Rubidium

Rubidium 85.4678(3)   Rb 37 1s22s22p63s23p63d104s2 4p65s1 [ ? ] Alkali metal: Properties: Soft, silvery-white metal in its solid state.

Rubidium is a chemical element, having the chemical symbol Rb. Its atomic number (the number of protons) is 37. It has a standard atomic weight of 85.4678 g•mol ⁻¹.

Rubidium is considered to be a member of the "Alkali metal" class of element. At a pressure of 101.325 kPa, it has a boiling point of 688 °C and a melting point of 39.3 °C. In its elemental form, Rubidium is a solid at typical room temperatures of 15 − 25 °C.

Isotopes

Rubidium has two naturally occurring isotopes: ⁸⁵Rb with mass (atomic weight) 84.911 7893 and abundance 72.17%, and ⁸⁷Rb with mass 86.909 1835 and abundance 27.83%. The very dilute gas of ground state ⁸⁷Rb atoms at a temperature of 1.7•10⁻⁷ K shows Bose-Einstein condensation.