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Rubidium

Metalsolid
Symbol: Rb
Atomic number: 37
Atomic mass: 85.4678
Group: Alkali Metal
CAS-number: 7440-17-7

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Physical data
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Physical data

Electronic dataThermal dataSteric data
Shells: 2, 8, 18, 8, 1
Orbitals: [Kr] 5s1
Electronegativity: 0.8, 0.9
1. Ionization potential: 4.1771 eV
2. Ionization potential: 27.28 eV
3. Ionization potential: 40.0 eV
Oxidation states: 1
Electrical conductivity: 0.0779 10^6
Melting point: 38.89 °C
Boiling point: 686 °C
Specific heat: 0.363 J/gK
Heat of fusion: 2.192 kJ/mol
Heat of vaporization: 72.216 kJ/mol
Thermal conductivity: 0.582 W/cmK
Atomic radius: 2.98 Å
Ionic radius: 1.61 Å (+1)
Covalent radius: 2.16 Å
Atomic volume: 55.9 cm³/mol
Density (293 K): 1.53 g/cm³
Crystal structure: cubic body centered
cubic body centered

Isotopes

NuclideAbundance [%]MassSpinHalflifeDecay modeDecay tree
81Rb 0 81 3/2 4.57h EC, β+ View
82Rb 0 82 1 1.258m β+, EC View
83Rb 0 83 5/2 86.2d EC, EC View
84Rb 0 83.914 2 32.9d EC, β+, β- View
85Rb 72.15 84.9118 5/2 -- --
85Rbm 0 85 0 >1µs IT View
86Rb 0 85.911 2 18.65d β-, EC View
87Rb 27.85 86.9092 3/2 4.8E10y β- View
88Rb 0 88 2 17.7m β- View
89Rb 0 89 3/2 15.44m β- View
90Rb 0 90 1 2.6m β- View
90Rbm 0 90 4 4.3m β-, IT View

Other info

Name origin:Latin: rubidus (deep red); the color its salts impart to flames
Description:Soft, silvery-white, highly reactive metal.
Discovered by:R. Bunsen, G. Kirchoff
Year:1861
Place:Germany
Sources:Occurs abundantly, but so widespread that production is limited. Usually obtained from lithium production.
Use(s):Used as a catalyst, in photocells, and in vacuum and cathode-ray tubes.