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


Name Rubidium Symbol Rb
atomic number 37 Atomic weight 85.467
Density @ 293 K 1.53 g/cm3 Atomic volume 55.9 cm3/mol
Group Alkali Met. discovered 1861


state (s, l, g) s
melting point 312.09 K boiling point 961 K
Heat of fusion 2.192 kJ/mol Heat of vaporization 72.216 kJ/mol
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1st ionization energy 403 kJ/mole electronegativity 0.82
2nd ionization energy 2632.1 kJ/mole electron affinity 46.885 kJ/mole
3rd ionization energy 3859.4 kJ/mole Specific heat 0.363 J/gK
heat atomization 86 kJ/mole atoms

Oxidation & Electrons

Shells 2,8,18,8,1 electron configuration [Kr] 5s1
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 silvery-white
uses photocells toxicity
hardness 0.3 mohs characteristics soft


reaction with air vigorous, = RbO2 reaction with 6M HCl vigorous, = H2, RbCl
reaction with 6M HCl vigorous, = H2, RbCl reaction with 15M HNO3 vigorous,= RbNO3, H2, NOx
reaction with 6M NaOH vigorous, = H2, RbOH
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Other Forms

number of isotopes 2 hydride(s) RbH
oxide(s) Rb2O chloride(s) RbCl


ionic radius (2- ion) pm ionic radius (1- ion) pm
atomic radius 248 pm ionic radius (1+ ion) 166 pm
ionic radius (2+ ion) pm ionic radius (3+ ion) pm
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thermal conductivity 58.2 J/m-sec-deg electrical conductivity 77.9 1/mohm-cm
polarizability 47.3 A^3


source Li extractn by-product rel. abund. solar system 0.851 log
abundance earth's crust 2 log cost, pure 1200 $/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.