Caesium
Cesio (Cs, Z=55)
- Date
- 1860 · confidence high
- Place
- Heidelberg, Germany
- Credited to
- Robert Bunsen and Gustav Kirchhoff
- People
- 👤 Gustav Kirchhoff1824–1887👤 Robert Bunsen1811–1899
- Field
- Matter & energy
What was discovered
The first element discovered by spectroscopy: Bunsen and Kirchhoff saw two blue lines in the residue of mineral water from Dürkheim.
The name comes from the Latin 'caesius', sky blue.
What it led to
- The definition of the second (1967) by the caesium atomic clock
- Spectroscopy as a method of discovery
- Photoelectric cells
Built on
- Bunsen burner1855
- Spectral analysis (Bunsen-Kirchhoff)1859-1860
- Bunsen-Kirchhoff spectroscope
Made possible
- Caesium atomic clock1955
- Global Positioning System (GPS)1978-1995
- GPS (dependent on atomic clocks)