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
Highly radioactive, once used as heat source in space satellites.
2
It was used to assassinate a former intelligence officer in London in 2006, causing a major international incident.
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.
Recognizing Polonium in Elementle
If Polonium is the mystery element, guesses below atomic number 84 point up and guesses above it point down. Its symbol is Po: a green letter matches the same position in that symbol, while a yellow letter belongs in another position.
The family clue turns green for metal guesses. Compare Bismuth (Bi), number 83 and Lead (Pb), number 82: they share the family clue, but their atomic numbers and symbols help you tell them apart.
Values are reference data, not a specification for every temperature, pressure, or allotrope. Unknown properties are left unavailable. Superheavy-element predictions remain uncertain.
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.