What is Promethium

Promethium (pronounced as pro-MEE-thee-em) is a radioactive metal with the chemical symbol Pm, belonging to the family of lanthanides as it does not exist naturally in the earth’s crust ^{[1, 3]}. It has twenty-nine isotopes with mass numbers ranging from 130 to 158 of which the most stable one is promethium-145 having a half-life of 17.7 years ^{[2, 4]}.

History

Origin of its Name: Promethium got its name from Prometheus, the Greek mythological titan who gifted fire to the human race after stealing it from the Gods ^[1].

Who Discovered it: Jacob .A. Marinsky, Charles D. Coryell, and Lawrence E. Glendenin were its discoverers.

When, Where, and How was it Discovered

Several attempts were believed to be made to find the existence of the new element as the well-known Czech chemist, Bohuslav Brauner speculated the possibility of another element between neodymium and samarium. In 1939, at the University of California, a 60-inch cyclotron was used for the same purpose. However, nothing was proved ^[1].

It was only in 1945 when Marinsky, Coryell, and Glendenin at the Oak Ridge, Tennessee used ion-exchange chromatography to separate the new element from the fission products of uranium fuel from a nuclear reactor ^[1].

Promethium Identification
Atomic number	61 [1]
CAS number	7440-12-2 [1]
Position in the periodic table [1]	Group	Period	Block
	Lanthanides	6	f

Properties and Characteristics of Promethium

General Properties
Relative atomic mass	[245] [1]
Atomic mass	245 atomic mass units [5]
Physical Properties
Color/appearance	Unknown [1]
Melting point/freezing point	1042°C (1908°F) [1]
Boiling point	3000°C, 5432°C [1]
Density	Unknown [1]
State at normal room temperature (solid/liquid/gas)	Solid [1]
Electrical conductivity	2×106 Sm-1[1]
Chemical Properties
Oxidation state/Oxidation number		(+2) +3 [1]

Atomic Data of Promethium (Element 61)

Uses of Promethium

The beta particles generated as a result of radioactive decay of promethium are used to make phosphor give off light that when converted into electricity by a solar cell provides power to radios, pacemakers, and guided missiles ^{[1, 2]}.

Interesting Facts

• It can be obtained from the byproducts of uranium fission ^[2].
• Promethium-147 is produced by bombarding neodymium-146 with neutrons through a chain of decays ^[2].
• The radioactive metal is believed to be present in the star of the Andromeda constellation ^[1].

Promethium Cost

Since the utility of the metal is based on its radioactive decay, it’s estimated to cost $ 0.5 per Curie (3.7 x 10¹⁰ decays per second).

References
1. http://www.rsc.org/periodic-table/element/61/promethium
2. https://education.jlab.org/itselemental/ele061.html
3. https://pubchem.ncbi.nlm.nih.gov/compound/promethium#section=Computed-Properties
4. https://www.chemicool.com/elements/promethium.html
5. http://periodictable.com/Properties/A/Valence.al.html
6. http://chemistry-reference.com/q_elements.asp?Symbol=Pm&language=en