Polonium (Po)
metalloidSolid
Standard Atomic Weight
[209]Electron configuration
[Xe] 6s2 4f14 5d10 6p4Melting point
253.85 °C (527 K)Boiling point
961.85 °C (1235 K)Density
9320 kg/m³Oxidation states
−2, +2, +4, +5, +6Electronegativity (Pauling)
2Ionization energy (1st)
Discovery year
1898Atomic radius
190 pmDetails
Polonium is a very rare, highly radioactive chalcogen below tellurium in group 16. It occurs naturally only in minute amounts as part of uranium and thorium decay chains, chiefly through isotopes such as ²¹⁰Po. Its chemistry combines metallic character with chalcogen behavior, and its significance comes mainly from intense alpha radioactivity rather than from ordinary materials use.
Polonium-210 is a low-melting, fairly volatile metal, 50% of which is vaporized in air in 45 hours at 55°C. It is an alpha emitter with a half-life of 138.39 days. A milligram emits as many alpha particles as 5 g of radium.
The energy released by its decay is so large (140W/g) that a capsule containing about half a gram reaches a temperature above 500C. The capsule also presents a contact gamma-ray dose rate of 0.012 Gy/h. A few curies (1 curie = 3.7 x 1010Bq) of polonium exhibit a blue glow, caused by excitation of the surrounding gas.
Polonium is readily dissolved in dilute acids, but is only slightly soluble in alkali. Polonium salts of organic acids char rapidly; halide amines are reduced to the metal.
Polonium was discovered by Marie Sklodowska Curie, a Polish chemist, in 1898. She obtained polonium from pitchblende, a material that contains uranium, after noticing that unrefined pitchblende was more radioactive than the uranium that was separated from it. She reasoned that pitchblende must contain at least one other radioactive element. Curie needed to refine several tons of pitchblende in order to obtain tiny amounts of polonium and radium, another radioactive element discovered by Curie. One ton of uranium ore contains only about 100 micrograms (0.0001 grams) of polonium. Due to its scarcity, polonium is usually produced by bombarding bismuth-209 with neutrons in a nuclear reactor. This forms bismuth-210, which has a half-life of 5 days. Bismuth-210 decays into polonium-210 through beta decay. Milligram amounts of polonium-210 have been produced by this method.
Polonium-210 is a very strong emitter of alpha particles. A single gram of polonium-210 creates 140 Watts of heat energy and is being considered as a lightweight heat source for thermoelectric power for spacecraft. Polonium-210 has a half-life of 138.39 days.
Polonium's most stable isotope, polonium-209, has a half-life of 102 years. It decays into lead-205 through alpha decay. Polonium-209 is available from Oak Ridge National Laboratory at the cost of about $3200 per microcurie.
Named after Poland, native country of Madam Curie. Polonium, also called Radium F, was the first element discovered by Curie in 1898 while seeking the cause of radioactivity of pitchblend from Joachimsthal, Bohemia. The electroscope showed it separating with bismuth.
Images
Properties
Physical
Chemical
Thermodynamic
Nuclear
Abundance
Reactivity
N/A
Crystal Structure
Electronic Structure
Identifiers
Electron Configuration Measured
Po: 4f¹⁴ 5d¹⁰ 6s² 6p⁴[Xe] 4f¹⁴ 5d¹⁰ 6s² 6p⁴1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 5s² 5p⁶ 4f¹⁴ 5d¹⁰ 6s² 6p⁴Atomic model
Isotopes change neutron count, mass, and stability — not the electron configuration of a neutral atom.
Schematic atomic model, not to scale.
Atomic Fingerprint
Emission / Absorption Spectrum
Isotope Distribution
No stable isotopes.
| Mass number | Atomic mass (u) | Natural abundance | Half-life |
|---|---|---|---|
| 211 Radioactive | 210.9866536 ± 0.0000014 | N/A | 516 ms |
| 193 Radioactive | 192.991026 ± 0.000037 | N/A | 399 ms |
| 194 Radioactive | 193.988186 ± 0.000014 | N/A | 392 ms |
| 212 Radioactive | 211.9888684 ± 0.0000013 | N/A | 294.4 ns |
| 188 Radioactive | 187.999416 ± 0.000021 | N/A | 270 us |
Phase / State
Reason: 228.9 °C below melting point (253.85 °C)
Schematic, not to scale
Phase transition points
Transition energies
Energy required to melt 1 mol at melting point
Energy required to vaporize 1 mol at boiling point
Energy required to sublime 1 mol at sublimation point
Density
At standard conditions
At standard conditions
Atomic Spectra
Showing 10 of 84 Atomic Spectra. Sorted by ion charge (ascending).
Lines Holdings ?
| Ion | Charge | Total lines | Transition probabilities | Level designations |
|---|---|---|---|---|
| Po I | 0 | 37 | 0 | 4 |
Levels Holdings ?
| Ion | Charge | Levels |
|---|---|---|
| Po I | 0 | 33 |
| Po II | +1 | 2 |
| Po III | +2 | 2 |
| Po IV | +3 | 2 |
| Po V | +4 | 2 |
| Po VI | +5 | 2 |
| Po VII | +6 | 2 |
| Po VIII | +7 | 2 |
| Po IX | +8 | 2 |
| Po X | +9 | 2 |
Ionic Radii
| Charge | Coordination | Spin | Radius |
|---|---|---|---|
| +4 | 6 | N/A | 94 pm |
| +4 | 8 | N/A | 108 pm |
| +6 | 6 | N/A | 67 pm |
Compounds
Isotopes (5)
Twenty five isotopes of polonium are known, with atomic masses ranging from 194 to 218. Polonium-210 is the most readily available. Isotopes of mass 209 (half-life 103 years) and mass 208 (half-life 2.9 years) can be prepared by alpha, proton, or deuteron bombardment of lead or bismuth in a cyclotron, but these are expensive to produce.
