ELEMENTLE

Element 84 · Metal

Polonium

Period 6 · Group 16

Polonium is a chemical element with symbol Po and atomic number 84, discovered in 1898 by Marie Curie and Pierre Curie. A rare and highly radioactive element with no stable isotopes, polonium is chemically similar to bismuth and tellurium, and it occurs in uranium ores. Applications of polonium are few.

Three reasons Polonium stands out

  1. 1

    Highly radioactive, once used as heat source in space satellites.

  2. 2

    It was used to assassinate a former intelligence officer in London in 2006, causing a major international incident.

  3. 3

    It generates so much heat from its own radioactive decay that a small sample will glow visibly in the dark.

An intensely radioactive tribute to Poland

Marie and Pierre Curie found polonium while tracing the unexplained radioactivity of uranium ore. Alpha particles from polonium deposit enormous energy over very short distances, making material inside the body exceptionally dangerous. The name honored Marie Curie’s homeland at a time when Poland lacked independence.

Polonium at a glance
Atomic number / protons84
SymbolPo
Family (Elementle)Metal
Classification (PubChem)Metalloid
Period6
Group16
Atomic mass (u)208.98243
Standard stateSolid
Electron configuration[Xe]6s2 4f14 5d10 6p4
Reported oxidation states+4, +2
Electronegativity (Pauling)2
Atomic radius (pm)197
First ionization energy (eV)8.417
Electron affinity (eV)1.9
Density (g/cm³)9.32
Melting point527 K (253.85 °C)
Boiling point1235 K (961.85 °C)
Discovery (PubChem)1898

Values are reference data, not a specification for every temperature, pressure, or allotrope. Unknown properties are left unavailable. Superheavy-element predictions remain uncertain.

Sources & further reading

PubChem: Polonium · Polonium on Wikipedia

The introduction and original editorial story are adapted from Wikipedia contributors via Periodic-Table-JSON. Element descriptions and their adaptations are available under CC BY-SA 3.0. Numerical attributes use the PubChem periodic-table dataset, retrieved September 22, 2026.