Polonium (Po)
Post-transition metal · Radioactive
Polonium is a fiercely radioactive metalloid discovered by Marie and Pierre Curie — and named to protest the occupation of Marie's homeland, Poland. A single gram releases enough alpha radiation to glow and self-heat.
Position on the periodic table
Atomic properties
| Atomic number | 84 |
|---|---|
| Atomic mass | 209 amu |
| Electron configuration | 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6 6s2 4f14 5d10 6p4 |
| Noble gas shorthand | [Xe] 4f14 5d10 6s2 6p4 |
| Electrons per shell | 2, 8, 18, 32, 18, 6 |
| Valence electrons (outer shell) | 6 |
| Common oxidation states | +4, +2 |
| Electronegativity (Pauling) | 2 |
| Covalent radius (approx.) | 140 pm |
| First ionization energy | 812.1 kJ/mol |
| Electron affinity | 136 kJ/mol |
Physical properties
| State at 25 °C | Solid |
|---|---|
| Density | 9.196 g/cm³ |
| Melting point | 253.85 °C (527 K) |
| Boiling point | 961.85 °C (1235 K) |
| Appearance | silvery |
| Radioactive | Yes |
| Origin | Occurs naturally |
Electron configuration of polonium
Polonium's ground-state electron configuration is 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6 6s2 4f14 5d10 6p4, usually shortened to [Xe] 4f14 5d10 6s2 6p4. Its electrons occupy 6 shells (2, 8, 18, 32, 18, 6), placing it in period 6 of the p-block. The 6 outer-shell electrons drive its bonding behaviour. Explore it interactively in the electron configuration calculator.
Uses of polonium
- Static eliminators (historic)
- Compact heat sources for space probes (historic)
- Neutron initiators (historic)
Biological role: None — among the most toxic substances known when ingested.
Occurrence: Vanishingly rare traces in uranium ores; produced artificially in reactors.
Common compounds of polonium
PoO2
Polonium dioxide
History and discovery
Discovered: 1898 — Pierre Curie. Name origin: Named after Poland, Marie Curie's homeland, then erased from the map by partitions.
The Curies announced polonium in July 1898 — the first element they discovered, months before radium.
Safety notes
Severely radiotoxic — infamous from poisoning cases. Never encountered in normal life.
Educational context only — always follow your school's laboratory rules and never handle chemicals without proper supervision. See our disclaimer.
Practice questions
Quick practice: Polonium
1. What is the chemical symbol of Polonium?
2. What is the atomic number of Polonium?
3. Which category does Polonium belong to?
4. What is the state of Polonium at room temperature?
5. Which period of the periodic table is Polonium in?
Polonium FAQs
What is the atomic number of polonium?
Polonium's atomic number is 84 — every polonium atom has 84 protons in its nucleus.
What is the symbol for polonium?
Po. Named after Poland, Marie Curie's homeland, then erased from the map by partitions.
Is polonium a metal, nonmetal, or metalloid?
Polonium is classified as a post-transition metal.
What state is polonium at room temperature?
At about 25 °C, polonium is a solid. It melts at 253.85 °C.
How many valence electrons does polonium have?
Polonium has 6 electrons in its outer shell (shell pattern: 2, 8, 18, 32, 18, 6).
What is polonium used for?
Key uses include: static eliminators (historic); compact heat sources for space probes (historic); neutron initiators (historic).
Related elements
Keep working with this element
Spotted an error? Report a correction · Data sources