Rb
Rubidium
Atomic number: 37Mass: 85.468 uCategory: Alkali Metal
About Rubidium
Rubidium is a very soft, silvery-white alkali metal. It is highly reactive and catches fire spontaneously in air. Its name comes from the Latin 'rubidus' (dark red) because of the red spectral lines used to discover it.
Properties
Period
5
Group
1
Block
S
Category
Alkali Metal
Electronegativity
0.82 (Pauling)
Ionization Energy
403 kJ/mol
Melting Point
312 K (39°C)
Boiling Point
961 K (688°C)
Density
1.532 g/cm³
Oxidation States
+1
Electron Configuration
1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 5s¹
[Kr] 5s¹
Shell 1:2e⁻
Shell 2:8e⁻
Shell 3:18e⁻
Shell 4:8e⁻
Shell 5:1e⁻
Real-World Uses
Atomic clocks
Research
Photomultiplier tubes
Medical imaging (PET scans)
Spectroscopy
Fun Fact
Rubidium atomic clocks are so accurate that they lose about 1 second every 300 years — they're used to calibrate GPS satellites!