Cs
Cesium (Atomic Number 55)
Category: alkali | Period 6, Group 1 | Block: s
Most reactive alkali metal; defines physical duration of one second.
Atomic & Physical Constants
- Standard Atomic Weight:
- 132.905451966 u
- Standard State Phase:
- Solid
- Electron Configuration:
- 2, 8, 18, 18, 8, 1
- Electronegativity (Pauling):
- 0.79
- Melting Point:
- 301.7 K
- Boiling Point:
- 944 K
Historical Discovery & Real-World Applications
Industrial & Scientific Uses
International primary atomic clock standard for the second
Discovery History
Discovered by Robert Bunsen (1860).
Study Cesium with Socratic AI Tutor
Get step-by-step orbital hybridization, oxidation state derivations, and reaction practice questions.