Rubidium

properties
[ Kr ] 5 s 1 37 Rb Periodic table
General
Name , symbol , atomic number	Rubidium, Rb, 37
Element category	Alkali metals
Group , period , block	1 , 5 , p
Appearance	silvery white
CAS number	7440-17-7
EC number	231-126-6
ECHA InfoCard	100.028.296
Mass fraction of the earth's envelope	29 ppm
Atomic
Atomic mass	85.4678 (3) et al
Atomic radius (calculated)	235 (265) pm
Covalent radius	220 pm
Van der Waals radius	303 pm
Electron configuration	[ Kr ] 5 s 1
1. Ionization energy	4th.177 128 0 (12) eV ≈ 403.03 kJ / mol
2. Ionization energy	27.28954 (6) eV ≈ 2 633.04 kJ / mol
3. Ionization energy	39.247 (3) eV ≈ 3 786.8 kJ / mol
4. Ionization energy	52.20 (25) eV ≈ 5 037 kJ / mol
5. Ionization energy	68.44 (15) eV ≈ 6 603 kJ / mol
Physically
Physical state	firmly
Crystal structure	body-centered cubic
density	1.532 g / cm 3 (20 ° C )
Mohs hardness	0.3
magnetism	paramagnetic ( Χ m = 3.8 10 −6 )
Melting point	312.46 K (39.31 ° C)
boiling point	961.2 K (688 ° C)
Molar volume	55.76 10 −6 m 3 mol −1
Heat of evaporation	69 kJ / mol
Heat of fusion	2.19 kJ mol −1
Speed ​​of sound	1300 m s −1 at 293.15 K.
Work function	2.16 eV
Electric conductivity	7.52 · 10 6 A · V −1 · m −1
Thermal conductivity	58 W m −1 K −1
Chemically
Oxidation states	−1, +1
Normal potential	−2.924 V (Rb + + e - → Rb)
Electronegativity	0.82 ( Pauling scale )
Isotopes
isotope NH t 1/2 ZA ZE (M eV ) ZP 83 Rb {syn.} 86.2 d ε 0.910 83 kr 84 Rb {syn.} 32.77 d ε 2,681 84 kr β - 0.894 84 Sr 85 Rb 72.168  % Stable 86 Rb {syn.} 18,631 d β - 1.775 86 Sr 87 Rb 27.835% 4.81 x 10 10 a . β - 0.283 87 Sr 88 Rb {syn.} 17.78 min β - 5.316 88 Sr 89 Rb {syn.} 15.15 min β - 4,501 89 Sr
For other isotopes see list of isotopes
NMR properties
Spin quantum number I γ in rad · T −1 · s −1 E r  ( 1 H) f L at B = 4.7 T in MHz 85 Rb 5/2 2.583 · 10 7 0.0105 19.3 87 Rb 3/2 8,753 · 10 7 0.175 65.4
safety instructions
GHS labeling of hazardous substances danger H and P phrases H: 260-314 EUH: 014 P: 223-231 + 232-280-305 + 351 + 338-370 + 378-422
As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions .

Rubidium (from Latin rubidus 'deep red'; because of two characteristic red spectral lines ) is a chemical element with the element symbol Rb and the ordinal number 37. In the periodic table it is in the 1st main group , or the 1st  IUPAC group, and is one of the Alkali metals . The soft, silvery white shiny metal ignites spontaneously when exposed to air.

history

Rubidium was discovered spectroscopically in 1861 by Robert Wilhelm Bunsen and Gustav Kirchhoff as a small (<1%) component of lepidolite from Saxony and Moravia, and as a component in the mineral water of the newly developed Maxquelle in Bad Dürkheim . Bunsen succeeded in precipitating rubidium salts both from the digested lepidolite and from mineral water brine and to separate it from other alkali metal salts. For this purpose, Bunsen processed 150 kg of digested lepidolite in order to isolate a few grams of RbCl , and 44200 liters of Dürkheim spring water for 9 g of RbCl.

Occurrence

Rubidium belongs to the group of incompatible elements and usually occurs together with these in high concentrations. The element occurs in small concentrations in some minerals such as leucite , pollucite and zinnwaldite . Lepidolite contains up to 1.5% rubidium. Only in recent years, independent rubidium minerals were discovered how rubicline (a rubidium-aluminum silicate) and Voloshinit and rubidium Ramanit (Rubidiumpentaborat tetrahydrate).

presentation

In the laboratory, small amounts of pure rubidium are produced by reducing the chromate or dichromate using zirconium :

${\displaystyle {\ce {2 Rb2CrO4 + Zr -> 4 Rb + Zr(CrO4)2}}}$

${\displaystyle {\ce {2 Rb2Cr2O7 + Zr -> 4 Rb + Zr(Cr2O7)2}}}$

or the thermal decomposition of rubidium azide :

${\displaystyle {\ce {2 RbN3 -> 2 Rb + 3 N2}}}$

and subsequent distillation in a high vacuum .

properties

The flame color of rubidium

1 g rubidium in an ampoule

Like the other alkali metals, rubidium is fragile and oxidizes in air. It reacts extremely violently with water to form rubidium hydroxide and hydrogen , which usually ignite in the air. It forms an amalgam with mercury ; it can be alloyed with the metals gold , cesium , sodium and potassium . Rubidium compounds color flames dark red (hence the name of the element). Rubidium is a powerful reducing agent . Metallic rubidium can be produced by reducing rubidium chloride with calcium in a vacuum .

