Rubidium (Rb)

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 a standard atomic weight of 85.4678.

Atomic Number

37

Atomic Mass

85.468 u

Category

alkali metal

Phase

solid

Density

1.532 g/cm³

Electron Shells

2, 8, 18, 8, 1

Atomic Structure

Protons: 37 • Electrons: 37 • Neutrons: Varies by isotope

Electron Configuration: 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s¹

Discovery

1861 • Robert Bunsen, Gustav Kirchhoff