Rubidium (Rb)
alkali-metalSolid
Standard Atomic Weight
85.4678 uElectron configuration
[Kr] 5s1Melting point
39.31 °CBoiling point
687.85 °CDensity
1530 kg/m³Oxidation states
−1, +1Electronegativity (Pauling)
0.82Ionization energy (1st)
4.177128 eVDiscovery year
1861Atomic radius
235 pmDetails
Rubidium is a soft alkali metal of group 1, chemically close to potassium and cesium. Natural rubidium is a mixture dominated by stable ⁸⁵Rb with radioactive ⁸⁷Rb, whose very long half-life makes it important in geochronology. The element is not mined as a principal metal; it is obtained from minerals and brines where it substitutes for potassium. Its low ionization energy and convenient atomic transitions make rubidium useful in precision physics.
Rubidium can be liquid at room temperature. It is a soft, silvery-white metallic element of the alkali group and is the second most electropositive and alkaline element. It ignites spontaneously in air and reacts violently in water, setting fire to the liberated hydrogen. As with other alkali metals, it forms amalgams with mercury and it alloys with gold, cesium, sodium, and potassium. It colors a flame yellowish violet. Rubidium metal can be prepared by reducing rubidium chloride with calcium, and by a number of other methods. It must be kept under a dry mineral oil or in a vacuum or inert atmosphere.
The name derives from the Latin rubidus for "deepest red" because of the two deep red lines in its spectra. Rubidium was discovered in the mineral lepidolite by the German chemist Robert Wilhelm Bunsen and the German physicist Gustav-Robert Kirchoff in 1861. Bunsen isolated rubidium in 1863.
Rubidium was discovered by the German chemists Robert Bunsen and Gustav Kirchhoff in 1861 while analyzing samples of the mineral lepidolite (KLi2Al(Al, Si)3O10(F, OH)2) with a device called a spectroscope. The sample produced a set of deep red spectral lines they had never seen before. Bunsen was eventually able to isolate samples of rubidium metal. Today, most rubidium is obtained as a byproduct of refining lithium.
From the Latin word rubidus, deepest red. Discovered in 1861 by Bunsen and Kirchoff in the mineral lepidolite by use of the spectroscope.
Pure rubidium is a very soft, silvery-white metal that quickly tarnishes in air. It melts just above ordinary room temperature and can be cut easily when protected from moisture and oxygen. Samples are kept under inert gas, vacuum, or dry mineral oil.
Rubidium has specialized rather than bulk uses. Rubidium vapor cells are used in atomic clocks, frequency standards, magnetometers, and some laser-cooling experiments, often using ⁸⁷Rb because its hyperfine transition is convenient. Rubidium compounds have been used in photocathodes, research electronics, and laboratory studies of ion transport. ⁸⁷Rb to ⁸⁷Sr decay underlies rubidium–strontium dating of minerals and rocks. There is no large structural or metallurgical use for the metal.
Rubidium is used in vacuum tubes as a getter, a material that combines with and removes trace gases from vacuum tubes. It is also used in the manufacture of photocells and in special glasses. Since it is easily ionized, it might be used as a propellant in ion engines on spacecraft. Recent discoveries of large deposits of rubidium suggest that its usefulness will increase as its properties become better understood.
Rubidium forms a large number of compounds, although none of them has any significant commercial application. Some of the 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.
Because rubidium can be easily ionized, it has been considered for use in "ion engines" for space vehicles; however, cesium is somewhat more efficient for this purpose. It is also proposed for use as a working fluid for vapor turbines and for use in a thermoelectric generator using the 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 amature of a generator thereby generating an electric current. Rubidium is used as a getter in vacuum tubes and as a photocell component. It has been used in making special glasses. RbAg4I5 is important, as it has the highest room conductivity of any known ionic crystal. At 20°C its conductivity is about the same as dilute sulfuric acid. This suggests use in thin film batteries and other applications.
