Cesium (Cs) Elemental Symbol

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Césium Cesium Cesio Césio Cesio Cesium

Cesium(Cs) and molecular weight, atomic number and elemental symbolCesium (or Caesium ) is a Block S, Group 1, Period 6 element. The number of electrons in each of Cesium's shells is 2, 8, 18, 18, 8, 1 and its electronic configuration is [Xe] 6s1. The cesium atom has a radius of 265.5.pm and its Van der Waals radius is 200.pm. In its elemental form, CAS 7440-46-2, cesium has a silvery gold appearance. Cesium is a member of the alkali group of metals. It is one of three metals that occur as a liquid at room Cesium Bohr Model temperature - the others are mercury and gallium. Elemental CesiumCesium's main commercial source is pollucite ore; however, it is also found in beryl, avogadrite, pezzottaite, and londonite. Cesium was first discovered by Robert Bunsen and Gustav Kirchhoff in 1860. Cesium is named for the vibrant blue lines in its spectrum. The word Cesium originates from the Latin word caesius, meaning "sky blue". Cesium information, including technical data, safety data, high purity properties, research, applications and other useful facts are discussed below. Scientific facts such as the atomic structure, ionization energy, abundance on earth, conductivity and thermal properties are also included.

Cesium is used as an oxygen "getter" in vacuum and electronic tubes and as a component of photoelectric cells. Atomic clocks use the microwave spectral line emitted by Cesium Isotope 133 for reference. Radioactive Cesium 137 is an artificial isotope that is used for cancer radiotherapy. High Purity (99.999%) Cesium Oxide (Cs2O) PowderLaboratories use various cesium compounds for their ability to hydrogenate organic compounds. Cesium is available as metal and compounds with purities from 99% to 99.999% (ACS grade to ultra-high purity). Nanoparticles and nanopowders provide ultra-high surface area which nanotechnology research and recent experiments demonstrate function to create new and unique properties and benefits. Oxides are available in forms including powders and dense pellets for such uses as optical coating and thin film applications. Oxides tend to be insoluble. Fluorides are another insoluble form for uses in which oxygen is undesirable such as metallurgy, chemical and physical vapor deposition and in some optical coatings. Cesium is available in soluble forms including chlorides, nitrates and acetates. These compounds are also manufactured as solutions at specified stoichiometries.

Cesium compounds are slightly toxic. Safety data for Cesium and its compounds can vary widely depending on the form. For potential hazard information, toxicity, and road, sea and air transportation limitations, such as DOT Hazard Class, DOT Number, EU Number, NFPA Health rating and RTECS Class, please see the specific material or compound referenced in the Products tab below.

  • Properties
  • Safety Data
  • Products
  • Research
  • Isotopes
  • Other Elements

Cesium Properties

Symbol: Cs Melting Point: 301.59 K, 28.44 °C, 83.19 °F
Atomic Number: 55 Boiling Point: 944 K, 671 °C, 1240 °F
Atomic Weight: 132.9054519 Density: 1.93 g·cm−3
Element Category: alkali metal Liquid Density @ Melting Point: 1.843 g·cm−3
Group, Period, Block: 1 , 6, s Specific Heat: 0.24J/gK
    Heat of Vaporization 66.5 kJ mol-1
CHEMICAL STRUCTURE Heat of Fusion 2.09 kJ mol-1
Electrons: 55 Thermal Conductivity: 35.9 W·m−1·K−1
Protons: 55 Thermal Expansion: (25 °C) 97 µm·m−1·K−1
Neutrons: 78 Electrical Resistivity: (20 °C) 205 nΩ·m
Electron Configuration: [Xe 6s1 2, 8, 18, 18, 8, 1 Electronegativity: 0.79 (Pauling scale)
Atomic Radius: 265 pm Tensile Strength: N/A
Covalent Radius: 244±11 pm Molar Heat Capacity: 32.210 J·mol−1·K−1
Van der Waals radius: 343 pm Young's Modulus: 1.7 GPa
Oxidation States: 1 (strongly basic oxide) Shear Modulus: N/A
Phase: Solid Bulk Modulus: 1.6 GPa
Crystal Structure: body-centered cubic Poisson Ratio: N/A
Magnetic Ordering: paramagnetic Mohs Hardness: 0.2
1st Ionization Energy: 375.71 kJ mol-1 Vickers Hardness: N/A
2nd Ionization Energy: 2234.37 kJ mol-1 Brinell Hardness: 0.14 MPa
3rd Ionization Energy: 3rd: 3400 kJ·mol−1 Speed of Sound: N/A
CAS Number: 7440-46-2 Abundance in typical human body, by weight: 20 ppb
ChemSpider ID: 4510778 Abundance in typical human body, by atom: 1 ppb
PubChem CID: 5354618 Abundance in universe, by weight: 0.8 ppb
MDL Number: MFCD00134037 Abundance in universe, by atom: 0.1 ppb
EC Number: 231-155-4 Discovered By: Robert Bunsen and Gustav Kirchhoff
Beilstein Number: N/A Discovery Date: 1860
SMILES Identifier: [Cs]  
InChI Identifier: InChI=1S/Cs Other Names: Caesium

Health, Safety & Transportation Information for Cesium

Material Safety Data Sheet MSDS
Signal Word Danger
Hazard Statements H260-H314
Hazard Codes F,C
Risk Codes 11-14/15-34
Safety Precautions 8-16-26-36/37/39-43-45
RTECS Number FK9225000
Transport Information UN 1415 4.3/PG 1
WGK Germany 3
Globally Harmonized System of
Classification and Labelling (GHS)
Corrosion-Corrosive to metals Flame-Flammables  

