FLASHPOINT

-

CRITICAL TEMPERATURE

-

CRITICAL PRESSURE

2.000'000 W/(m K)

THERMAL CONDUCTIVITY

-

THERMAL EXPANSION

-

SPECIFIC HEAT

6.000 kJ/mol

HEAT FUSION

40.000 kJ/mol

HEAT VAPORISATION

-

HEAT COMBUSTION

-

CURIE POINT

-

NEEL POINT

-

ADIABATIC INDEX

Solid

PHASE

Conductor

ELECTRICAL TYPE

-

CONDUCTIVITY

-

RESISTIVITY

-

SUPERCONDUCTING POINT

-

MAGNETIC TYPE

-

MASS SUSCEPTIBILITY

-

MOLAR SUSCEPTIBILITY

-

VOLUME SUSCEPTIBILITY

Halogen

CLASSIFICATION

210.487'322'3

ATOMIC WEIGHT

120 pm

ATOMIC RADIUS

147 pm

COVALENT RADIUS SINGLE BOND

138 pm

COVALENT RADIUS DOUBLE BOND

138 pm

COVALENT RADIUS TRIPLE BOND

202 pm

VAN DER WAALS RADIUS

[Xe]6s²4f¹⁴5d¹⁰6p⁵

ELECTRON CONFIGURATION

Cubic, Primitive

CRYSTAL STRUCTURE

6.350 g/cm³

DENSITY AS SOLID

-

DENSITY AS LIQUID

-

DENSITY AS GAS

-

SPACE GROUP NAME

-

SPACE GROUP NUMBER

-

LATTICE ANGLES

-

LATTICE CONSTANTS

7

VALENCE

2.2

ELECTRONEGATIVITY

233.50 kJ/mol

ELECTRON AFFINITY

IONISATION ENERGY