Isotopes in Biology
Due to biological similarities between rubidium and potassium, the radionuclide 86Rb (with a half-life of 18.7 days) is used as a tracer in biological or medical investigations for applications where the half-life of the radioactive-tracer 42K (half-life of 0.5 day) is too short [110] AUS-e-TUTE for Astute Science Students. Chemistry Tutorial: Summary of Radioactive Particles, Isotopes, Properties and Uses, AUS-e-TUTE for Astute Science Students (2014), Feb. 24; http://www.ausetute.com.au/nuclesum.html.. 86Rb (with a half-life of 18.7 days) has been used measure the metabolism in small vertebrates (Fig. IUPAC.37.1), such as dunnarts (furry, narrow-footed marsupials about the size of a mouse) [291] S. Tomlinson, S. K. Maloney, P. C. Withers, C. C. Voigt, A. P. Cruz-Neto. Methods Ecol. Evol.4, 619 (2013).. The advantage of this technique over the standard doubly labelled water method, using water enriched in 2H and 18O, include lower equipment requirements, lower technical expertise, and longer time spans over which measurements can be made. This technique could be very useful for measuring the metabolism of amphibians and insects.
Isotopes in Geochronology
87Rb (with a half-life of 4.97×1010 years) is a long-lived radioisotope that is transformed into 87Sr by emission of a beta-minus particle (an electron) and an antineutrino. From the abundance of 87Sr and the Rb/Sr amount ratio in a rock, its age of crystallization can be calculated. Rb/Sr dating is one of the most widely employed techniques for dating geological samples [292] M. A. Geyh, H. Schleicher. Absolute Age Determination: Physical and Chemical Dating Methods and Their Application, p. 503, Springer-Verlag, Berlin (1990)..
Isotopes in Medicine
82Rb (with a half-life of 75 s) acts similarly to potassium and is used for imaging of the heart to better assess heart muscle function as a radioactive analog to potassium [293] J. vom Dahl, O. Muzik, E. R. Wolfe, C. Allman, G. Hutchins, M. Schwaiger. Circulation93, 238 (1996)., [294] K. L. Gould, K. Yoshida, M. J. Hess, M. Haynie, N. Mullani, R. W. Smalling. J. Nucl. Med.32, 1 (1991).. 82Rb is being considered as an alternative to highly-enriched uranium for producing medically important radioisotopes [293] J. vom Dahl, O. Muzik, E. R. Wolfe, C. Allman, G. Hutchins, M. Schwaiger. Circulation93, 238 (1996)..
Rubidium almost always forms the +1 oxidation state as Rb⁺. Its common salts resemble those of potassium and cesium, including rubidium chloride (RbCl), rubidium bromide (RbBr), rubidium nitrate (RbNO₃), and rubidium carbonate (Rb₂CO₃). The oxide chemistry is sensitive to oxygen conditions; rubidium can form rubidium oxide (Rb₂O), rubidium peroxide (Rb₂O₂), and rubidium superoxide (RbO₂). Rubidium hydroxide (RbOH) is a strong, highly caustic base. Complex salts and alum-type compounds are known, but lower oxidation states are not normal chemistry for the element.
See more information at the Rubidium compound page.
Metallic rubidium is highly reactive and can ignite or explode on contact with water because hydrogen gas, H₂, and rubidium hydroxide (RbOH) are produced with heat. It also reacts rapidly with air and should be handled only under dry inert conditions. Soluble rubidium salts can affect biological ion balance because Rb⁺ partly mimics K⁺, though rubidium is not an essential nutrient. Natural ⁸⁷Rb is weakly radioactive, but its specific activity is low compared with many regulated radionuclides.
Rubidium occurs dispersed in the crust, chiefly substituting for potassium in feldspars, micas, and evaporite or brine systems. It is mobile as Rb⁺ in water but is also adsorbed or fixed by clays and potassium-bearing minerals. Plants can take up rubidium because of its similarity to potassium, yet it has no established essential biological function. Environmental releases are normally small and associated with mineral processing, laboratory use, or weathering.
