#84 / 118
84Po[209]
Post-Transition Metalssolid at STPP-block

Polonium

Group: 16•Period: 6•Standard Atomic Weight: [209] u
Open Full Periodic TableView Bohr Model

Why is Polonium in this position?

Understanding the scientific rationale behind Polonium's position in the periodic table:

Group Assignment
Group 16

Belongs to Group 16 (Chalcogens) because it has 6 valence electrons (6s² 6p⁴).

Period Assignment
Period 6

Belongs to Period 6 because its outermost electrons occupy n=6.

Orbital Block
P-block

Belongs to the p-block because its valence electrons occupy 6p orbitals.

Chemical Category
Post-Transition Metals

Classified as a post-transition metal due to metallic electrical conductivity, although historically grouped with chalcogens.

Atomic Structure & Bohr Shell Model

Shell Distribution: [2, 8, 18, 32, 18, 6]

Bohr Atomic Shell Model(2, 8, 18, 32, 18, 6)

Hover or tap any shell orbit ring to inspect electron counts and 2n² capacities.

84 Protons (p⁺)125 Neutrons (n⁰)
KShell K: Electron 1 of 2Shell K: Electron 2 of 2LShell L: Electron 1 of 8Shell L: Electron 2 of 8Shell L: Electron 3 of 8Shell L: Electron 4 of 8Shell L: Electron 5 of 8Shell L: Electron 6 of 8Shell L: Electron 7 of 8Shell L: Electron 8 of 8MShell M: Electron 1 of 18Shell M: Electron 2 of 18Shell M: Electron 3 of 18Shell M: Electron 4 of 18Shell M: Electron 5 of 18Shell M: Electron 6 of 18Shell M: Electron 7 of 18Shell M: Electron 8 of 18Shell M: Electron 9 of 18Shell M: Electron 10 of 18Shell M: Electron 11 of 18Shell M: Electron 12 of 18Shell M: Electron 13 of 18Shell M: Electron 14 of 18Shell M: Electron 15 of 18Shell M: Electron 16 of 18Shell M: Electron 17 of 18Shell M: Electron 18 of 18NShell N: Electron 1 of 32Shell N: Electron 2 of 32Shell N: Electron 3 of 32Shell N: Electron 4 of 32Shell N: Electron 5 of 32Shell N: Electron 6 of 32Shell N: Electron 7 of 32Shell N: Electron 8 of 32Shell N: Electron 9 of 32Shell N: Electron 10 of 32Shell N: Electron 11 of 32Shell N: Electron 12 of 32Shell N: Electron 13 of 32Shell N: Electron 14 of 32Shell N: Electron 15 of 32Shell N: Electron 16 of 32Shell N: Electron 17 of 32Shell N: Electron 18 of 32Shell N: Electron 19 of 32Shell N: Electron 20 of 32Shell N: Electron 21 of 32Shell N: Electron 22 of 32Shell N: Electron 23 of 32Shell N: Electron 24 of 32Shell N: Electron 25 of 32Shell N: Electron 26 of 32Shell N: Electron 27 of 32Shell N: Electron 28 of 32Shell N: Electron 29 of 32Shell N: Electron 30 of 32Shell N: Electron 31 of 32Shell N: Electron 32 of 32OShell O: Electron 1 of 18Shell O: Electron 2 of 18Shell O: Electron 3 of 18Shell O: Electron 4 of 18Shell O: Electron 5 of 18Shell O: Electron 6 of 18Shell O: Electron 7 of 18Shell O: Electron 8 of 18Shell O: Electron 9 of 18Shell O: Electron 10 of 18Shell O: Electron 11 of 18Shell O: Electron 12 of 18Shell O: Electron 13 of 18Shell O: Electron 14 of 18Shell O: Electron 15 of 18Shell O: Electron 16 of 18Shell O: Electron 17 of 18Shell O: Electron 18 of 18PShell P: Electron 1 of 6Shell P: Electron 2 of 6Shell P: Electron 3 of 6Shell P: Electron 4 of 6Shell P: Electron 5 of 6Shell P: Electron 6 of 6PoZ = 84

Educational Note: This Niels Bohr planetary model visually illustrates principal quantum energy shells ($n=1, 2, 3\dots$) and electron counts. In modern quantum mechanics (Schrödinger model), electrons do not orbit in fixed circular planetary tracks, but exist as 3D probability clouds (orbitals: $s, p, d, f$) governed by the Heisenberg uncertainty principle.

Electron Shell Filling Breakdown

Shell K (n=1):2 / 2 electrons (100%)
Shell L (n=2):8 / 8 electrons (100%)
Shell M (n=3):18 / 18 electrons (100%)
Shell N (n=4):32 / 32 electrons (100%)
Shell O (n=5):18 / 50 electrons (36%)
Shell P (n=6):6 / 72 electrons (8%)
Aufbau Electron Configuration
1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 4f¹⁴ 5s² 5p⁶ 5d¹⁰ 6s² 6p⁴

Neutral ground state configuration. Valence electrons: 6.

Atomic & Quantum Properties

Electronegativity (Pauling)2 Pauling
1st Ionization Energy812.1 kJ/mol
Electron Affinity-183 kJ/mol
Atomic Radius (empirical)135 pm
Common Oxidation States+4, +2
Crystal StructureSimple Cubic (alpha)

Physical & Thermal Properties

Density at STP9.20 g/cm³
Melting Point254 °C (527 K)
Boiling Point962 °C (1235 K)
Magnetic OrderingParamagnetic
Discovery Year1898
Discovered ByMarie & Pierre Curie

Real-World Uses, Occurrence & Compounds

Major Industrial & Everyday Uses
  • Radioisotope thermoelectric generators (RTG) and thermal heat sources for lunar rovers (Lunokhod)
  • Antistatic brushes removing dust from high-end camera lenses and photographic film
  • Neutron trigger sources for early atomic nuclear weapons (Polonium-Beryllium triggers)
Occurrence in Nature

Extremely rare natural decay intermediate in the uranium-238 decay chain; produced artificially in nuclear reactors by neutron irradiation of Bismuth-209.

Etymology & Name Origin

Named after Poland (Latin 'Polonia'), the native homeland of Marie Skłodowska Curie

Important Chemical Compounds
PoO₂ (Polonium dioxide)
PoCl₄ (Polonium tetrachloride)
Interesting Chemical Facts
  • • Polonium-210 is one of the most lethally toxic substances known to science: one microgram is enough to deliver a fatal radiation dose to an adult.
  • • Polonium was used in the infamous 2006 assassination of former Russian intelligence officer Alexander Litvinenko in London via tea.
  • • Polonium is the only chemical element known to adopt a simple cubic crystal structure at standard conditions.
Safety & Handling Note

Dangerously radioactive alpha emitter; ingestion or inhalation causes catastrophic acute radiation syndrome.

Explore Neighborhood Elements

Same Group (Group 16):
#8O#16S#34Se#52Te#116Lv
Same Period (Period 6):
#55Cs#56Ba#57La#58Ce#59Pr#60Nd#61Pm#62Sm#63Eu#64Gd#65Tb#66Dy#67Ho#68Er#69Tm#70Yb#71Lu#72Hf#73Ta#74W#75Re#76Os#77Ir#78Pt#79Au#80Hg#81Tl#82Pb#83Bi#85At#86Rn