![]() Bunsen suggested calling the element cesium, from the Latin word caesius for "sky blue." For many years, the name was also spelled caesium. These elements were already well known.Īfter Bunsen and Kirchhoff removed all these elements from their sample, they were surprised to find two beautiful blue lines in the spectrum of the "empty" spring water. ![]() They saw spectral lines for sodium, potassium, lithium, calcium, and strontium. In 1859, Bunsen and Kirchhoff were studying a sample of mineral water taken from a spring. Such was the case with the discovery of cesium. Using spectroscopy, a chemist can identify the elements by these distinctive lines. When the substance is heated, the hidden elements give off characteristic spectral lines. But the element is much easier to detect by spectroscopy. In many cases, the amount of an element present in a sample is too small to see. The invention of spectroscopy gave chemists a powerful new tool. One of its radioactive isotopes, cesium-137, is widely used in a variety of medical and industrial applications. The spectrum (plural: spectra) of an element consists of a series of colored lines.Ĭesium is not a common element, and it has few commercial uses. The light produced is different for every element. Spectroscopy is the process of analyzing light produced when an element is heated. They found the element using a method of analysis they had just invented: spectroscopy. Although in theory francium is more active than cesium, francium is too rare to have any commercial uses.Ĭesium was discovered in 1861 by German chemists Robert Bunsen (1811-99) and Gustav Kirchhoff (1824-87). Cesium is considered the most active metal. The alkalis include lithium, sodium, potassium, rubidium, and francium. The periodic table is a chart that shows how chemical elements are related to each other. OverviewĬesium is a member of the alkali family, which consists of elements in Group 1 (IA) of the periodic table. With a low melting point of around 28.4 ☌ it is liquid around room temperature like mercury and very fascinating to look at, but caesium possesses the property as one of the most reactive elements on the table.Note: This article, originally published in 1998, was updated in 2006 for the eBook edition. However very pure samples of caesium cause the gold colour to diminish as traces of oxygen supposedly gives it the colour. To finish off, caesium is also quite aesthetically pleasing as it is only one of three metallic elements that are not silver-coloured along with gold and copper. They give the standard measure of time: the electron resonance frequency of the caesium atom is 9,192,631,770 cycles per second. These clocks are a vital part of the Global Positioning System (GPS) satellites. Some of its uses are in radio vacuum tubes as a getter, photoelectric cells and catalysts in several organic reactions but one of its most notable uses is in the ‘caesium clock’ (atomic clock). Since its discovery in 1860, caesium has been used effectively in our everyday lives, some uses more valuable than others, yet some people are oblivious to caesium being more than just another element on the periodic table. The credit for discovering the pure metal goes to Carl Theodor Setterberg at the University of Bonn who obtained it by the electrolysis of molten caesium cyanide, CsCN. However, as they were unable to produce a sample of the pure metal itself, it would be wrong to only credit them for the discovery. After a few more steps, which can be read up on using the first reference below, the remaining caesium was separated using difference in solubility of its carbonate in alcohol and yielded 7.3 grams of caesium chloride. This was done by initially evaporating the mineral water to produce 240 kilograms of concentrated salt solution and precipitating the solution to leave the alkali metal. The process to obtain caesium was a lengthy one as 44,000 litres of mineral water was required to produce around only 7 grams of caesium chloride. This was because of the appearance of its emission spectrum in the spectroscope being of a blue colour. It was also the first element to be discovered using a spectroscope and was given the name caesium which was derived from the Latin word caesius, which means sky-blue. Unfortunately, as he ran out of material to analyse from he only accounted for 93% of the elements it contained.Įventually in 1860, Gustav Kirchhoff and Robert Bunsen discovered caesium in mineral water at Heidelberg using the spectroscope they had invented a year earlier. In 1846 caesium was almost discovered by Carl Plattner while investigating mineral pollucite which is caesium aluminium silicate.
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