Rubidium supply is small and specialized. It is usually recovered as a by-product from lithium and cesium-bearing minerals such as lepidolite and pollucite, or from selected brines, rather than from ores mined solely for rubidium. Production involves separation from abundant potassium and chemically similar cesium, which limits availability and keeps costs high for high-purity material. Demand is driven mainly by atomic-clock, research, and specialty chemical markets. Recycling is limited, though sealed vapor-cell devices contain only small amounts.
The element is much more abundant than was thought several years ago. It is now considered to be the 16th most abundant element in the earth's crust. Rubidium occurs in pollucite, leucite, and zinnwaldite, which contains traces up to 1%, in the form of the oxide. It is found in lepidolite to the extent of about 1.5%, and is recovered commercially from this source. Potassium minerals, such as those found at Searles Lake, California, and potassium chloride recovered from the brines in Michigan also contain the element and are commercial sources. It is also found along with cesium in the extensive deposits of pollucite at Bernic Lake, Manitoba.
Rubidium is a trace element in the cosmos. Its isotopes are made mainly by neutron-capture processes in evolved stars, with contributions from both slow and rapid neutron-capture pathways. In planetary materials it behaves as a moderately incompatible lithophile element and follows potassium during rock differentiation. The ⁸⁷Rb–⁸⁷Sr system is widely used to study the ages and source histories of terrestrial and meteoritic materials.
- Rubidium was discovered spectroscopically from deep red emission lines, which inspired its name.
- A sealed rubidium vapor cell can serve as the frequency reference in a compact atomic clock.
- Natural rubidium contains enough ⁸⁷Rb for geologic dating despite its very long half-life.
- Rubidium metal may be liquid in a warm room because its melting point is only about 39 °C.
- Rubidium ions can enter some potassium channels, making rubidium useful as a tracer in physiology research.
Images
Properties
Physical
- Atomic radius (empirical)
- 235 pm Compare Atomic radius (empirical) of all elements →
- Covalent radius
- 220 pm Compare Covalent radius of all elements →
- Van der Waals radius
- 303 pm Compare Van der Waals radius of all elements →
- Metallic radius
- 216 pm Compare Metallic radius of all elements →
- Density
- 1530 kg/m³ Compare Density of all elements →
- Molar volume
- 0.0559 L/mol
- Phase at STP
- Solid Compare Phase at STP of all elements →
- Melting point
- 39.31 °C Compare Melting point of all elements →
- Boiling point
- 687.85 °C Compare Boiling point of all elements →
- Thermal conductivity
- 58.2 W/(m·K) Compare Thermal conductivity of all elements →
- Specific heat capacity
- 0.363 J/(g·K) Compare Specific heat capacity of all elements →
- Molar heat capacity
- 31.06 J/(mol·K) Compare Molar heat capacity of all elements →
- Crystal structure
- Body-centered cubic Compare Crystal structure of all elements →
Chemical
- Electronegativity (Pauling)
- 0.82 Compare Electronegativity (Pauling) of all elements →
- Electronegativity (Allen)
- 0.706
- Electron affinity
- 0.4859 eV
- Ionization energy (1st)
- 4.177128 eV Compare Ionization energy (1st) of all elements →
- Ionization energy (2nd)
- 27.289634 eV Compare Ionization energy (2nd) of all elements →
- Ionization energy (3rd)
- 39.247135 eV Compare Ionization energy (3rd) of all elements →
- Ionization energy (4th)
- 52.20018 eV Compare Ionization energy (4th) of all elements →
- Ionization energy (5th)
