Rb

Rubidium

Identification

CAS Number: 7440-17-7

Discovery Year: 1861

Discoverer: R. Bunsen, G. Kirchoff

Discovery Location: Germany

Properties

Atomic Mass: 85.4678 →Density: 1.53 g/cm³ →

Crust Abundance: 90 mg/kg

Crystal Structure: BCC

Atomic Dimensions

Atomic Radius: 235 pm →

Atomic Radius (Rahm): 240 pm

Covalent Radius: 220.00000000000003 pm →

Van der Waals Radius: 303 pm

Metallic Radius: 216 pm

Atomic Volume: 55.9 cm³/mol

Lattice Constant: 5.59 Å

Thermodynamics

Melting Point: 312.2 K →Boiling Point: 961 K →Specific Heat: 0.36 J/(g·K) →Thermal Conductivity: 58.2 W/(m·K) →Heat of Fusion: 2.2 kJ/mol →Heat of Vaporization: 75.8 kJ/mol →

Heat of Formation: 80.9 kJ/mol

Electronic Structure

Electron Config: [Kr] 5s

Block: s

Period: 5 →Group: 1 →Electronegativity: 0.82 →Electron Affinity: 0.48591999999999996 eV →

Oxidation States: +1

Abundance & Geochemistry

Crust Abundance: 90 mg/kg

Sea Abundance: 0.12 mg/L

Geochemical Class: alkali metal

Goldschmidt Class: litophile

About

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.

Isotopes

Rb-85 85 72.17%

Rb-87 87 27.83%