Caesium (Cs): Properties, Uses and Facts in 3D
Caesium is element 55 on the periodic table, an alkali metal. At room temperature it is a solid. Open it in the 3D Periodic Table to spin its tile, see its electron shells and read its story.
Explore in 3DCaesium quick facts
| Atomic number | 55 |
|---|---|
| Symbol | Cs |
| Atomic mass | 132.905 |
| Category | Alkali Metal |
| Group and period | Group 1, period 6 |
| Block | s-block |
| State at room temperature | Solid |
| Electron configuration | [Xe] 6s¹ |
| Electrons per shell | 2, 8, 18, 18, 8, 1 |
| Discovered | 1860, Bunsen |
What is caesium used for?
- Atomic clocks (SI second definition)
- Infrared detection in night vision
- Oil drilling fluid additive
Interesting facts about caesium
- One second is officially defined by 9,192,631,770 oscillations of caesium-133
- The best caesium fountain clocks are accurate to 1 second in about 300 million years
- Caesium is so reactive with water it explodes on contact even at −116°C
Caesium was discovered in 1860 by Bunsen in Germany.
Where caesium sits on the periodic table
Caesium is in group 1, period 6. Tap any element to open its page.
Other alkali metals
Caesium questions
What is the atomic number of caesium?
Caesium has atomic number 55, so every caesium atom has 55 protons in its nucleus. Its symbol is Cs and its atomic mass is 132.905.
Is caesium a metal?
Caesium is a metal. On the periodic table it is grouped as an alkali metal, found in group 1, period 6.
What is the electron configuration of caesium?
The electron configuration of caesium is [Xe] 6s¹. Its electrons sit in 6 shells: 2, 8, 18, 18, 8, 1.
What is caesium used for?
Caesium is used for atomic clocks (si second definition), infrared detection in night vision and oil drilling fluid additive.
Who discovered caesium?
Caesium was discovered in 1860 by Bunsen in Germany.
The 3D Periodic Table is made by Julian Neagu, a solo founder in London, as part of VisionVix Simulators. It is free to use in the browser on desktop and phone, with no sign-up.