Element Rubidium

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  • Topic: Rubidium, Caesium, Lithium
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  • Published : December 1, 2012
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Origin of name: from the Latin word "rubidius" meaning "dark red" or "deepest red".

Atomic Number: 37

Symbol: Rb

Atomic Weight: 85.4678

Say what? Rubidium is pronounced as roo-BID-ee-em.

Discovery: R. Bunsen, G. Kirchoff 1861 (Germany), discovered rubidium in the mineral petalite via its dark red spectral lines.

Element Classification: Alkali Metal

Density (g/cc): 1.532

Melting Point (K): 312.2

Boiling Point (K): 961

Appearance: soft, silvery-white, highly reactive metal

Atomic Radius (pm): 248

Atomic Volume (cc/mol): 55.9

Covalent Radius (pm): 216

Ionic Radius: 147 (+1e)

Specific Heat (@20°C J/g mol): 0.360

Fusion Heat (kJ/mol): 2.20

Evaporation Heat (kJ/mol): 75.8

Pauling Negativity Number: 0.82

First Ionizing Energy (kJ/mol): 402.8

Oxidation States: +1

Lattice Structure: Body-Centered Cubic

Lattice Constant (Å): 5.590

CAS Registry Number: 7440-17-7

Properties: Rubidium may be liquid at room temperature. It ignites spontaneously in air and reacts violently in water, setting fire to the liberated hydrogen. Thus, rubidium must be stored under dry mineral oil, in a vacuum, or in an inert atmosphere. It is a soft, silvery-white metallic element of the alkali group. Rubidium forms amalgams with mercury and alloys with gold, sodium, potassium, and cesium. Rubidium glows red-violet in a flame test.

Rubidium Trivia:

• Rubidium melts just a little above body temperature.
• Rubidium was discovered using spectroscopy. When Bunsen and Kirchoff examined their sample of petalite, they found two red spectral lines deep into the red part of the spectrum. They named their new element rubidium after the Latin word rubidus meaning 'deepest red'. • Rubidium is the second most electropositive element.

• Rubidium can be used to give fireworks a red-violet color. • Rubidium is the 23rd most abundant element in the Earth's crust. •...
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