Cesium (Cs)
Cesium (Cs, element 55) is an alkali metal in group 1, period 6. Atomic mass 132.905, electron configuration [Xe] 6s¹, uses and facts.
About Cesium
Cesium is an alkali metal with the symbol Cs and atomic number 55. It is a solid at room temperature, and it sits in group 1, period 6 of the periodic table. Cesium was discovered in 1860 by Robert Bunsen.
Cesium key facts
- Atomic number: 55
- Symbol: Cs
- Atomic mass: 132.905 u
- Category: alkali metal
- Group: 1
- Period: 6
- State at room temperature: solid
- Electron configuration: [Xe] 6s¹
- Electronegativity (Pauling): 0.79
- Melting point: 301.59 K (28.44 °C)
- Boiling point: 944 K (670.85 °C)
- Density: 1.93 g/cm³
- Common oxidation states: −1, +1
Electron configuration
The electron configuration of cesium is [Xe] 6s¹. The part in brackets is the noble gas core; the rest shows how the outer electrons fill their subshells. Cesium has 1 valence electron.
Uses of cesium
- Atomic clocks
- Drilling fluid
- Photoelectric cells
Did you know?
Cesium atomic clocks define the second, 9,192,631,770 vibrations of cesium-133 = 1 second.
Other elements in group 1 and neighbours
Frequently asked questions
What is the atomic number of cesium?
The atomic number of cesium is 55, which means every cesium atom has 55 protons.
What is the electron configuration of cesium?
The electron configuration of cesium is [Xe] 6s¹.
What group and period is cesium in?
Cesium is an alkali metal in group 1, period 6.
What state is cesium at room temperature?
Cesium is a solid at room temperature.
What is cesium used for?
Cesium is used for atomic clocks, drilling fluid, photoelectric cells.