General | States | Energies | Oxidation & Electrons |Appearance & Characteristics
Reactions | Other Forms |Radius | Conductivity | Abundance
Encyclopedia Britannica articles


Name Cesium Symbol Cs
atomic number 55 Atomic weight 132.9054
Density @ 293 K 1.873 g/cm3 Atomic volume 71.07 cm3/mol
Group Alkali Met. discovered 1860


state (s, l, g) s
melting point 301.6 K boiling point 978 K
Heat of fusion 2.092 kJ/mol Heat of vaporization 67.740 kJ/mol
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1st ionization energy 375.7 kJ/mole electronegativity 0.79
2nd ionization energy 2421.8 kJ/mole electron affinity 45.506 kJ/mole
3rd ionization energy kJ/mole Specific heat 0.24 J/gK
heat atomization 79 kJ/mole atoms

Oxidation & Electrons

Shells 2,8,18,18,8,1 electron configuration [Xe] 6s1
minimum oxidation number 0 maximum oxidation number 1
min. common oxidation no. 0 max. common oxidation no. 1
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Appearance & Characteristics

structure bcc: body-centered cubic color yellow/silvery
uses photocells, IR lamps toxicity
hardness 0.2 mohs characteristics softest metal


reaction with air vigorous, = CsO2 reaction with 6M HCl vigorous, = H2, CsCl
reaction with 6M HCl vigorous, = H2, CsCl reaction with 15M HNO3 vigorous, = CsNO3
reaction with 6M NaOH vigorous, = H2, CsOH
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Other Forms

number of isotopes 1 hydride(s) CsH
oxide(s) Cs2O chloride(s) CsCl


ionic radius (2- ion) pm ionic radius (1- ion) pm
atomic radius 265 pm ionic radius (1+ ion) 181 pm
ionic radius (2+ ion) pm ionic radius (3+ ion) pm
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thermal conductivity 35.9 J/m-sec-deg electrical conductivity 48.9 1/mohm-cm
polarizability 59.6 A^3


source Li extractn by-product rel. abund. solar system -0.429 log
abundance earth's crust 0 log cost, pure 1100 $/100g
cost, bulk $/100g
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World Wide Web presentation of Chemicool Periodic Table is © Copyright 1996-99 by David D. Hsu. Some data were provided by and used with the permission of JCE Software and is owned and copyright by the Division of Chemical Education, Inc. Additional data were provided by Perkin-Elmer through Peter Lykos of IIT. The information may not be redistributed without the permission of David Hsu or JCE Software.