| Mass number | Atomic mass (u) | Natural abundance | Half-life | Decay mode | |
|---|---|---|---|---|---|
| 211 Radioactive | 210.9866536 ± 0.0000014 | N/A | 516 ms | α =100% | |
| 193 Radioactive | 192.991026 ± 0.000037 | N/A | 399 ms | α ≈100%β+ ? | |
| 194 Radioactive | 193.988186 ± 0.000014 | N/A | 392 ms | α ≈100%β+ ? | |
| 212 Radioactive | 211.9888684 ± 0.0000013 | N/A | 294.4 ns | α =100% | |
| 188 Radioactive | 187.999416 ± 0.000021 | N/A | 270 us | α ≈100%β+ ? |
Extended Properties
Covalent Radii (Extended)
Van der Waals Radii
Atomic & Metallic Radii
Numbering Scales
Electronegativity Scales
Polarizability & Dispersion
Phase Transitions & Allotropes
| Melting point | 527.15 K |
| Boiling point | 1235.15 K |
Oxidation State Categories
Advanced Reference Data
Screening Constants (15)
| n | Orbital | σ |
|---|---|---|
| 1 | s | 1.6232 |
| 2 | p | 4.5428 |
| 2 | s | 22.0782 |
| 3 | d | 13.428 |
| 3 | p | 23.2851 |
| 3 | s | 24.3813 |
| 4 | d | 36.3328 |
| 4 | f | 37.8416 |
| 4 | p | 36.3328 |
| 4 | s | 35.4784 |
Crystal Radii Detail (3)
| Charge | CN | Spin | rcrystal (pm) | Origin |
|---|---|---|---|---|
| 4 | VI | 108 | from r^3 vs V plots, | |
| 4 | VIII | 122 | from r^3 vs V plots, | |
| 6 | VI | 81 | Ahrens (1952) ionic radius, |
Isotope Decay Modes (71)
| Isotope | Mode | Intensity |
|---|---|---|
| 186 | A | 100% |
| 186 | p | — |
| 187 | A | 100% |
| 187 | B+ | — |
| 188 | A | 100% |
| 188 | B+ | — |
| 189 | A | 100% |
| 189 | B+ | — |
| 190 | A | 100% |
| 190 | B+ | — |
X‑ray Scattering Factors (516)
| Energy (eV) | f₁ | f₂ |
|---|---|---|
| 10 | — | 4.92763 |
| 10.1617 | — | 4.95784 |
| 10.3261 | — | 4.98823 |
| 10.4931 | — | 5.01881 |
| 10.6628 | — | 5.04957 |
| 10.8353 | — | 5.10634 |
| 11.0106 | — | 5.17368 |
| 11.1886 | — | 5.24191 |
| 11.3696 | — | 5.31104 |
| 11.5535 | — | 5.38108 |
Additional Data
Estimated Crustal Abundance
The estimated element abundance in the earth's crust.
2×10-10 milligrams per kilogram
References (1)
- [5] Polonium https://education.jlab.org/itselemental/ele084.html
Estimated Oceanic Abundance
The estimated element abundance in the earth's oceans.
1.5×10-14 milligrams per liter
References (1)
- [5] Polonium https://education.jlab.org/itselemental/ele084.html
Sources
Sources of this element.
Polonium is a very rare natural element. Uranium ores contain only about 100 micrograms of the element per ton. Its abundance is only about 0.2% of that of radium.
In 1934, scientists discovered that when they bombarded natural bismuth (209Bi) with neutrons, 210Bi, the parent of polonium, was obtained. Milligram amounts of polonium may now be prepared this way, by using the high neutron fluxes of nuclear reactors.
References (1)
- [6] Polonium https://periodic.lanl.gov/84.shtml
References
(9)
Data deposited in or computed by PubChem
The half-life and atomic mass data was provided by the Atomic Mass Data Center at the International Atomic Energy Agency.
Element data are cited from the Atomic weights of the elements (an IUPAC Technical Report). The IUPAC periodic table of elements can be found at https://iupac.org/what-we-do/periodic-table-of-elements/. Additional information can be found within IUPAC publication doi:10.1515/pac-2015-0703 Copyright © 2020 International Union of Pure and Applied Chemistry.
The information are cited from Pure Appl. Chem. 2018; 90(12): 1833-2092, https://doi.org/10.1515/pac-2015-0703.
Thomas Jefferson National Accelerator Facility (Jefferson Lab) is one of 17 national laboratories funded by the U.S. Department of Energy. The lab's primary mission is to conduct basic research of the atom's nucleus using the lab's unique particle accelerator, known as the Continuous Electron Beam Accelerator Facility (CEBAF). For more information visit https://www.jlab.org/
The periodic table at the LANL (Los Alamos National Laboratory) contains basic element information together with the history, source, properties, use, handling and more. The provenance data may be found from the link under the source name.
The periodic table contains NIST's critically-evaluated data on atomic properties of the elements. The provenance data that include data for atomic spectroscopy, X-ray and gamma ray, radiation dosimetry, nuclear physics, and condensed matter physics may be found from the link under the source name. Ref: https://www.nist.gov/pml/atomic-spectra-database
This section provides all form of data related to element Polonium.
The element property data was retrieved from publications.