- 68.440236 eV Compare Ionization energy (5th) of all elements →
- Oxidation states
- −1, +1 Compare Oxidation states of all elements →
- Valence electrons
- 1 Compare Valence electrons of all elements →
- Electron configuration
- [Kr] 5s1
Thermodynamic
- Triple point (temperature)
- 39.26 °C
- Critical point (temperature)
- 1820 °C
- Critical point (pressure)
- 1.6e+7 Pa
- Heat of fusion
- 0.02269783 eV Compare Heat of fusion of all elements →
- Heat of vaporization
- 0.71513707 eV Compare Heat of vaporization of all elements →
- Heat of sublimation
- 0.84987304 eV
- Heat of atomization
- 0.84987304 eV
- Atomization enthalpy
- 0.8384723 eV
Nuclear
- Protons
- 37 Compare Protons of all elements →
- Neutrons
- 48 Compare Neutrons of all elements →
- Known isotopes
- 34 Compare Known isotopes of all elements →
- Stable isotopes
- 1 Compare Stable isotopes of all elements →
- Most stable isotope
- Rb-85
- Discovery year
- 1861
Abundance
- Abundance (Earth's crust)
- 90 mg/kg Compare Abundance (Earth's crust) of all elements →
- Abundance (ocean)
- 0.12 mg/L Compare Abundance (ocean) of all elements →
Crystal Structure
- Lattice constant a
- 559 pm
Electronic Structure
- Electrons per shell
- 2, 8, 18, 8, 1 Compare Electrons per shell of all elements →
Identifiers
- CAS number
- 7440-17-7 Compare CAS number of all elements →
- Term symbol
- 2S1/2
- InChI
- InChI=1S/Rb
- InChI Key
- IGLNJRXAVVLDKE-UHFFFAOYSA-N
Electron Configuration Measured
Rb: 5s¹[Kr] 5s¹1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 5s¹Atomic model
Isotopes change neutron count, mass, and stability — not the electron configuration of a neutral atom.
Schematic atomic model, not to scale.
Atomic Fingerprint
Emission / Absorption Spectrum
Isotope Distribution
| Mass number | Atomic mass (u) | Natural abundance | Half-life |
|---|---|---|---|
| 85 Stable | 84.9117897379 ± 0.0000000054 | 72.1700% | Stable |
Phase / State
Reason: 14.3 °C below melting point (39.31 °C)
Schematic, not to scale
Phase transition points
Transition energies
Energy required to melt 1 mol at melting point
Energy required to vaporize 1 mol at boiling point
Energy required to sublime 1 mol at sublimation point
Density
At standard conditions
At standard conditions
Advanced
Atomic Spectra
Showing 10 of 37. Sorted by ion charge (ascending).
Lines Holdings ?
| Ion | Charge | Total lines | Transition probabilities | Level designations |
|---|---|---|---|---|
| Rb I | 0 | 213 | 40 | 213 |
| Rb II | +1 | 699 | 49 | 602 |
| Rb III | +2 | 232 | 0 | 230 |
| Rb IV | +3 | 573 | 0 | 573 |
| Rb V | +4 | 34 | 13 | 34 |
| Rb VI | +5 | 34 | 32 | 34 |
| Rb VII | +6 | 26 | 10 | 26 |
| Rb VIII | +7 | 34 | 26 | 34 |
| Rb IX | +8 | 40 | 17 | 40 |
| Rb X | +9 | 64 | 29 | 64 |
Levels Holdings ?
| Ion | Charge | Levels |
|---|---|---|
| Rb I | 0 | 240 |
| Rb II | +1 | 166 |
| Rb III | +2 | 92 |
| Rb IV | +3 | 131 |
| Rb V | +4 | 21 |
| Rb VI | +5 | 20 |
| Rb VII | +6 | 21 |
| Rb VIII | +7 | 25 |
| Rb IX | +8 | 37 |
| Rb X | +9 | 41 |
Ionic Radii
| Charge | Coordination | Spin | Radius |
|---|---|---|---|
| +1 | 6 | N/A | 152 pm |
| +1 | 7 | N/A | 156 pm |
| +1 | 8 | N/A | 161 pm |
| +1 | 9 | N/A | 163 pm |
| +1 | 10 | N/A | 166 pm |
| +1 | 11 | N/A | 169 pm |
| +1 | 12 | N/A | 172 pm |
| +1 | 14 | N/A | 183 pm |
Compounds
Isotopes (1)
Twenty four isotopes of rubidium are known. Naturally occurring rubidium is made of two isotopes, 85Rb and 87Rb. Rubidium-87 is present to the extent of 27.85% in natural rubidium and is a beta emitter with a half-life of 4.9 x 1010 years. Ordinary rubidium is sufficiently radioactive to expose a photographic film in about 30 to 60 days. Rubidium forms four oxides: Rb2O, Rb2O2, Rb2O3, Rb2O4.