Isotopes

Of the two naturally occurring isotopes only is ⁸⁵ Rb stable ⁸⁷ Rb is a beta emitter and decays to ⁸⁷ Sr . With an extremely long half-life of around 48 billion years, its radioactivity is very low. The ratio of Rb and Sr isotopes in rocks is used for radiometric dating .

use

Rubidium and its compounds have only a small range of applications and are mainly used in research and development. Possible uses exist as:

• Getter metal in vacuum tubes ,
• Cathode coating,
• Tracer in PET - Perfusion studies of the myocardium ,
• Rubidium clocks as time normals ( atomic clock )
• Demonstration of laser cooling , since cheap laser diodes are available for the relevant wavelengths (thus comparatively easy production of a Bose-Einstein condensate ).
• In fireworks to create purple fire

proof

Its red-violet flame color can be used to detect rubidium . The spectroscope shows a clear emission line at 780.0 nm. Quantitatively, this can be used in flame photometry to determine traces of rubidium. In polarography , rubidium shows a reversible cathodic step at −2.118 V (versus SCE ). Quaternary ammonium compounds (here for example 0.1 M tetramethylammonium hydroxide ) must be used as the base electrolyte because other alkali or alkaline earth metal ions have very similar half-wave potentials.

Another qualitative proof is the formation of a sparingly soluble triple salt in a weakly acidic solution with sodium, bismuth and nitrite ions, which produce a yellow-colored precipitate of the composition , the crystals of which have an octahedral shape. The detection limit is 0.5 mg rubidium. This can be increased by using silver ions instead of sodium ions, but cesium provides a similar reaction. ${\displaystyle {\ce {RbNaBi(NO2)6}}}$

physiology

Rubidium is probably not essential for plants; in animals, it seems to be necessary for normal pregnancy . The rubidium requirement of humans is likely to be less than 100 µg per day. With the usual mixed diet, it comes to around 1.7 mg per day. A rubidium deficiency is just as unlikely with this offer as a nutritive rubidium contamination. Tea and coffee - Arabica coffee has the highest rubidium content found in food (Arabica beans: 25.5–182 mg / kg dry matter) - adults provide an average of 40% of the amount of rubidium consumed. Rubidium acts in the central nervous system and influences the concentration of neurotransmitters there ; the use of rubidium as an antidepressant agent is being discussed. A rubidium deficiency can be present in dialysis patients .

safety instructions

Rubidium is self-igniting and reacts extremely violently with water. For safety reasons, rubidium should be stored in dry mineral oil , in a vacuum or in an inert gas atmosphere.

links

Oxides and hydroxides

• Rubidium oxide Rb ₂ O
• Rubidium peroxide Rb ₂ O ₂
• Rubidium Hyperoxide RbO ₂
• Rubidium ozonide RbO ₃
• Rubidium hydroxide RbOH

Halides

• Rubidium Fluoride RbF
• Rubidium chloride RbCl
• Rubidium bromide RbBr
• Rubidium iodide RbI
• Rubidium triiodide RbI ₃

Other connections

• Rubidium Nitrate RbNO ₃
• Rubidium sulfate Rb ₂ SO ₄
• Rubidium hydrogen sulfate RbHSO ₄

• Rubidium Chlorate RbClO ₃
• Rubidium perchlorate RbClO ₄
• Rubidium bromate RbBrO ₃
• Rubidium iodate RbIO ₃
• Rubidium Periodate RbIO ₄

• Rubidium chromate Rb ₂ CrO ₄
• Rubidium dichromate Rb ₂ Cr ₂ O ₇
• Rubidium hydrogen carbonate RbHCO ₃
• Rubidium Dithionate Rb ₂ S ₂ O ₆
• Rubidium acetate CH ₃ COORb
• Rubidium formate HCOORb

• Rubidium hydride RbH
• Rubidium amide RbNH ₂
• Rubidium Azide RbN ₃
• Rubidium Selenide Rb ₂ Se

