What is the 137th element


Cesium-137 - radiocesium, symbol: 137Cs - is a radioactive isotope of cesium (see: Cesium isotopes) and arises exclusively anthropogenic as a fission product during nuclear fission in nuclear power plants and during nuclear explosions.

With a half-life of 30.17 years, cesium-137 decomposes to 94.6% under beta radiation into barium-137m, which in turn breaks down into the stable barium isotope with a half-life of 2.55 minutes 137Ba radiates and is responsible for sending out gamma rays; the rest of the cesium-137 decays directly to 137Ba. One gram of Cesium-137 has an activity of 3.215 TBq (Terabecquerel).

The cesium isotope 137 is actively used as a source of gamma rays, for example in cancer therapy, in materials testing and as a reference radiation source (test source).


Biological effect

Natural cesium (Cs-133) has little toxic effect on the organism in its salts and, like the similar alkali metal potassium, is absorbed in the gastrointestinal tract and stored in the tissue.

The uptake of cesium becomes problematic if the food is contaminated with anthropogenically produced cesium-137, for example after the Chernobyl event in 1986. The radiating Cs atoms - like K and normal Cs - are stored in the muscle tissue and are irradiated there the surrounding tissue. The biological half-life, which is 110 days, makes things even more difficult. H. during this period only half of the Cs atoms taken up were excreted again.


Environmental aspects

Naturally non-occurring cesium isotopes (134Cs, 134Cs) in small amounts, in nuclear weapon tests and in reactor accidents (Chernobyl 1986, Fukushima 2011) occasionally also in larger amounts into the environment, where they are responsible for the radioactive pollution of the environment over a longer period of time.

Cesium-137 is water-soluble in the form of its salts and is chemically related to the elements potassium and rubidium. After the cesium is absorbed by fungi and plants, the radioactive isotope enters the food chains of humans and animals. For details of the effects, see [2, 3].


additional Information

[1] - Properties of radiocesium and potassium-40.
Online information, environmental studies.

[2] - Cesium-free: Wild truffles are not radioactively contaminated.
Internet chemistry news, (2016).


Category: Chemical elements

Updated on February 02, 2020.

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