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Last updated date: 09th Apr 2024
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Promethium Element

The Promethium element is represented by the symbol Pm. Promethium is a lanthanide and a rare earth metal. All the isotopes of promethium are radioactive in nature. Promethium metal emits beta radiation. As it is a rare metal, so its chemical and physical characteristics are not well known. Promethium salts have a pink or red colour that gives a pale blue-green glow to the ambient air. Promethium metal was discovered by Mariinsky in 1945.

  • Electronic configuration- [Xe]4f56s2

  • The atomic number of promethium- 61

  • The atomic mass of promethium- 145gmol-1

Physical Properties of Promethium

Promethium is the f-block element that belongs to the group lanthanides and period 6. It is solid at 20°C.

  • Melting point- 1042°C, 1908°F, 1315 K

  • Boiling point- 3000°C, 5432°F, 3273 K

  • The density of promethium- 7.26

Chemical Properties of Promethium

  • Chemically, promethium is a lanthanide, when mixed with other elements, forms salts. It shows only one stable state of oxidation of +3. 

  • Since traces of the element are extremely scarce in nature, the element is typically synthesized to produce promethium-147 by bombarding enriched uranium with thermal neutrons

  • Promethium salts have pink or red colour with a pale blue-green light that colours the surrounding air.

Promethium Uses

  1. Most promethium is used only for research purposes except for promethium-147, which can be found outside laboratories. It is obtained in milligram quantities as oxide or chloride. This isotope does not emit gamma rays, and its radiation has a relatively small depth of penetration in the matter and a relatively long half-life.

  2. Promethium used as a pacemaker. A luminous paint containing a phosphor that absorbs the beta radiation emitted by promethium-147 and emits light is used by some signal lights.

  3. In atomic batteries, by sandwiching a small promethium source between two semiconductor plates, the beta particles emitted by promethium-147 are converted into electric current. These batteries have a lifetime of approximately five years. Promethium is often used to measure the thickness of materials by measuring the amount of radiation from a promethium source that passes through the sample. Potential applications can be made for portable X-ray sources and as auxiliary heat or power sources for space probes and satellites.


  • The promethium does not have a biological function. During its beta decay, Promethium-147 will emit gamma rays that are harmful to all life forms.  encounters with small amounts of promethium-147 are not dangerous If certain precautions are taken. In general, gloves, footwear covers, safety glasses, and an outer layer of protective clothing that can be quickly removed should be used.

  • Promethium mainly affects bone tissue. It is not risky to have a sealed promethium-147. If the packaging is impaired, however, then promethium becomes harmful for the environment and humans. The polluted area should be cleaned with water and soap if radioactive contamination is detected.

Did You Know?

There in the Andromeda galaxy is the peculiar star HR 465, which contains a lot of Promethium. It is very radioactive and rare, very little has been studied: it is not well described in its chemical and physical properties.

FAQs on Promethium

1. Is promethium made by man?

It is not found naturally on Earth. A star in the Andromeda galaxy has been found to produce promethium, although it is not known how. Promethium can be made by irradiating neutrons, deuterons, and alpha particles with neodymium and praseodymium.

2. Where is promethium found?

No, detectable quantities of promethium have been found in the earth's crust. As a result of uranium decay, it is present in minuscule quantities in uranium minerals. As a result of uranium fission, promethium may be manufactured. Isotopes: Promethium has 29 that are considered to have half-lives, with mass numbers ranging from 130 to 158.

3. Is promethium the strongest metal?

As a power source, volatile promethium is used as it can consume and produce electricity. We can say that  promethium is "man's strongest metal." (Tungsten is known to be the strongest natural metal in real life, steel is the strongest alloy, and chromium is the hardest metal.)