Rubidium

37
Rb
Group
1
Period
5
Block
s
Protons
Electrons
Neutrons
37
37
48
General Properties
Atomic Number
37
Atomic Weight
85.4678
Mass Number
85
Category
Alkali metals
Color
Silver
Radioactive
No
From the Latin word rubidus, deepest red
Crystal Structure
Body Centered Cubic
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.
Electrons per shell
2, 8, 18, 8, 1
Electron Configuration
[Kr] 5s1
Rb
Rubidium burns with a reddish-violet flame color
Physical Properties
Phase
Solid
Density
1.532 g/cm3
Melting Point
312.46 K | 39.31 °C | 102.76 °F
Boiling Point
961.15 K | 688 °C | 1270.4 °F
Heat of Fusion
2.19 kJ/mol
Heat of Vaporization
72 kJ/mol
Specific Heat Capacity
0.363 J/g·K
Abundance in Earth's crust
0.006%
Abundance in Universe
1×10-6%
Rubidium
Image Credits: Wikimedia Commons (Dnn87)
Rubidium metal sample from the Dennis s.k collection
CAS Number
7440-17-7
PubChem CID Number
5357696
Atomic Properties
Atomic Radius
248 pm
Covalent Radius
220 pm
Electronegativity
0.82 (Pauling scale)
Ionization Potential
4.1771 eV
Atomic Volume
55.9 cm3/mol
Thermal Conductivity
0.582 W/cm·K
Oxidation States
-1, 1
Applications
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.
Rubidium is not known to be toxic
Isotopes
Stable Isotopes
85Rb
Unstable Isotopes
71Rb, 72Rb, 73Rb, 74Rb, 75Rb, 76Rb, 77Rb, 78Rb, 79Rb, 80Rb, 81Rb, 82Rb, 83Rb, 84Rb, 86Rb, 87Rb, 88Rb, 89Rb, 90Rb, 91Rb, 92Rb, 93Rb, 94Rb, 95Rb, 96Rb, 97Rb, 98Rb, 99Rb, 100Rb, 101Rb, 102Rb