| Mass number | Atomic mass (u) | Natural abundance | Half-life | Decay mode | |
|---|---|---|---|---|---|
| 85 Stable | 84.9117897379 ± 0.0000000054 | 72.1700% ± 0.0200% | Stable | stable |
Spectral Lines
Showing 50 of 202. Only spectral lines with measured intensity are shown by default.
| Wavelength (nm) | Intensity | Ion stage | Type | Transition | Accuracy | Source | |
|---|---|---|---|---|---|---|---|
| 424.439 nm | 90000 | Rb II | emission | 4p5.(2P*<3/2>).5s 2[3/2]* → 4p5.(2P*<3/2>).5p 2[5/2] | Measured | NIST | |
| 477.5954 nm | 30000 | Rb II | emission | 4p5.(2P*<3/2>).5s 2[3/2]* → 4p5.(2P*<3/2>).5p 2[1/2] | Measured | NIST | |
| 394.051 nm | 25000 | Rb II | emission | 4p5.(2P*<3/2>).5s 2[3/2]* → 4p5.(2P*<3/2>).5p 2[3/2] | Measured | NIST | |
| 457.1765 nm | 20000 | Rb II | emission | 4p5.(2P*<3/2>).5s 2[3/2]* → 4p5.(2P*<3/2>).5p 2[5/2] | Measured | NIST | |
| 427.3141 nm | 15000 | Rb II | emission | 4p5.(2P*<3/2>).5s 2[3/2]* → 4p5.(2P*<3/2>).5p 2[5/2] | Measured | NIST | |
| 464.8557 nm | 10000 | Rb II | emission | 4p5.4d 3P* → 4p5.(2P*<1/2>).5p 2[3/2] | Measured | NIST | |
| 515.2081 nm | 10000 | Rb II | emission | 4p5.(2P*<3/2>).5s 2[3/2]* → 4p5.(2P*<3/2>).5p 2[1/2] | Measured | NIST | |
| 645.833 nm | 10000 | Rb II | emission | 4p5.(2P*<1/2>).5s 2[1/2]* → 4p5.(2P*<3/2>).5p 2[1/2] | Measured | NIST | |
| 552.2776 nm | 5000 | Rb II | emission | 4p5.(2P*<1/2>).5s 2[1/2]* → 4p5.(2P*<3/2>).5p 2[3/2] | Measured | NIST | |
| 656.0799 nm | 5000 | Rb II | emission | 4p5.4d 3F* → 4p5.(2P*<1/2>).5p 2[3/2] | Measured | NIST | |
| 419.3079 nm | 3500 | Rb II | emission | 4p5.(2P*<3/2>).5s 2[3/2]* → 4p5.(2P*<3/2>).5p 2[3/2] | Measured | NIST | |
| 453.0333 nm | 3000 | Rb II | emission | 4p5.4d 3P* → 4p5.(2P*<1/2>).5p 2[1/2] | Measured | NIST | |
| 380.1896 nm | 2500 | Rb II | emission | 4p5.(2P*<1/2>).5s 2[1/2]* → 4p5.(2P*<1/2>).5p 2[1/2] | Measured | NIST | |
| 437.7123 nm | 2500 | Rb II | emission | 4p5.(2P*<3/2>).5p 2[5/2] → 4p5.(2P*<3/2>).6s 2[3/2]* | Measured | NIST | |
| 402.9485 nm | 1700 | Rb II | emission | 4p5.(2P*<3/2>).5s 2[3/2]* → 4p5.(2P*<3/2>).5p 2[3/2] | Measured | NIST | |
