Cesium · Cs Cesium
Cesium atomic transitions are used for time measurement; also used in cold atom research.
- atomic number / Atomic number
- 55
- atomic weight / Atomic mass
- 132.9054520 u
- Family/Group
- 1
- Period · Block / Period · Block
- 6 · s
- Category / Category
- Alkali metal · Alkali metal
- State / State
- solid state
- Electron configuration
- [Xe]6s1
- Oxidation states / Oxidation states
- +1
- Electronegativity / Electronegativity
- 0.79（Pauling）
- Density / Density
- 1.93 g/cm³
- Melting point / Melting point
- 301.59 K
- Boiling point / Boiling point
- 944 K
- Atomic radius / Atomic radius
- 343 pm（van der Waals）
- First ionization energy
- 3.894 eV
- Discovery year / Discovery
- 1860
attribute description and data source
properties taken from PubChem periodic table snapshot (2026-10-04). Atomic weights may be reference values or representative isotope masses and cannot be considered exact constants for all samples; density, phase transition points, and phase states depend on temperature, pressure, and allotropes. The solidification of helium requires pressure. Some properties of radioactive and superheavy elements are predicted values, and missing items are marked as not included. Please check the original source and experimental conditions for precise calculations.