{"id":32,"date":"2020-04-08T14:57:19","date_gmt":"2020-04-08T14:57:19","guid":{"rendered":"https:\/\/thechemicalelements.com\/?page_id=32"},"modified":"2023-08-16T10:54:55","modified_gmt":"2023-08-16T10:54:55","slug":"caesium","status":"publish","type":"post","link":"https:\/\/thechemicalelements.com\/caesium\/","title":{"rendered":"Caesium (Cs) (Cesium)"},"content":{"rendered":"\n

Caesium is a chemical element with an atomic number of 55 in the periodic table of elements. It\u2019s the 45th most abundant element in Earth\u2019s crust. Being a member of the alkali metals family of periodic table elements<\/a>, caesium has been classified as one of the <\/span>incompatible elements<\/span><\/i>. <\/span><\/p>\n\n\n\n

Caesium has eight valence electrons that make this element the most reactive metal of all the other alkali metals.\u00a0<\/span><\/p>\n\n\n\n

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Chemical and Physical Properties of Caesium<\/span><\/h3>\n\n\n\n
Property<\/strong><\/td>Value<\/strong><\/td><\/tr>
Symbol of Cesium<\/td>Cs<\/td><\/tr>
Name<\/td>Cesium<\/td><\/tr>
Atomic Number<\/td>55<\/td><\/tr>
Atomic Mass<\/td>132.90543<\/td><\/tr>
Uses<\/td>Used as a ‘getter’ to remove air traces in vacuum and cathode-ray tubes. Also used in producing photoelectric devices and atomic clocks. Since it ionizes readily, it is used as an ion rocket motor propellant.<\/td><\/tr>
Description<\/td>Soft, slightly malleable, silvery-white metal.<\/td><\/tr>
Group<\/td>1 (Alkali Metals<\/a>)<\/td><\/tr>
Shells<\/td>2,8,18,18,8,1<\/td><\/tr>
Orbitals<\/td>[Xe] 6s1<\/td><\/tr>
Valence<\/td>1<\/td><\/tr>
Crystal Structure<\/td>Cubic: Body centered<\/td><\/tr>
Electronegativity<\/td>0.79<\/td><\/tr>
Covalent Radius<\/td>2.35 \u00c5<\/td><\/tr>
Atomic Radius<\/td>3.34 \u00c5<\/td><\/tr>
Atomic Volume<\/td>71.07 cm\u00b3\/mol<\/td><\/tr>
Name Origin<\/td>Latin: coesius (sky blue); for the blue lines of its spectrum.<\/td><\/tr>
Discovered By<\/td>Gustov Kirchoff, Robert Bunsen<\/td><\/tr>
Year<\/td>1860<\/td><\/tr>
Location<\/td>Germany<\/td><\/tr>
Pronounced<\/td>SEE-zi-em<\/td><\/tr>
Oxidation States<\/td>1<\/td><\/tr>
Density<\/td>1.873 g\/cm\u00b3<\/td><\/tr>
Melting Point<\/td>28.5 \u00b0C (83.3 \u00b0F)<\/td><\/tr>
Boiling Point<\/td>669 \u00b0C<\/td><\/tr>
Color<\/td>Silvery-golden alkali metal<\/td><\/tr>
Physical State<\/td>Liquid at or near room temperature<\/td><\/tr>
Half-life<\/td>From 500(100) \u00b5s to 2.3 million years<\/td><\/tr>
Van der Waals Radius<\/td>0.267 nm<\/td><\/tr>
Ionic Radius<\/td>1.74 (+1) \u00c5<\/td><\/tr>
Isotopes<\/td>40<\/td><\/tr>
Most Characteristic Isotope<\/td>133Cs, 137Cs<\/td><\/tr>
The Energy of the First Ionization<\/td>375.6 kJ.mol-1<\/td><\/tr>
Discovery Date<\/td>In 1860 by Robert Bunsen, Gustav Kirchhoff, and Carl Setterberg<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n

Caesium has the periodic table symbol Cs, atomic number 55, and an atomic mass of 132.9054 g.mol<\/span> -1<\/span>. The ground state electronic configuration of neutral caesium is [Xe] 6s<\/span>1<\/span>. <\/span><\/p>\n\n\n\n

Caesium is a soft and ductile metal in a liquid aggregate state at room temperature. It reaches its boiling point at 669 \u00b0C, while the melting point of caesium is achieved at 28.5 \u00b0C (83.3 \u00b0F). This member of the alkali metals family of elements has an electronegativity of 0.79 according to Pauling which makes it the least electronegative chemical element of the periodic table. The atomic radius of caesium according to van der Waals is 0.267 nm. It\u2019s the most alkaline element of the periodic table. <\/span><\/p>\n\n\n\n

Both the physical and the chemical properties of caesium resemble those of rubidium <\/a>and potassium<\/a>. The crystal structure of caesium is a body-centered cubic, resembling two interpenetrating simple cubic lattices. <\/span><\/p>\n\n\n\n

This alkali metal is pyrophoric by nature, i.e. it spontaneously ignites after being exposed to air for only 5 minutes. In contact with cold water, caesium creates volatile, explosive reactions due to the formation of hydrogen <\/a>gas and a solution of caesium ions and hydroxide ions:<\/span><\/p>\n\n\n\n

2Cs (s) + 2H\u2082O (l) \u2192 H\u2082 (g) + 2Cs\u207a (aq) + 2OH\u207b (<\/span>aq) <\/span>                       <\/span><\/p>\n\n\n\n

The most volatile caesium reactions occur in the presence of fluorine<\/a>, chlorine<\/a>, bromine<\/a>, and iodine<\/a>, while sulfur<\/a> and phosphorus<\/a> trigger its incandescence (emission of light) after exposure to high temperatures. <\/span><\/p>\n\n\n\n