| 429.3971 nm | 1500 | Rb II | emission | 4p5.(2P*<3/2>).5s 2[3/2]* → 4p5.(2P*<3/2>).5p 2[3/2] | Measured | NIST | |
| 382.66591 nm | 1000 | Rb II | emission | 4p5.(2P*<3/2>).5p 2[3/2] → 4p5.(2P*<3/2>).5d 2[3/2]* | Measured | NIST | |
| 420.18053 nm | 1000 | Rb I | emission | 4p6.5s 2S → 4p6.6p 2P* | Measured | NIST | |
| 434.6961 nm | 1000 | Rb II | emission | 4p5.(2P*<3/2>).5p 2[5/2] → 4p5.(2P*<3/2>).6s 2[3/2]* | Measured | NIST | |
| 446.9475 nm | 1000 | Rb II | emission | 4p5.(2P*<1/2>).5p 2[3/2] → 4p5.(2P*<1/2>).6s 2[1/2]* | Measured | NIST | |
| 473.0454 nm | 1000 | Rb II | emission | 4p5.4d 3P* → 4p5.(2P*<1/2>).5p 2[1/2] | Measured | NIST | |
| 475.5304 nm | 1000 | Rb II | emission | 4p5.(2P*<3/2>).5p 2[3/2] → 4p5.(2P*<3/2>).6s 2[3/2]* | Measured | NIST | |
| 655.5619 nm | 1000 | Rb II | emission | 4p5.4d 3P* → 4p5.(2P*<3/2>).5p 2[3/2] | Measured | NIST | |
| 451.90262 nm | 700 | Rb II | emission | 4p5.4d 1P* → 4p5.(2P*<3/2>).4f 2[3/2] | Measured | NIST | |
| 392.22011 nm | 500 | Rb II | emission | 4p5.(2P*<3/2>).5p 2[3/2] → 4p5.(2P*<3/2>).5d 2[1/2]* | Measured | NIST | |
| 421.5539 nm | 500 | Rb I | emission | 4p6.5s 2S → 4p6.6p 2P* | Measured | NIST | |
| 426.6584 nm | 500 | Rb II | emission | 4p5.(2P*<3/2>).5p 2[5/2] → 4p5.(2P*<3/2>).6s 2[3/2]* | Measured | NIST | |
| 465.9284 nm | 500 | Rb II | emission | 4p5.(2P*<3/2>).5p 2[3/2] → 4p5.(2P*<3/2>).6s 2[3/2]* | Measured | NIST | |
| 551.2542 nm | 500 | Rb II | emission | 4p5.4d 3F* → 4p5.(2P*<1/2>).5p 2[3/2] | Measured | NIST | |
| 386.07454 nm | 450 | Rb II | emission | 4p5.(2P*<3/2>).5p 2[1/2] → 4p5.(2P*<3/2>).6s 2[3/2]* | Measured | NIST | |
| 454.0732 nm | 400 | Rb II | emission | 4p5.(2P*<3/2>).5p 2[3/2] → 4p5.(2P*<3/2>).6s 2[3/2]* | Measured | NIST | |
| 444.00924 nm | 300 | Rb II | emission | 4p5.4d 1P* → 4p5.(2P*<3/2>).4f 2[5/2] | Measured | NIST | |
| 516.4575 nm | 300 | Rb II | emission | 4p5.(2P*<1/2>).5s 2[1/2]* → 4p5.(2P*<3/2>).5p 2[3/2] | Measured | NIST | |
| 626.94 nm | 300 | Rb II | emission | 4p5.(2P*<3/2>).4f 2[9/2] → 4p5.(2P*<3/2>).6g 2[11/2]* | Measured | NIST | |
| 390.7292 nm | 250 | Rb II | emission | 4p5.(2P*<3/2>).5p 2[3/2] → 4p5.(2P*<3/2>).5d 2[1/2]* | Measured | NIST | |
