Look who discovered caesium...

Flame test for caesium

Source: © E.R. degginger/science photo library

Although Robert Bunsen and Gustav Kirchhoff are often credited with the discovery of caesium, this honour belongs to Carl Setterberg

Scientists should know not to trust everything they read on the Internet. An entry on caesium taken from a web-page ambitiously titled Chemistry explained  reads: 

Caesium was discovered in 1861 by German chemists Robert Bunsen (1811-99) and Gustav Kirchhoff 

(1824-87). They found the element using a method of analysis they had just invented: spectroscopy. Spectroscopy is the process of analysing light produced when an element is heated. The light produced is different for every element. The spectrum (plural: spectra) of an element consists of a series of coloured lines.   

 

Flame test for caesium

First, the authors get the date wrong. Caesium dates from 1860, making this year its 150th anniversary. Secondly, Kirchhoff was a physicist, not a chemist. Thirdly, to claim that he and Bunsen invented spectroscopy as a method of analysis is open to dispute. And spectroscopy involves flame-induced excitations and decays, the energies of which determine the colour of the flames.  

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