Rubidium

Alkali metal · atomic number 37

3785.46783RbRubidiumSolidAlkali metal

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.

Properties of Rubidium

Element category	Alkali metal
Atomic number	37
Atomic mass	85.46783 u
Phase at STP	Solid
Group	1
Period	5
Block	s
Electron configuration	[Kr] 5s1
Electrons per shell	2, 8, 18, 8, 1
Electronegativity (Pauling)	0.82
Melting point	312.45 K (39 °C)
Boiling point	961 K (688 °C)
Density	1.532 g/cm3
Discovered by	Robert Bunsen

← Krypton · Periodic table · Strontium → Sr

About the alkali metal group

Soft, wildly reactive metals of group 1 — they fizz in water and never occur pure in nature. Lithium, sodium, potassium and friends.

Data: Periodic-Table-JSON (CC BY-SA 3.0) · stored statically on our server. https://en.wikipedia.org/wiki/Rubidium

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🧪 Reactive nonmetal

11 elements: Elements that readily gain or share electrons — the building blocks of water, air, living tissue and most organic chemistry.

🧪 Noble gas

6 elements: Full outer electron shells make these gases almost inert: they barely react, glow in discharge lamps and are used to create unreactive atmospheres.

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6 elements: Soft, wildly reactive metals of group 1 — they fizz in water and never occur pure in nature. Lithium, sodium, potassium and friends.

🧪 Alkaline earth metal

6 elements: Reactive group-2 metals a step calmer than the alkalis: magnesium, calcium and the structural and biological workhorses among them.

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