Yes. Rubidium is a metal, classified as an alkali metal on the periodic table.

How many protons does rubidium have?

Rubidium has 37 protons. Its atomic number is 37, which is also the number of electrons in a neutral atom of rubidium.

What group and period is rubidium in?

Rubidium is in group 1 and period 5 of the periodic table, in the s-block.

What is the atomic mass of rubidium?

The atomic mass of rubidium is 85.468 u (unified atomic mass units).

Element 37

Rubidium (Rb)

Alkali metal · Period 5 · Group 1 · s-block

Rubidium (Rb) is element 37 of the periodic table, an alkali metal in period 5, group 1 (s-block) with an atomic mass of 85.468 and is a solid at standard conditions.

At a glance

Atomic number: 37
Symbol: Rb
Atomic mass: 85.468 u
Category: Alkali metals
Period: 5
Group: 1
Block: s-block
Phase at STP: solid

Electron structure

Electron configuration: 1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 5s1
Shorthand configuration: [Kr] 5s1
Electrons per shell: 2, 8, 18, 8, 1
Oxidation states: -1, +1

Physical properties

Melting point: 312.46 K (39.31 °C)
Boiling point: 961 K (687.85 °C)
Density: 1.532 g/cm³
Phase: solid

Atomic properties

Electronegativity (Pauling): 0.82
Atomic radius: 265 pm
Covalent radius: 220 pm
Van der Waals radius: 303 pm
First ionization energy: 403 kJ/mol
Electron affinity: 47 kJ/mol

Notable isotopes

Notable isotopes of Rubidium: mass number, atomic mass, natural abundance, and stability.
Isotope	Mass	Abundance	Stability
Rb-85	84.91179	72.17%	Stable

Common uses

Atomic clocks
Electronics
Fireworks
Photocells

Discovery

Year: 1861
Discovered by: Robert Bunsen, Gustav Kirchhoff
Country: Germany

Frequently asked questions

Is rubidium a metal?: Yes. Rubidium is a metal, classified as an alkali metal on the periodic table.
How many protons does rubidium have?: Rubidium has 37 protons. Its atomic number is 37, which is also the number of electrons in a neutral atom of rubidium.
What group and period is rubidium in?: Rubidium is in group 1 and period 5 of the periodic table, in the s-block.
What is the atomic mass of rubidium?: The atomic mass of rubidium is 85.468 u (unified atomic mass units).

Keep exploring

Rubidium's row is on the printable element property sheet, and its tile is on the periodic table wall chart - the same numbers as above, laid out for A4 or A3 paper.