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Robert Wilhelm Eberhard Bunsen (German:; 30 March 1811 [a] – 16 August 1899) was a German chemist.He investigated emission spectra of heated elements, and discovered caesium (in 1860) and rubidium (in 1861) with the physicist Gustav Kirchhoff. [11]
In vacuum applications, caesium dichromate can be reacted with zirconium to produce pure caesium metal without other gaseous products. [73] Cs 2 Cr 2 O 7 + 2 Zr → 2 Cs + 2 ZrO 2 + Cr 2 O 3. The price of 99.8% pure caesium (metal basis) in 2009 was about $10 per gram ($280/oz), but the compounds are significantly cheaper. [69]
The pure metal was eventually isolated in 1882 by Setterberg. [131] 37 Rubidium: 1861 R. Bunsen and G. R. Kirchhoff: 1863 R. Bunsen Bunsen and Kirchhoff discovered it just a few months after caesium, by observing new spectral lines in the mineral lepidolite. [132] The metal was isolated by Bunsen around 1863. [52] 81 Thallium: 1861 W. Crookes ...
All of the discovered alkali metals occur in nature as their compounds: in order of abundance, sodium is the most abundant, followed by potassium, lithium, rubidium, caesium, and finally francium, which is very rare due to its extremely high radioactivity; francium occurs only in minute traces in nature as an intermediate step in some obscure ...
Francium was discovered by Marguerite Perey [4] in France (from which the element takes its name) on January 7, 1939. [5] Before its discovery, francium was referred to as eka-caesium or ekacaesium because of its conjectured existence below caesium in the periodic table. It was the last element first discovered in nature, rather than by synthesis.
Delocalization in caesium is so strong that the electrons are virtually freed from the caesium atoms to form a gas constrained only by the surface of the metal. For caesium, therefore, the picture of Cs + ions held together by a negatively charged electron gas is very close to accurate (though not perfectly so).
Caesium (Cs) 55 caesius: Latin "blue-gray" [43] or "sky blue" descriptive (colour) From Latin caesius, which means "sky blue". Its identification was based upon the bright-blue lines in its spectrum, and it was the first element discovered by spectrum analysis. Barium (Ba) 56 βαρύς (barys) Greek via Neo-Latin "heavy" βαρύς (barys ...
It is a very soft, whitish-grey solid in the alkali metal group, similar to potassium and caesium. [9] Rubidium is the first alkali metal in the group to have a density higher than water . On Earth, natural rubidium comprises two isotopes : 72% is a stable isotope 85 Rb, and 28% is slightly radioactive 87 Rb, with a half-life of 48.8 billion ...