Promethium

Chemical, physical and material properties and data of the chemical element Promethium.

Contents

Promethium - element symbol Pm, atomic number 61 - is a naturally occurring and otherwise artificially produced, radioactive, metallic, chemical element from the group of lanthanides (rare earths).

Promethium is the rarest representative of the lanthanides - and the only element in this group without stable isotopes. Natural occurrences are 100% composed of the nuclide Promethium-147 and total an estimated 1000 grams on Earth, mainly in some uranium ores. Pm-147 for research and engineering applications was artificially obtained from the spent fuel elements of nuclear reactors.

General Information about Promethium

Regular namePromethiumChemical symbolPmOther namesElement 61Historical namesIllinium, Florentium, Cyclonium, Prometheum (rejected proposals)Name meaning, originIn honor of the Greek hero Prometheus, who stole fire from Zeus and brought it to the peopleDiscovery (year)(1945) - J. A. Marinski, L. E. Glendenin, C. D. Coryell.OccurenceVery rarely; less than 1 kilogram total on Earth as Pm-147Position in the PSEPeriod 6, f-block, lanthanidesGroup membershipRare earth metals

Atomar Properties of Promethium

Atomic number Z61 = number of protonsStandard Atomic Weight146.9151385 (26)

Electron configuration of Promethium

1s	2s	2p	3s	3p	3d	4s	4p	4d	4f	5s	5p	5d	5f	6s	6p	6d	6f	7s	7p
2	2	6	2	6	10	2	6	10	5	2	6			2

Shorthand electron configuration of Promethium: [Xe] 4f⁵ 6s² .

Ionization Energies of Promethium

The following table lists the ionization energies IE (ionization potentials); the IE is the energy required in electron volt (eV) per atom to separate a given electron from an Promethium atom.

IE1	IE2	IE3	IE4
5.582	10.90	22.3	41.1

Isotopic Data of Promethium

An overview of the nuclides as well as the isotopic data and properties are listed on the following page: Promethium isotopes.

Chemistry of Promethium

Oxidation states+3Electronegativity1.1 (Pauling original)
1.13 (Pauling)Electron affinity0.129 eV
12.45 kJ mol^-1

Standard Electrode Potential

E⁰ (V)	Symbol	N_ox	Name Ox. Name Red.	Ox. Red.	e^-
-2.6	Pm	+ III + II	Promethium(III) cation Promethium(II) cation	Pm³⁺ ⇄ Pm²⁺	+ e^-
-2.30	Pm	+ III 0	Promethium(III) cation Promethium	Pm³⁺ ⇄ Pm (s)	+ 3 e^-
-2.2	Pm	+ II 0	Promethium(II) cation Promethium	Pm²⁺ ⇄ Pm (s)	+ 2 e^-

Material and Physical Properties

Melting point1042 °CEnthalpy of fusion (molar)7.13 kJ mol^-1Boiling point3000 °CEnthalpy of vaporization289 kJ mol^-1Density7.26 g cm^-3 (20 °C)

External Data, Identifiers

CAS registry number7440-12-2InChI =1S/PmInChIKeyVQMWBBYLQSCNPO-UHFFFAOYSA-NPubChem ID23944

Literature Sources and References

[1] - J. A. Marinsky, L. E. Glendenin, C. D. Coryell:
The Chemical Identification of Radioisotopes of Neodymium and of Element 61.
In: The Journal of the American Chemical Society, (1947), DOI 10.1021/ja01203a059.

[2] - NN:
Promethium, the New Name for Element 61.
In: Nature, (1948), DOI 10.1038/162175a0.

[3] - S. Cantrill:
Promethium puzzles.
In: Nature Chemistry, (2018), DOI 10.1038/s41557-018-0179-4.

[4] - Veronika Elkina, Mikhail Kurushkin:
Promethium: To Strive, to Seek, to Find and Not to Yield.
In: Frontiers in Chemistry, (2020), DOI 10.3389/fchem.2020.00588.

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Last update: 2023-01-09

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