| 542.244 nm | 250 | Rb II | emission | 4p5.4d 1P* → 4p5.(2P*<3/2>).6p 2[3/2] | Measured | NIST | |
| 527.0514 nm | 200 | Rb II | emission | 4p5.(2P*<3/2>).5p 2[1/2] → 4p5.(2P*<3/2>).6s 2[3/2]* | Measured | NIST | |
| 573.9645 nm | 200 | Rb II | emission | 4p5.(2P*<3/2>).5d 2[7/2]* → 4p5.(2P*<3/2>).5f 2[9/2] | Measured | NIST | |
| 613.5268 nm | 200 | Rb II | emission | 4p5.(2P*<3/2>).5d 2[5/2]* → 4p5.(2P*<3/2>).5f 2[7/2] | Measured | NIST | |
| 383.78512 nm | 175 | Rb II | emission | 4p5.(2P*<3/2>).5p 2[3/2] → 4p5.(2P*<3/2>).5d 2[1/2]* | Measured | NIST | |
| 740.8171 nm | 150 | Rb I | emission | 4p6.5p 2P* → 4p6.7s 2S | Measured | NIST | |
| 550.0635 nm | 100 | Rb II | emission | 4p5.(2P*<3/2>).6p 2[5/2] → 4p5.(2P*<3/2>).7d 2[7/2]* | Measured | NIST | |
| 627.5697 nm | 100 | Rb II | emission | 4p5.(2P*<3/2>).4f 2[9/2] → 4p5.(2P*<3/2>).6g 2[11/2]* | Measured | NIST | |
| 451.9884 nm | 75 | Rb II | emission | 4p5.(2P*<3/2>).5d 2[5/2]* → 4p5.(2P*<3/2>).6f 2[7/2] | Measured | NIST | |
| 459.989 nm | 75 | Rb II | emission | 4p5.(2P*<3/2>).5d 2[5/2]* → 4p5.(2P*<3/2>).6f 2[7/2] | Measured | NIST | |
| 543.1528 nm | 75 | Rb I | emission | 4p6.5p 2P* → 4p6.8d 2D | Measured | NIST | |
| 589.308 nm | 75 | Rb II | emission | 4p5.(2P*<3/2>).5d 2[7/2]* → 4p5.(2P*<3/2>).5f 2[9/2] | Measured | NIST | |
| 607.0751 nm | 75 | Rb I | emission | 4p6.5p 2P* → 4p6.8s 2S | Measured | NIST | |
| 614.0319 nm | 75 | Rb II | emission | 4p5.4d 3F* → 4p5.(2P*<1/2>).5p 2[3/2] | Measured | NIST | |
| 572.4125 nm | 60 | Rb I | emission | 4p6.5p 2P* → 4p6.7d 2D | Measured | NIST |
Extended Properties
Covalent Radii (Extended)
- Covalent radius (Pyykkö)
- 210 pm
- Covalent radius (Pyykkö, double)
- 202 pm
- Covalent radius (Bragg)
- 225 pm
Van der Waals Radii
- Truhlar
- 303 pm
- Batsanov
- 290 pm
- Alvarez
- 321 pm
- UFF
- 411.4 pm
- MM3
- 325 pm
Atomic & Metallic Radii
- Atomic radius (Rahm)
- 240 pm
- Metallic radius (C12)
- 248 pm
Numbering Scales
- Mendeleev
- 4
- Pettifor
- 9
- Glawe
- 9
Electronegativity Scales
- Ghosh
- 0
- Miedema
- 2
- Gunnarsson–Lundqvist
- 2
- Robles–Bartolotti
- 1
Polarizability & Dispersion
- Dipole polarizability
- 319.8 a.u.
- Dipole polarizability (unc.)
- 0.3 a.u.