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How Was Caesium Discovered?<\/span><\/h2>\n\n\n\n

The story of this chemical element begins in 1846 when the German metallurgical chemist and a son of a miner, Karl Friedrich Plattner (1800 – 1858), conducted research on the mineral pollucite (caesium aluminum silicate). <\/span><\/p>\n\n\n\n

Despite having an ore containing a chemical element that was waiting to be discovered, Plattner could not provide scientific proof for 7% of the elements that made up the mineral in his hands. Unfortunately, he also mistakenly thought that caesium is, in fact, a sodium <\/a>and potassium compound.\u00a0<\/span><\/p>\n\n\n\n

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Robert Bunsen and Gustav Kirchhoff<\/span><\/h3>\n\n\n\n

In 1860, the two German scientists Robert Bunsen and Gustav Kirchhoff applied the new spectroscopic method in their scientific research for the first time. By attempting an experiment on the spectral emissions of a mineral water sample rich in lithium <\/a>compounds, the chemist and the physicist teamed up and observed the newly occurring sky-blue lines in the spectrum which were incomparable to any known chemical element. This gave them a sign that they are on the way to the discovery of a new chemical element, the caesium. <\/span><\/p>\n\n\n\n

In their further experimental attempts, Bunsen and Kirchoff managed to produce approximately 7 grams of caesium chloride, but never succeeded in isolating the pure elemental form of the new alkali metal. Whatever technique they applied, the result was always a type of blue molten mass.<\/span><\/p>\n\n\n\n

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Carl Theodor Setterberg<\/span><\/h3>\n\n\n\n

Twenty years later, the Swedish chemist Carl Theodor Setterberg (1853 – 1941) was the scientist who, in the end, earned the credits for the discovery of caesium. Namely, by conducting electrolysis of molten caesium cyanide (CsCN) at the University of Bonn, Setterberg succeeded in isolating the pure elemental form of caesium. <\/span><\/p>\n\n\n\n

First, he extracted lithium from lepidolite ore, Setterberg added a mixture of cesium-based salts to the chemical. This reaction led him to the first isolated quantity of caesium.\u00a0\u00a0<\/span><\/p>\n\n\n\n

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The Revolutionary Invention of the Spectroscopy<\/span><\/h3>\n\n\n\n

The year was 1822. John Herschel heated a compound in one of his chemical attempts, and among the different colors of flame that passed through the prism, Herschel also observed unseen lines of the spectrum. This prismatic spectrum of a flame was a point of interest for this English polymath (mathematician, astronomer, chemist, experimental photographer, and inventor of the blueprint). <\/span><\/p>\n\n\n\n

Herschel believed that this occurrence is due to the existence of substances that must be analyzed with a more powerful technique and equipment needed to measure the interactions between light and matter, rather than the usual technique of electrolysis.<\/span><\/p>\n\n\n\n

Fast forward to 1989, Robert Bunsen entertained the idea of using filters to block the intense colors emitted by the substances (such as chromium<\/a> yellow) so that the less intensive colors (potassium\u2019s ultraviolet, for instance) could be more easily detected. For this, he came up with the idea for spectroscopy – the technique he used to identify the chemical substances that emit light under applied heat. <\/span><\/p>\n\n\n\n

Despite the failure to introduce a new chemical to the world, Bunsen and Kirchoff received the Davy Medal for their scientific efforts and discoveries in the realm of spectrum analysis.\u00a0<\/span><\/p>\n\n\n\n

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How Did Caesium Get Its Name?<\/span><\/h2>\n\n\n\n

The Latin word <\/span>caesius,<\/span><\/i> meaning \u2018heavenly blue\u2019, was used to name the element caesium (also spelled cesium in American English) as a result of the unique sky-blue lines it emits.\u00a0<\/span><\/p>\n\n\n\n

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Where Can You Find Caesium?<\/span><\/h2>\n\n\n\n

The minerals <\/span>pollucite<\/span><\/i> (CsAlSi<\/span>2<\/span>O<\/span>6 <\/span>) and <\/span>lepidolite<\/span><\/i> (K(Li,Al)\u2083(Al,Si,Rb)\u2084O\u2081\u2080(F,OH)\u2082) are the main sources of caesium. In nature, caesium often occurs along with rubidium and other alkali metals. Ores of these minerals can be found on locations in Bernic Lake, Manitoba, Canada, Zimbabwe, South-West Africa, and in the United States. <\/span><\/p>\n\n\n\n

Caesium traces can be also found in the human body. The quantities of this trace element in the human body can be measured by analysis of blood, urine, and feces.<\/span><\/p>\n\n\n\n

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Caesium in Everyday Life<\/span><\/h2>\n\n\n\n

The Use of Caesium and the Atomic Clocks<\/span><\/h3>\n\n\n\n

One of the most widespread everyday uses of caesium is its application in <\/span>atomic clocks<\/span><\/i>.<\/span> Caesium is used in atomic clocks because of the vibration frequency of the caesium atom. The electron resonance frequency of the caesium atom is 9,192,631,770 cycles per second, which gives caesium clocks an incredible accuracy. Atomic clocks enable the function of GPS, cell phones, and the Internet.<\/span><\/p>\n\n\n\n

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The Use of Caesium in Mineral Water Production<\/span><\/h3>\n\n\n\n

Naturally occurring in springs of mineral water, caesium salts are also applied in the process of commercial production of mineral water. The caesium isotopes are also used for the purification of the water.<\/span><\/p>\n\n\n\n

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Other Uses of Caesium <\/span><\/h3>\n\n\n\n

This rare element is also used as one of the vital components in:<\/span><\/p>\n\n\n\n