Caesium, 00Cs
Some pale gold metal, with a liquid-like texture and lustre, sealed in a glass ampoule
Caesium
Pronunciation/ˈsziəm/ (SEE-zee-əm)
Alternative namecesium (US)
Appearancepale gold
Standard atomic weight Ar°(Cs)
Caesium in the periodic table
Hydrogen Helium
Lithium Beryllium Boron Carbon Nitrogen Oxygen Fluorine Neon
Sodium Magnesium Aluminium Silicon Phosphorus Sulfur Chlorine Argon
Potassium Calcium Scandium Titanium Vanadium Chromium Manganese Iron Cobalt Nickel Copper Zinc Gallium Germanium Arsenic Selenium Bromine Krypton
Rubidium Strontium Yttrium Zirconium Niobium Molybdenum Technetium Ruthenium Rhodium Palladium Silver Cadmium Indium Tin Antimony Tellurium Iodine Xenon
Caesium Barium Lanthanum Cerium Praseodymium Neodymium Promethium Samarium Europium Gadolinium Terbium Dysprosium Holmium Erbium Thulium Ytterbium Lutetium Hafnium Tantalum Tungsten Rhenium Osmium Iridium Platinum Gold Mercury (element) Thallium Lead Bismuth Polonium Astatine Radon
Francium Radium Actinium Thorium Protactinium Uranium Neptunium Plutonium Americium Curium Berkelium Californium Einsteinium Fermium Mendelevium Nobelium Lawrencium Rutherfordium Dubnium Seaborgium Bohrium Hassium Meitnerium Darmstadtium Roentgenium Copernicium Nihonium Flerovium Moscovium Livermorium Tennessine Oganesson
Rb

Cs

Fr
xenoncaesiumbarium
Groupgroup 1: hydrogen and alkali metals
Periodperiod 6
Block  s-block
Electron configuration[Xe] 6s1
Electrons per shell2, 8, 18, 18, 8, 1
Physical properties
Phase at STPsolid
Melting point301.7 K ​(28.5 °C, ​83.3 °F)
Boiling point944 K ​(671 °C, ​1240 °F)
Density (near r.t.)1.93 g/cm3
when liquid (at m.p.)1.843 g/cm3
Critical point1938 K, 9.4 MPa[3]
Heat of fusion2.09 kJ/mol
Heat of vaporization63.9 kJ/mol
Molar heat capacity32.210 J/(mol·K)
Vapor pressure
P (Pa) 1 10 100 1 k 10 k 100 k
at T (K) 418 469 534 623 750 940
Atomic properties
Oxidation statescommon: +1
−1[4]
ElectronegativityPauling scale: 0.79
Ionization energies
  • 1st: 375.7 kJ/mol
  • 2nd: 2234.3 kJ/mol
  • 3rd: 3400 kJ/mol
Atomic radiusempirical: 265 pm
Covalent radius244±11 pm
Van der Waals radius343 pm
Color lines in a spectral range
Spectral lines of caesium
Other properties
Natural occurrenceprimordial
Crystal structurebody-centered cubic (bcc)
Bodycentredcubic crystal structure for caesium
Thermal expansion97 µm/(m⋅K) (at 25 °C)
Thermal conductivity35.9 W/(m⋅K)
Electrical resistivity205 nΩ⋅m (at 20 °C)
Magnetic orderingparamagnetic[5]
Young's modulus1.7 GPa
Bulk modulus1.6 GPa
Mohs hardness0.2
Brinell hardness0.14 MPa
CAS Number7440-46-2
History
Discovery1860
First isolationCarl Setterberg (1882)
Isotopes of caesium
Main isotopes[6] Decay
abun­dance half-life (t1/2) mode pro­duct
131Cs synth 9.7 d ε 131Xe
133Cs 100% stable
134Cs synth 2.0648 y ε 134Xe
β 134Ba
135Cs trace 1.33×106 y β 135Ba
137Cs synth 30.17 y[7] β 137Ba
 Category: Caesium
| references
Cs · Caesium
Xe ←

ibox Xe

iso
55
Cs  [e]
IB-Cs [e]
IBisos [e]
→ Ba

ibox Ba

indexes by PT (page)
child table, as reused in {IB-Cs}
Main isotopes of caesium
Main isotopes[6] Decay
abun­dance half-life (t1/2) mode pro­duct
131Cs synth 9.7 d ε 131Xe
133Cs 100% stable
134Cs synth 2.0648 y ε 134Xe
β 134Ba
135Cs trace 1.33×106 y β 135Ba
137Cs synth 30.17 y[7] β 137Ba
Data sets read by {{Infobox element}}
Name and identifiers
Symbol etymology (11 non-trivial)
Top image (caption, alt)
Pronunciation
Allotropes (overview)
Group (overview)
Period (overview)
Block (overview)
Natural occurrence
Phase at STP
Oxidation states
Spectral lines image
Electron configuration (cmt, ref)
Isotopes
Standard atomic weight
  most stable isotope
Wikidata
Wikidata *
* Not used in {{Infobox element}} (2023-01-01)
See also {{Index of data sets}} · Cat:data sets (46) · (this table: )

References

  1. ^ "Standard Atomic Weights: Caesium". CIAAW. 2013.
  2. ^ Prohaska, Thomas; Irrgeher, Johanna; Benefield, Jacqueline; Böhlke, John K.; Chesson, Lesley A.; Coplen, Tyler B.; Ding, Tiping; Dunn, Philip J. H.; Gröning, Manfred; Holden, Norman E.; Meijer, Harro A. J. (2022-05-04). "Standard atomic weights of the elements 2021 (IUPAC Technical Report)". Pure and Applied Chemistry. doi:10.1515/pac-2019-0603. ISSN 1365-3075.
  3. ^ Haynes, William M., ed. (2011). CRC Handbook of Chemistry and Physics (92nd ed.). Boca Raton, FL: CRC Press. p. 4.121. ISBN 1-4398-5511-0.
  4. ^ Dye, J. L. (1979). "Compounds of Alkali Metal Anions". Angewandte Chemie International Edition. 18 (8): 587–598. doi:10.1002/anie.197905871.
  5. ^ "Magnetic susceptibility of the elements and inorganic compounds". Handbook of Chemistry and Physics (PDF) (87th ed.). CRC press. ISBN 0-8493-0487-3. Retrieved 2010-09-26.
  6. ^ a b Kondev, F. G.; Wang, M.; Huang, W. J.; Naimi, S.; Audi, G. (2021). "The NUBASE2020 evaluation of nuclear properties" (PDF). Chinese Physics C. 45 (3): 030001. doi:10.1088/1674-1137/abddae.
  7. ^ a b "NIST Radionuclide Half-Life Measurements". NIST. Retrieved 2011-03-13.