Periodic Table


Atomic number: 84
Atomic weight: 209
Symbol: Po
Group number: 16
Electronic configuration: [Xe].4f14.5d10.6s2.6p4


Polonium has more isotopes than any other element, all of which are radioactive. Polonium dissolves readily in dilute acids, but is only slightly soluble in alkalis.

Weight for weight it is about 2.5 x 1011 times as toxic as hydrocyanic acid (HCN). Polonium has been found in tobacco as a contaminant and in uranium ores.

General information

Discoveror: Marie Curie
Date discovered: 1898
Discovered at: France
Meaning of name: Named after "Poland" (birthplace of Marie Curie)

Physical data

Standard state: solid at 298 K
Colour: silvery
Density of solid at ambient temperature/kg m-3: 9196
Molar volume/cm3: 22.97

Radii /pm

Atomic: 135
Covalent (single bond):
Pauling radius for the ion [Po]-: no data

Valence shell orbital radius maxima (Rmax)
orbital s p d f


Both values are quoted on the Pauling scale.

Pauling: 2.0
Allred Rochow: 1.76

Crystal Structure

structure: cubic

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: 527
boiling point: 1235

Enthalpies /kJ mol-1

fusion: 13
vaporization: 111

single bond enthalpies:
Po-F Po-Cl Po-Br Po-I Po-Po
no data no data no data no data 187

Ionization enthalpies /kJ mol-1

Number Enthalpy


This section gives some data for naturally occurring isotopes.
Nominal mass Accurate mass % natural abundance

Further Information

Copyright 1997 Mark Winter
Department of Chemistry at the University of Sheffield, Sheffield S3 7HF, England.

The current version of this document is at http://www.shef.ac.uk/~chem/web-elements-I/Po.html