Rubidium is a chemical element with symbol Rb and atomic number 37. Rubidium is a soft, silvery-white metallic element of the alkali metal group, with an atomic mass of 85.4678. Elemental rubidium is highly reactive, with properties similar to those of other alkali metals, such as very rapid oxidation in air.
Three reasons Rubidium stands out
- 1
Highly reactive and soft metal.
- 2
It is so soft it can be easily cut with a spoon.
- 3
Its crimson-red spectral lines were what allowed scientists to identify it as a new element in 1861.
An atomic clock’s favorite transition
Rubidium is a soft, reactive metal that must be protected from air. Its atoms respond to microwave frequencies with exceptional consistency, enabling compact atomic clocks used in telecommunications and navigation. Rubidium isotopes also help physicists cool gases toward quantum states where matter behaves collectively.