All practice pages/Interatomic theory/Elements

84Po[209]

Element 84, a metalloid

Polonium

The first element Marie Curie discovered, named for her homeland, and one of the deadliest substances known.

At a glance

Symbol
Po
Atomic number
84
Mass number of its longest-lived isotope
[209]
Group
16
Period
6
Family
metalloid
Electron configuration
[Xe] 4f¹⁴ 5d¹⁰ 6s² 6p⁴
Valence electrons
6
Electronegativity
2.00
Common ions
+2 and +4
Isotopes
none are stable; ²⁰⁹Po lasts longest, about 125 years, and ²¹⁰Po, with a half-life of 138 days, is the most common

On the table

Periodic table with Polonium highlighted123456789101112131415161718123456757-7189-103HHeLiBeBCNOFNeNaMgAlSiPSClArKCaScTiVCrMnFeCoNiCuZnGaGeAsSeBrKrRbSrYZrNbMoTcRuRhPdAgCdInSnSbTeIXeCsBaLaCePrNdPmSmEuGdTbDyHoErTmYbLuHfTaWReOsIrPtAuHgTlPbBiPoAtRnFrRaAcThPaUNpPuAmCmBkCfEsFmMdNoLrRfDbSgBhHsMtDsRgCnNhFlMcLvTsOg

Period 6, group 16. The other metalloids are tinted, and every cell opens its own article.

Electrons and bonding

Po

Six valence electrons, like oxygen and sulfur, yet polonium behaves as a metal. Its intense radioactivity heats its own samples and makes its chemistry hard to study.

Properties

State at 25 °C
solid
What it looks like
silvery-gray, intensely radioactive metal
Melting point
254 °C
Boiling point
962 °C
Density
9.32 g/cm³

Where it is found

Uranium ores hold only about 0.1 milligram per ton. Nearly all polonium is made in nuclear reactors by bombarding bismuth-209 with neutrons.

Discovery and name

Marie and Pierre Curie found it in 1898 in pitchblende, a uranium ore, months before they found radium. Marie named it after Poland, which was then divided among Russia, Prussia and Austria and did not exist as a country.

What it is used for

Devices that remove static electricity in factories, since its alpha particles make air conduct. It heated Soviet lunar rovers and, mixed with beryllium, served as a neutron source in early nuclear weapons.

In compounds

PoO₂polonium dioxidePbPolead polonideH₂Popolonium hydride

Handle with care

Swallowed or inhaled, a few micrograms can kill, because its alpha radiation destroys tissue from inside. Polonium-210 was used to poison Alexander Litvinenko in London in 2006.