Recent Research & Development for Cesium

  • Adsorptive removal of cesium using bio fuel extraction microalgal waste. Inoue K, Gurung M, Adhikari BB, Alam S, Kawakita H, Ohto K, Kurata M, Atsumi K. J Hazard Mater. 2014.
  • Selective removal of cesium from aqueous solutions with nickel (II) hexacyanoferrate (III) functionalized agricultural residue-walnut shell. Ding D, Lei Z, Yang Y, Feng C, Zhang Z. J Hazard Mater. 2014.
  • Electrochemical assessment of water|ionic liquid biphasic systems towards cesium extraction from nuclear waste. Stockmann TJ, Zhang J, Montgomery AM, Ding Z. Anal Chim Acta. 2014.
  • Oxonium Ions Substituting Cesium Ions in the Structure of the New High-Pressure Borate HP-Cs1-x (H3 O)x B3 O5 (x=0.5-0.7). Sohr G, Neumair SC, Heymann G, Wurst K, Schmedt Auf der Günne J, Huppertz H. Chemistry. 2014.
  • Cesium and strontium in Black Sea macroalgae. Nonova T, Tosheva Z. J Environ Radioact. 2014.
  • Cesium accumulation of Rhodococcus erythropolis CS98 strain immobilized in hydrogel matrices. Takei T, Yamasaki M, Yoshida M. J Biosci Bioeng. 2014.
  • Versatile reactivity of Pd-catalysts: mechanistic features of the mono-N-protected amino acid ligand and cesium-halide base in Pd-catalyzed C-H bond functionalization. Musaev DG, Figg TM, Kaledin AL. Chem Soc Rev. 2014.
  • Structural, mechanical and electronic properties of 3d transition metal nitrides in cubic zincblende, rocksalt and cesium chloride structures: a first-principles investigation. Liu ZT, Zhou X, Khare SV, Gall D. J Phys Condens Matter. 2014 Jan.
  • Biosorption behavior and mechanism of cesium-137 on Rhodosporidium fluviale strain UA2 isolated from cesium solution. Lan T, Feng Y, Liao J, Li X, Ding C, Zhang D, Yang J, Zeng J, Yang Y, Tang J, Liu N. J Environ Radioact. 2014.
  • Influence of the cavity size of water-soluble cryptophanes on their binding properties for cesium and thallium cations. Brotin T, Goncalves S, Berthault P, Cavagnat D, Buffeteau T. J Phys Chem B.
  • A New Cesium Pentaborate with New B10O19 Building Blocks. Jiao A, Yu H, Wu H, Pan S, Zhang X. Inorg Chem. 2014
  • Synthesis and characterization of novel macroporous silica-polymer-calixcrown hybrid supramolecular recognition materials for effective separation of cesium. Xiao C, Zhang A, Chai Z. J Hazard Mater. 2014.
  • [Biochemical changes in rats under the influence of cesium chloride]. Mel'nykova NM, Iermishev OV. Ukr Biokhim Zh. 2013.
  • Global searches for microalgae and aquatic plants that can eliminate radioactive cesium, iodine and strontium from the radio-polluted aquatic environment: a bioremediation strategy. Fukuda SY, Iwamoto K, Atsumi M, Yokoyama A, Nakayama T, Ishida KI, Inouye I, Shiraiwa Y. J Plant Res. 2013 Dec.
  • The effect of fertilization on cesium concentration of rice grown in a paddy field in Fukushima Prefecture in 2011 and 2012. Ohmori Y, Kajikawa M, Nishida S, Tanaka N, Kobayashi NI, Tanoi K, Furukawa J, Fujiwara T. J Plant Res. 2013 Dec.
  • Effects of accompanying anions on cesium retention and translocation via droplets on soybean leaves. J Environ Radioact. 2013 create date:2013/09/26 | first author:Yan D
  • Enhancement of laser desorption ionization mass spectrometric signals of cesium iodide by elemental sulfur. Kruegel A, Pavlov J, Attygalle AB. Rapid Commun Mass Spectrom. 2013.
  • Difference in cesium accumulation among rice cultivars grown in the paddy field in Fukushima Prefecture in 2011 and 2012. Ohmori Y, Inui Y, Kajikawa M, Nakata A, Sotta N, Kasai K, Uraguchi S, Tanaka N, Nishida S, Hasegawa T, Sakamoto T, Kawara Y, Aizawa K, Fujita H, Li K, Sawaki N, Oda K, Futagoishi R, Tsusaka T, Takahashi S, Takano J, Wakuta S, Yoshinari A, Uehara M, Takada S, Nagano H, Miwa K, Aibara I, Ojima T, Ebana K, Ishikawa S, Sueyoshi K, Hasegawa H, Mimura T, Mimura M, Kobayashi NI, Furukawa J, Kobayashi D, Okouchi T, Tanoi K, Fujiwara T. J Plant Res. 2013 Dec.
  • The transfer of radioactive cesium and potassium from rice to sake. Okuda M, Hashiguchi T, Joyo M, Tsukamoto K, Endo M, Matsumaru K, Goto-Yamamoto N, Yamaoka H, Suzuki K, Shimoi H. J Biosci Bioeng. 2013.
  • Sensitive and selective detection of cesium via fluorescence quenching. Radaram B, Mako T, Levine M. Dalton Trans.

Cesium Isotopes

Caesium (Cs) has 40 known isotopes with atomic masses ranging from 112 to 151. 133Cs is the only stable isotope.

Nuclide Symbol Isotopic Mass Half-Life Nuclear Spin
133Cs 132.905451933 Stable 7/2+