Rubidium

Rubidium (Rb)

Soft silvery metallic element, belongs to group 1 of the periodic table. Rb-97, the naturally occurring isotope, is radioactive. It is highly reactive, with properties similar to other elements in group 1, like igniting spontaneously in air. Discovered spectroscopically in 1861 by W. Bunsen and G.R. Kirchoff.
Atomic Number37
Atomic Weight85.4678
Mass Number85
Group1
Period5
Blocks
Protons37 p+
Neutrons48 n0
Electrons37 e-
RbMetal.JPG Animated Bohr Model Enhanced Bohr Model Bohr Model Orbital Diagram

Properties

Atomic Radius
235 pm
Atomic Volume
Covalent Radius
210 pm
Metallic Radius
216 pm
Ionic Radius
152 pm
Crystal Radius
166 pm
Van der Waals radius
303 pm
Density
1.53 g/cm³
Boiling Point
961 K
Melting Point
312.2 K
Electrons per shell2, 8, 18, 8, 1
Electronegativity
0.82
Electrophilicity
0.7363448717298 eV/particle
Proton Affinity
Electron Affinity
0.48592 eV/particle
Ionization Potential
4.177128 eV/particle
Heat of Vaporization
75.8 kJ/mol
Heat of Fusion
2.2 kJ/mol
Heat of Formation
80.9 kJ/mol
Molar Heat Capacity
31.06 J/(mol K)
Specific Heat Capacity
0.363 J/(g⋅K)
Thermal Conductivity
58.2 W/(m K)
Gas Basicity
Dipole Polarizability
319.8 a₀
C6 Dispersion Coefficient
4,769 a₀
Oxidation States-1, 1
Color
Silver
Crystal StructureBody Centered Cubic (BCC)
Lattice Constant
5.59 Å
Bulk Modulus
Electrical Resistivity
Electron Configuration[Kr] 5s1
Magnetic Ordering
Magnetic Susceptibility
PhaseSolid
Poisson Ratio
Shear Modulus
Young's Modulus
Allotropes
Alternate Names
Adiabatic Index
Appearance
Electric Conductivity
Critical Pressure
Critical Temperature
Curie Point
Electrical
Hardness
Magnetic Susceptibility
Magnetic
Neel Point
Neutron Cross Section
Neutron Mass Absorption
Gas Phase
Quantum Numbers
Refractive Index
Space Group
Speed of Sound
Superconducting Point
Thermal Expansion
Valence Electrons
Classification
CategoryAlkali metals, Alkali metals
CAS GroupIA
IUPAC GroupIA
Glawe Number9
Mendeleev Number4
Pettifor Number9
Geochemical Classalkali metal
Goldschmidt Classlitophile
Radioactivity
RadioactiveNo
Decay Mode
Half-Life
Lifetime
Abundance
Abundance in Earth's crust
Abundance in Oceans
0.12 mg/L
Abundance in Human Body
Abundance in Meteor
Abundance in Sun
Abundance in Universe1×10-6%

Isotopes of Rubidium

Stable Isotopes
85Rb 87Rb
Unstable Isotopes
71Rb 72Rb 73Rb 74Rb 75Rb 76Rb 77Rb 78Rb 79Rb 80Rb 81Rb 82Rb 83Rb 84Rb 86Rb 88Rb 89Rb 90Rb 91Rb 92Rb 93Rb 94Rb 95Rb 96Rb 97Rb 98Rb 99Rb 100Rb 101Rb 102Rb

History

German chemists Robert Bunsen and Gustav Kirchhoff discovered rubidium in 1861 by the newly developed method of flame spectroscopy. The separation of the metal was tried by Bunsen, but he never got samples with more than 18% of Rubidium. The separation of the metal was only accomplished by George de Hevesy, through the hydrolysis of melted rubidium hydroxide. From the Latin word rubidus, deepest red

DiscoverersR. Bunsen, G. Kirchoff
Discovery LocationGermany
Discovery Year1861
Name OriginLatin: rubidus (deep red); the color its salts impart to flames.
Rubidium is not known to be toxic
Rubidium burns with a reddish-violet flame color

Uses

Rubidium is used as a getter in vacuum tubes and as a photocell component. Rubidium compounds are sometimes used in fireworks to give them a purple color. Rubidium salts are used in glasses and ceramics. Rubidium-87 is slightly radioactive and has been used extensively in dating rocks. Used as a catalyst, photocells, and vacuum and cathode-ray tubes.

Sources

Occurs abundantly, but so widespread that production is limited. Usually obtained from lithium production.