37 Rb 85.468

Rubidium

alkali metal

Properties

Atomic number
37
Atomic mass
85.468 u
Category
alkali metal
Group
1
Period
5
Block
s-block
State (room temp)
Solid
Outer-shell electrons
1
Electronegativity
0.82 (Pauling)
Density
1.532 g/cm³
Melting point
39.3 °C
Boiling point
687.85 °C

Electron configuration

1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s¹

Noble-gas shorthand: [Kr] 5s¹

Electrons per shell: 2, 8, 18, 8, 1, which is 1 in the outermost shell.

Related: electron configuration, the Bohr model, valence electrons.

Rb
Bohr model; outer-shell electrons in blue

About Rubidium

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.

Rubidium: frequently asked questions

What is Rubidium?
Rubidium (Rb) is the chemical element with atomic number 37. It is a metal: specifically an alkali metal.
What is the atomic number of Rubidium?
Rubidium's atomic number is 37, which means every Rubidium atom has 37 protons in its nucleus.
What is the electron configuration of Rubidium?
The electron configuration of Rubidium is 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s1 (noble-gas shorthand: [Kr] 5s1). Its electrons are arranged in shells of 2, 8, 18, 8, 1, with 1 in the outermost shell.
Is Rubidium a metal or a nonmetal?
Rubidium is a metal: specifically an alkali metal.
What group and period is Rubidium in?
Rubidium is in group 1 and period 5 of the periodic table.
Is Rubidium a solid, liquid, or gas?
At room temperature, Rubidium is a solid.

Position in the periodic table

Open the interactive periodic table →

Data compiled from Wikipedia, PubChem, and IUPAC. Source.