Polonium Element Facts

The chemical element polonium is classed as a chalcogen and a metalloid. It was discovered in 1898 by Marie and Pierre Curie.

Marie Curie.

Marie Curie in 1883, 16 years old. Polonium was the first element she discovered, 15 years later.


Data Zone

Classification: Polonium is a chalcogen and a metalloid
Color: silvery-gray
Atomic weight: (209), no stable isotopes
State: solid
Melting point: 254 oC, 527 K
Boiling point: 960 oC, 1233 K
Electrons: 84
Protons: 84
Neutrons in most abundant isotope: 125
Electron shells: 2,8,18,32,18,6
Electron configuration: [Xe] 4f14 5d10 6s2 6p4
Density @ 20oC: 9.4 g/cm3
Show more, including: Heats, Energies, Oxidation, Reactions, Compounds, Radii, Conductivities
Atomic volume: 22.23 cm3/mol
Structure: simple cubic
Specific heat capacity 0.12 J g-1 K-1 0.12
Heat of fusion 13 kJ mol-1
Heat of atomization 142 kJ mol-1
Heat of vaporization 120 kJ mol-1
1st ionization energy 812 kJ mol-1
2nd ionization energy
3rd ionization energy
Electron affinity 180 kJ mol-1
Minimum oxidation number -2
Min. common oxidation no. -2
Maximum oxidation number 6
Max. common oxidation no. 4
Electronegativity (Pauling Scale) 2.0
Polarizability volume 6.8 Å3
Reaction with air mild, ⇒ PoO2
Reaction with 15 M HNO3
Reaction with 6 M HCl mild, ⇒ PoCl2
Reaction with 6 M NaOH none
Oxide(s) PoO2, PoO2
Hydride(s) PoH2
Chloride(s) PoCl2
Atomic radius 190 pm
Ionic radius (1+ ion)
Ionic radius (2+ ion)
Ionic radius (3+ ion)
Ionic radius (1- ion)
Ionic radius (2- ion)
Ionic radius (3- ion)
Thermal conductivity 0.2 W m-1 K-1
Electrical conductivity 0.7 x 106 S m-1
Freezing/Melting point: 254 oC, 527 K

Discovery of Polonium

Dr. Doug Stewart

Polonium was the first element Marie and Pierre Curie discovered.

They discovered polonium and then radium in 1898, while working in Paris, investigating radioactivity in pitchblende (uranium oxide).

At the time of the discovery they wrote: “We thus believe that the substance that we have extracted from pitchblende contains a metal never known before, akin to bismuth in its analytic properties. If the existence of this new metal is confirmed, we suggest that it should be called polonium after the name of the country of origin of one of us.”

In accordance with the Curies’ wishes, polonium is named after Poland, the country of Marie Curie’s birth.

The dangers of working with radioactive elements were not known when the Curies’ made their discoveries. Their laboratory notebooks from this time are so radioactive that they are now stored in a lead-lined case. (1)

Polonium from radon decay

Part of the uranium decay series. Three isotopes of polonium are produced in nature, either by the decay of radon gas itself or by the decay of atoms resulting from radon’s decay. Image by Tosaka.

Appearance and Characteristics

Harmful effects:

Polonium is harmful both through its chemical toxicity and its radioactivity. Polonium-210 is an alpha emitter. As such it is very hazardous if swallowed or inhaled. Exposure to polonium increases the risk of getting various cancers.


Polonium is a rare, silvery-gray, radioactive low-melting metalloid.

Polonium readily reacts with dilute acids, but only slightly with alkalis.

All of its isotopes are radioactive.

210Po emits a blue glow, as the air around it is excited by the decay products. 1 gram of Po emits as many alpha particles as 5 kilograms of radium. The energy released by polonium’s alpha decay is considerable and heats the volume around it. The energy released is so large (140 W/g) that a capsule containing about half a gram reaches a temperature above 500  oC.

Uses of Polonium

Polonium is used to eliminate static electricity produced during processes such as rolling paper, wire and sheet metal. However, beta decay sources are more commonly used as they are less dangerous.

210Po can be used as an atomic heat source but because of the isotope’s short half-life (138.4 days), it doesn’t provide power for long-term uses.

Polonium is also used in anti-static brushes to eliminate dust on photographic film. It is sealed in brushes to control the radioactive emissions.

Abundance and Isotopes

Abundance earth’s crust: Of the order of 1 part per quadrillion.

Abundance solar system: negligible

Cost, pure: per 100g

Cost, bulk: per 100g

Source: Polonium is a very rare element due to the short half-life of all its isotopes. It is found in uranium ores in minute quantities. It can be obtained by bombarding natural bismuth, 209Bi , with neutrons to give 210Bi, which then decays to 210Po via β decay. Approximately 100 g of polonium is synthesized each year.

Isotopes: Polonium has 29 isotopes whose half-lives are known, with mass numbers 190 to 218. None are stable. The most stable isotope is 209Po, with a half-life of 102 years.

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  1. this is a great website it helped me with my fact sheet thanks so much