Rubidium

Notable characteristics

Rubidium is the second most electropositive of the stable alkali elements and liquefies at high ambient temperature (102.7 °F = 39.3 °C). Like other group 1 elements this metal reacts violently in water. In common with potassium and caesium this reaction is usually vigorous enough to ignite the liberated potassium. The element gives a reddish-violet color to a flame, hence its name.

Uses

Potential or current uses of rubidium include:

• A Bose-Einstein condensate.
• A working fluid in vapor turbines.
• A getter in vacuum tubes.
• A photocell component.
• The resonant element in atomic clocks. This is due to the hyperfine structure of Rubidium's energy levels.
• An ingredient in special types of glass.
• The production of oxygen.
• The study of potassium ion channels in biology.
• Rubidium vapor has been used to make atomic magnetometers. ⁸⁷Rb is currently being used, with other alkali metals, in the development of spin-exchange relaxation-free (SERF) magnetometers.^[1]

Rubidium is easily ionized, so it has been considered for use in ion engines for space vehicles (but xenon are more efficient for this purpose).

Rubidium compounds are sometimes used in fireworks to give them a purple color.

batteries and in other applications.

Rubidium has also been considered for use in a magnetohydrodynamic principle, where rubidium ions are formed by heat at high temperature and passed through a magnetic field. These conduct electricity and act like an armature of a generator thereby generating an electric current.

Rubidium, particularly ⁸⁷Rb, in the form of vapor, is one of the most commonly used atomic species employed for diode laser light at the relevant wavelength, and the moderate temperatures required to obtain substantial vapor pressures.

Rubidium has been used for polarizing ³He (that is, producing volumes of magnetized ³He gas, with the nuclear spins aligned toward a particular direction in space, rather than randomly). Rubidium vapor is optically pumped by a laser and the polarized Rb polarizes ³He by the hyperfine interaction.^[2] Spin-polarized ³He cells are becoming popular for neutron polarization measurements and for producing polarized neutron beams for other purposes.^[3]

History

Rubidium (L rubidus, deepest red) was discovered in 1861 by spectroscope. However, this element had minimal industrial use until the 1920s. Historically, the most important use for rubidium has been in research and development, primarily in chemical and electronic applications.

Occurrence

Rubidium is about the sixteenth most abundant metal in the Earth's crust, roughly as abundant as zinc and rather more common than copper. It occurs naturally in the minerals pollucite at Bernic Lake, Manitoba.

Rubidium metal can be produced by gram.

Isotopes

Main article: Isotopes of rubidium

There are 24 Bq/g, enough to fog photographic film in approximately 30 to 60 days.

Rb-87 has a Rubidium-Strontium dating for a more detailed discussion.

Compounds

Rubidium hydroxide is the starting material for most rubidium-based chemical processes; rubidium carbonate is used in some optical glasses.

Rubidium has a number of superoxide RbO₂. Rubidium forms salts with most anions. Some common rubidium compounds are rubidium chloride (RbCl), rubidium monoxide (Rb₂O) and rubidium copper sulfate Rb₂SO₄·CuSO₄·6H₂0). A compound of rubidium, silver and iodine, RbAg₄I₅, has interesting electrical characteristics and might be useful in thin film batteries.^{[citation needed]}

Precautions

Rubidium reacts violently with water and can cause fires. To ensure both health and safety and purity, this element must be kept under a dry atmosphere.

Biological effects

Rubidium, like sodium and potassium, is almost always in its +1 oxidation state. The human body tends to treat Rb⁺ ions as if they were potassium ions, and therefore concentrates rubidium in the body's electrolytic fluid. The ions are not particularly toxic, and are relatively quickly removed in the sweat and urine. However, taken in excess it can be dangerous.

See also

v • d • e Alkali Metals
Lithium Li Atomic Number: 3 Atomic Weight: 6.941 Melting Point: 453.69 Boiling Point: 1615 Electronegativity: 0.98	|		Sodium Na Atomic Number: 11 Atomic Weight: 22.990 Melting Point: 370.87 Boiling Point: 1156 Electronegativity: 0.96	|		Potassium K Atomic Number: 19 Atomic Weight: 39.098 Melting Point: 336.58 Boiling Point: 1032 Electronegativity: 0.82	|		Rubidium Rb Atomic Number: 37 Atomic Weight: 85.468 Melting Point: 312.46 Boiling Point: 961 Electronegativity: 0.82	|		Caesium Cs Atomic Number: 55 Atomic Weight: 132.905 Melting Point: 301.59 Boiling Point: 944 Electronegativity: 0.79	|		Francium Fr Atomic Number: 87 Atomic Weight: (223) Melting Point: ?295 Boiling Point: ?950 Electronegativity: 0.7

• Rubidium compounds

References

Sources

• Los Alamos National Laboratory – Rubidium
• Louis Meites, Handbook of Analytical Chemistry (New York: McGraw-Hill Book Company, 1963)