- C₆
- 4769 Ha·Bohr6
- C₆ (Gould–Bučko)
- 4660 Ha·Bohr6
Miedema Parameters
- Miedema molar volume
- 56.07 cm3/mol
- Miedema electron density
- 0
Phase Transitions & Allotropes
| Melting point | 312.45 K |
| Boiling point | 961.15 K |
| Critical point (temperature) | 2093.15 K |
| Critical point (pressure) | 16 MPa |
| Triple point (temperature) | 312.41 K |
Oxidation State Categories
Advanced Reference Data
Screening Constants (9)
| n | Orbital | σ |
|---|---|---|
| 1 | s | 0.7922 |
| 2 | p | 3.9612 |
| 2 | s | 9.8432 |
| 3 | d | 15.3208 |
| 3 | p | 15.6967 |
| 3 | s | 15.1573 |
| 4 | p | 26.1192 |
| 4 | s | 24.612 |
| 5 | s | 32.0155 |
Crystal Radii Detail (8)
| Charge | CN | Spin | rcrystal (pm) | Origin |
|---|---|---|---|---|
| 1 | VI | 166 | ||
| 1 | VII | 170 | ||
| 1 | VIII | 175 | ||
| 1 | IX | 177 | estimated, | |
| 1 | X | 180 | ||
| 1 | XI | 183 | ||
| 1 | XII | 186 | ||
| 1 | XIV | 197 |
Isotope Decay Modes (61)
| Isotope | Mode | Intensity |
|---|---|---|
| 71 | p | — |
| 72 | p | — |
| 73 | B+ | — |
| 73 | p | 100% |
| 74 | B+ | 100% |
| 74 | B+p | — |
| 75 | B+ | 100% |
| 76 | B+ | 100% |
| 76 | B+A | 3.8% |
| 77 | B+ | 100% |
X‑ray Scattering Factors (508)
| Energy (eV) | f₁ | f₂ |
|---|---|---|
| 10 | — | 0.06968 |
| 10.1617 | — | 0.07104 |
| 10.3261 | — | 0.07253 |
| 10.4931 | — | 0.07441 |
| 10.6628 | — | 0.07635 |
| 10.8353 | — | 0.07833 |
| 11.0106 | — | 0.08037 |
| 11.1886 | — | 0.083 |
| 11.3696 | — | 0.08599 |
| 11.5535 | — | 0.0891 |
Additional Data
Estimated Crustal Abundance
The estimated element abundance in the earth's crust.
9.0×101 milligrams per kilogram
References (1)
- [5] Rubidium https://education.jlab.org/itselemental/ele037.html
Estimated Oceanic Abundance
The estimated element abundance in the earth's oceans.
1.2×10-1 milligrams per liter
References (1)
- [5] Rubidium https://education.jlab.org/itselemental/ele037.html
Sources
Sources of this element.
The element is much more abundant than was thought several years ago. It is now considered to be the 16th most abundant element in the earth's crust. Rubidium occurs in pollucite, leucite, and zinnwaldite, which contains traces up to 1%, in the form of the oxide. It is found in lepidolite to the extent of about 1.5%, and is recovered commercially from this source. Potassium minerals, such as those found at Searles Lake, California, and potassium chloride recovered from the brines in Michigan also contain the element and are commercial sources. It is also found along with cesium in the extensive deposits of pollucite at Bernic Lake, Manitoba.
References (1)
- [6] Rubidium https://periodic.lanl.gov/37.shtml
References
(9)
Data deposited in or computed by PubChem
The half-life and atomic mass data was provided by the Atomic Mass Data Center at the International Atomic Energy Agency.
Element data are cited from the Atomic weights of the elements (an IUPAC Technical Report). The IUPAC periodic table of elements can be found at https://iupac.org/what-we-do/periodic-table-of-elements/. Additional information can be found within IUPAC publication doi:10.1515/pac-2015-0703 Copyright © 2020 International Union of Pure and Applied Chemistry.
The information are cited from Pure Appl. Chem. 2018; 90(12): 1833-2092, https://doi.org/10.1515/pac-2015-0703.
Thomas Jefferson National Accelerator Facility (Jefferson Lab) is one of 17 national laboratories funded by the U.S. Department of Energy. The lab's primary mission is to conduct basic research of the atom's nucleus using the lab's unique particle accelerator, known as the Continuous Electron Beam Accelerator Facility (CEBAF). For more information visit https://www.jlab.org/
The periodic table at the LANL (Los Alamos National Laboratory) contains basic element information together with the history, source, properties, use, handling and more. The provenance data may be found from the link under the source name.
The periodic table contains NIST's critically-evaluated data on atomic properties of the elements. The provenance data that include data for atomic spectroscopy, X-ray and gamma ray, radiation dosimetry, nuclear physics, and condensed matter physics may be found from the link under the source name. Ref: https://www.nist.gov/pml/atomic-spectra-database
This section provides all form of data related to element Rubidium.
The element property data was retrieved from publications.