Periodic Table -> Promethium

Promethium


Promethium Details

Promethium Symbol: Pm

Promethium Atomic Number: 61

Promethium Atomic Weight: 144.91

What is Promethium?

Promethium (atomic number 61, symbol Pm) is a metal that rarely occurs in nature. It is an artificially produced and radioactive element and earth metal. It can be obtained from fission products of other elements, including plutonium, thorium, and uranium. The element is found in very small amounts in the composition of uranium ores. Astronomers have observed promethium in the spectra of stars that belong to the Andromeda galaxy.

This element is paramagnetic and has 9 isotopes and hexagonal crystal structure. Its electronegativity according to Pauling, ionic radius, and Van Der Waals radius are unknown. The metal is in solid state at room temperature, and its boiling point is 2460 C. The chemical properties of promethium are little studied because it is radioactive. It is thought to behave similarly to other rare-earths such as cerium, scandium, europium, and neodymium. Its hydration energy and melting point are lower than samarium but higher than neodymium. Over 30 compounds of promethium have been created so far, including binary compounds with hydrogen, oxygen, and halogens. Promethium salts have a greenish or pale blue glow.

The element has no stable isotopes and its nuclear isomers are 18 in total. Promethium-151 has a half-life of 1.18 days while promethium-148 has a half-life of about 43 days. The only isotope that has commercial application is promethium-147. All isotopes of the element are radioactive meaning that they have unstable nuclei and release radiation spontaneously. All elements from the periodic table have at least one radioactive isotope. However, there are only two elements with an atomic number below 83 promethium and technetium that have radioactive isotopes only. The element itself does not have a stable state.

Promethium-147 is used in atomic batteries. The element can be used as a power source because it releases energy. Promethium-based batteries are an alternative to other battery types which are too large or heavy. They are an effective energy source on space probs and satellites but are very expensive for everyday use. Batteries of this kind are expected to provide power for up to 5 years. Other possible applications of promethium are in the manufacturing of batteries for pacemakers, watches, and missiles.


Promethium was discovered by the US chemist Jacob Marinsky in 1945. Lawrence Glendenin and Jacob Marinsky used neutrons to bombard neodymium and produced promethium. They were also successful in extracting the metal from fission products. It was only in 1963 that a sample of promethium was produced. Today, scientists use particle accelerators to artificially isolate the element. Spectroscopes have been used to detect the presence of promethium and its isotopes.

The element has no biological role. Its oceanic and crustal abundance are unknown. Given that promethium is a rare metal, it poses no threat to animal and plant life. Laboratory tests have shown that the metal accumulates on the surface of bones. It takes time to be released from the body. Promethium is very radioactive and should be handled with care. Protective clothing, safety glasses, and gloves should be worn. All compounds of promethium are highly toxic, and metal dust should be handled with care. It presents an explosion and fire hazard.

Promethium was originally present on earth but is now found in trace amounts. It disappeared because of radioactive decay. The element is only handled in nuclear facilities and research laboratories.



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