55 · Cs
Caesium
Discovered by Bunsen and Kirchhoff in 1860.
Identity
- Atomic number
- 55
- Symbol
- Cs
- Canonical name
- Caesium
- Category
- alkali metal
- Group
- 1
- Period
- 6
- Block
- s
- Other names
- cesium
Properties
These quantities come from the Periodic Table JSON compilation. They have not yet been checked, one by one, against CIAAW atomic weights or NIST measurements. A value marked estimated is not a measurement.
- Atomic mass
- 132.905452 u
- Electron configuration
- [Xe] 6s1
- Electrons per shell
- 2, 8, 18, 18, 8, 1
- Standard state
- solid
- Density
- 1.93 g/cm³
- Melting point
- 301.7 K
- Boiling point
- 944 K
- Electronegativity
- 0.79 Pauling
- First ionization energy
- 375.7 kJ/mol
- Electron affinity
- 45.505 kJ/mol
Notable isotopes
This summary is not an inventory of every isotope.
- Cs-133 · 100 % · stable
History
Blue lines
Discovery · jointly credited · 1860
Bunsen and Kirchhoff discover caesium by spectroscopy in the mineral water of Dürkheim.
Etymology
- Theme
- color
- Language
- latin
- Root
- caesius
- Meaning
- sky blue
Scientists
Places and institutions
- Heidelberg — historical setting : Grand Duchy of Baden, then Germany — present country : Germany
See also
Sources
- IUPAC, Periodic Table of the Elements
- Bowserinator, Periodic Table JSON. Compilation secondaire d’où viennent les grandeurs physiques importées (masse, densité, températures, énergies). Elles ne sont pas revérifiées une à une auprès du NIST ou de la CIAAW.
- John Emsley, Nature’s Building Blocks: An A–Z Guide to the Elements