Individual evidence

1. ↑ ^{a b} Harry H. Binder: Lexicon of the chemical elements. S. Hirzel Verlag, Stuttgart 1999, ISBN 3-7776-0736-3 .
2. ↑ The values ​​for the properties (info box) are taken from www.webelements.com (Rubidium) , unless otherwise stated .
3. ↑ CIAAW, Standard Atomic Weights Revised 2013 .
4. ↑ Manjeera Mantina, Adam C. Chamberlin, Rosendo Valero, Christopher J. Cramer, Donald G. Truhlar: Consistent van der Waals Radii for the Whole Main Group. In: J. Phys. Chem. A. 113, 2009, pp. 5806-5812, doi: 10.1021 / jp8111556 .
5. ↑ ^{a b c d e} Entry on rubidium in Kramida, A., Ralchenko, Yu., Reader, J. and NIST ASD Team (2019): NIST Atomic Spectra Database (ver. 5.7.1) . Ed .: NIST , Gaithersburg, MD. doi : 10.18434 / T4W30F ( https://physics.nist.gov/asd ). Retrieved June 11, 2020.
6. ↑ ^{a b c d e} Entry on rubidium at WebElements, https://www.webelements.com , accessed on June 11, 2020.
7. ^ ^{A b} N. N. Greenwood, A. Earnshaw: Chemistry of the elements. 1st edition. VCH, Weinheim 1988, ISBN 3-527-26169-9 , p. 97.
8. ↑ Robert C. Weast (Ed.): CRC Handbook of Chemistry and Physics . CRC (Chemical Rubber Publishing Company), Boca Raton 1990, ISBN 0-8493-0470-9 , pp. E-129 to E-145. Values ​​there are based on g / mol and given in cgs units. The value specified here is the SI value calculated from it, without a unit of measure.
9. ↑ ^{a b} Yiming Zhang, Julian RG Evans, Shoufeng Yang: Corrected Values ​​for Boiling Points and Enthalpies of Vaporization of Elements in Handbooks. In: Journal of Chemical & Engineering Data . 56, 2011, pp. 328-337, doi: 10.1021 / je1011086 .
10. ↑ Ludwig Bergmann, Clemens Schaefer, Rainer Kassing: Textbook of Experimental Physics . Volume 6: Solids. 2nd Edition. Walter de Gruyter, 2005, ISBN 3-11-017485-5 , p. 361.
11. ^ Decay Radiation Results. In: Chart of Nuclides database. National Nuclear Data Center, accessed January 24, 2012 . 
12. ↑ ^{a b} Entry on Rubidium in the GESTIS substance database of the IFA , accessed on April 30, 2017(JavaScript required) .
13. ^ ^{A b} Gustav Kirchhoff, Robert Bunsen: Chemical analysis through spectral observations . Second treatise. In: Johann Christian Poggendorff (Ed.): Annals of Physics and Chemistry . 189 (Pogg. Ann. 113), no. 7 . Johann Ambrosius Barth, Leipzig 1861, p. 337–381 , doi : 10.1002 / andp.18611890702 , bibcode : 1861AnP ... 189..337K ( online at Gallica , Bibliothèque nationale de France).
14. ↑ Georg Brauer: Free alkali metals . In: Handbook of Preparative Inorganic Chemistry . Ferdinand Enke Verlag, Stuttgart 1954, p. 724 ff .
15. ↑ G. Kirchhoff, R. Bunsen: Chemical analysis through spectral observations . In: Annals of Physics and Chemistry . tape 189 , no. 7 , 1861, p. 337–381 , doi : 10.1002 / andp.18611890702 , bibcode : 1861AnP ... 189..337K .
16. ↑ J. Heyrovský , J. Kuta: Basics of polarography. Akademie-Verlag, Berlin 1965, p. 515.
17. ^ R. Fresenius, G. Jander: Rubidium - precipitation as rubidium-sodium-bismuth nitrite with sodium-bismuth nitrite . In: Handbuch der Analytischen Chemie, Part Two: Qualitative Verification Methods, Volume 1a: Elements of the first main group (including ammonium) . Springer-Verlag, Berlin 1944, p. 155-156 .
18. ↑ Andrea Illy, Rinantonio Viani: Espresso Coffee: The Science of Quality. Elsevier Academic Press, 2005, ISBN 0-12-370371-9 , p. 150.
19. ↑ M. Krachler, GH Wirnsberger: Long-term changes of plasma trace element Concentrations in chronic hemodialysis patients. In: Blood Purif. 18 (2), 2000, pp. 138-143, PMID 10838473 .
20. ^ HL Meltzer, RM Taylor, SR Platman, RR Fieve: Rubidium: A potential modifier of effect and behavior. In: Nature . 223, 1969, pp. 321-322, PMID 4978331 .
21. ↑ C. Canavese, E. DeCostanzi, L. Branciforte and others: Rubidium deficiency in dialysis patients. In: J Nephrol. 14 (3), 2001, pp. 169-175, PMID 11439740 .

Web links

Wiktionary: Rubidium  - explanations of meanings, word origins, synonyms, translations

Commons : Rubidium  - collection of images, videos and audio files