Showing results for "caesium"

• a variation of cesium.

caesium

British  

/ ˈsiːzɪəm /

noun

1. a ductile silvery-white element of the alkali metal group that is the most electropositive metal. It occurs in pollucite and lepidolite and is used in photocells. The radioisotope caesium-137 , with a half-life of 30.2 years, is used in radiotherapy. Symbol: Cs; atomic no: 55; atomic wt: 132.90543; valency: 1; relative density: 1.873; melting pt: 28.39±0.01°C; boiling pt: 671°C

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Example Sentences

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caesium

In 1955, the NPL invented the first atomic clock of the sort that is used today, based on the frequency of radiation from an atom of the element caesium.

From BBC ● Mar. 2, 2025

Within the sensors, the light passes through a small glass container containing a caesium gas, which absorbs the light at the right light frequencies.

From Science Daily ● May 2, 2024

The caesium 137 ceramic source, commonly used in radiation gauges, emits dangerous amounts of radiation, equivalent of receiving 10 X-rays in an hour.

From Seattle Times ● Jan. 29, 2023

The radioactive strontium, caesium and plutonium mainly affected Ukraine and neighboring Belarus, as well as parts of Russia and Europe.

From Reuters ● Feb. 25, 2022

We see, also, that caesium causes inflection, and rubidium does not; and these two metals are allied to sodium and potassium.

From Insectivorous Plants by Charles Darwin

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