RUBIDIUM, Rb (37)

Rubidium is a soft, silvery-white metallic element of the alkali metal group. Elemental rubidium is highly reactive, with properties similar to those of other alkali metals, such as very rapid oxidation in air. Natural rubidium is a mix of two isotopes: 85Rb, the only stable one, constitutes 72% of it. The remaining 28% is the slightly radioactive 87Rb with a half-life of 49 billion years—more than three times longer than the estimated age of the universe.

ELEMENT BRIEF

1861 by Robert Bunsen and Gustav Kirchhoff, Germany.

DISCOVERY

Latin, 'rubidius' meaning 'dark red' or 'deepest red'.

ETYMOLOGY

Rubidium

ELEMENT

Rb

SYMBOL

37

ATOMIC NUMBER

7440-17-7

CAS NUMBER

ELEMENTAL SPECTRUM

Silver

ELEMENTAL COLOUR

-

REFRACTIVE INDEX

-

POISSON RATIO

55.788 cm³

MOLAR VOLUME

216.00k Pa, 2.131'8 Atm

BRINELL HARDNESS

0.30

MOHS HARDNESS

-

VICKERS HARDNESS

1,300 m/s, Mach 3.790'1

SPEED OF SOUND

2.50G Pa, 24.673'1k Atm

BULK MODULUS

-

SHEAR MODULUS

2.40G Pa, 23.686'2k Atm

YOUNG MODULUS

ALLOTROPES

312.46 K, 39.31 °C

MELTING POINT

961.15 K, 688.00 °C

BOILING POINT

-

AUTOMATIC IGNITION

-

FLASHPOINT

2,093.00 K, 1,819.85 °C

CRITICAL TEMPERATURE

16.00M Pa, 158 Atm

CRITICAL PRESSURE

58.000'000 W/(m K)

THERMAL CONDUCTIVITY

-

THERMAL EXPANSION

364.00 J/(kg K)

SPECIFIC HEAT

2.190 kJ/mol

HEAT FUSION

72.000 kJ/mol

HEAT VAPORISATION

-

HEAT COMBUSTION

-

CURIE POINT

-

NEEL POINT

-

ADIABATIC INDEX

Solid

PHASE

Conductor

ELECTRICAL TYPE

8.30M S/m

CONDUCTIVITY

120.00n Ω.m

RESISTIVITY

-

SUPERCONDUCTING POINT

-

MAGNETIC TYPE

0.000'000'002'6

MASS SUSCEPTIBILITY

0.000'000'000'222'00

MOLAR SUSCEPTIBILITY

0.000'003'980'00

VOLUME SUSCEPTIBILITY

Alkali Metal

CLASSIFICATION

85.467'663'6

ATOMIC WEIGHT

265 pm

ATOMIC RADIUS

210 pm

COVALENT RADIUS SINGLE BOND

202 pm

COVALENT RADIUS DOUBLE BOND

-

COVALENT RADIUS TRIPLE BOND

303 pm

VAN DER WAALS RADIUS

[Ar]4s²3d¹⁰4p⁶

ELECTRON CONFIGURATION

Cubic, Body-centred

CRYSTAL STRUCTURE

1.532'00 g/cm³

DENSITY AS SOLID

1.460'00 g/cm³

DENSITY AS LIQUID

-

DENSITY AS GAS

lm_3m

SPACE GROUP NAME

229

SPACE GROUP NUMBER

π/2, π/2 π/2

LATTICE ANGLES

558.5, 558.5 558.5 pm

LATTICE CONSTANTS

1

VALENCE

0.82

ELECTRONEGATIVITY

46.89 kJ/mol

ELECTRON AFFINITY

IONISATION ENERGY