Rubidium: Difference between revisions

{{distinguish|Rutheniumruthenium}}

'''Rubidium''' is a [[chemical element]]; it has [[Symbol (chemistry)|symbol]] '''Rb''' and [[atomic number]] 37. It is a very soft, whitish-grey solid in the [[alkali metal]] group, similar to [[potassium]] and [[caesium]].<ref>{{Ullmann |doi=10.1002/14356007.a23_473.pub2 |title=Rubidium and Rubidium Compounds |year=2010 |last1=Lenk |first1=Winfried |last2=Prinz |first2=Horst |last3=Steinmetz |first3=Anja |isbn=978-3527306732 }}</ref> Rubidium is the first [[alkali metal]] in the group to have a density higher than [[Properties of water|water]]. On Earth, natural rubidium comprises two [[isotope]]s: 72% is a stable isotope ⁸⁵Rb, and 28% is slightly [[radioactive]] ⁸⁷Rb, with a [[half-life]] of 48.8 billion years—more than three times as long as the estimated [[age of the universe]].

German chemists [[Robert Bunsen]] and [[Gustav Kirchhoff]] discovered rubidium in 1861 by the newly developed technique, [[Atomic emission spectroscopy#Flame emission spectroscopy|flame spectroscopy]]. The name comes from the [[Latin]] word {{lang|la|rubidus}}, meaning deep red, the color of its emission spectrum. Rubidium's compounds have various chemical and electronic applications. Rubidium metal is easily vaporized and has a convenient spectral absorption range, making it a frequent target for [[laser]] manipulation of [[atom]]s.<ref>{{Cite web |title=Rubidium (Rb) {{!}} AMERICAN ELEMENTS ® |url=https://www.americanelements.com/rb.htm |access-date=2024-03-27 |website=American Elements: The Materials Science Company |language=en}}</ref> Rubidium is not a known nutrient for any [[organism|living organisms]]. However, rubidium [[ion]]s have similar properties and the same charge as potassium ions, and are actively taken up and treated by [[animal cell]]s in similar ways.

Rubidium has a very low [[ionization energy]] of only 406&nbsp;kJ/mol.<ref>{{cite book | url = https://books.google.com/books?id=ZOm8L9oCwLMC&pg=PA259 | page =259 | title = Principles of Chemistry: The Molecular Science | isbn = 978-0-495-39079-4 | author1 = Moore, John W | author2 = Stanitski, Conrad L | author3 = Jurs, Peter C | date = 2009| publisher =Cengage Learning }}</ref> Rubidium and potassium show a very similar purple color in the [[flame test]], and distinguishing the two elements requires more sophisticated analysis, such as spectroscopy.{{citation needed|date=December 2021}}<ref>{{Cite journal |last1=Ahrens |first1=L. H |last2=Pinson |first2=W. H |last3=Kearns |first3=Makgaret M |date=1952-01-01 |title=Association of rubidium and potassium and their abundance in common igneous rocks and meteorites |url=https://dx.doi.org/10.1016/0016-7037%2852%2990017-3 |journal=Geochimica et Cosmochimica Acta |volume=2 |issue=4 |pages=229–242 |doi=10.1016/0016-7037(52)90017-3 |bibcode=1952GeCoA...2..229A |issn=0016-7037}}</ref><!-- As a symmetrical effect of rubidium metal's high reactivity toward oxidation and tendency to subsequent formation of the rubidium cation Rb⁺, this cation, once formed, is very stable, and is normally unreactive toward further oxidative or reductive chemical reactions.{{citation needed|date=December 2010}}--><!--ionization energy 10.1103/PhysRevA.49.1646 --><!-- https://books.google.com/books?id=mDXzAAAAMAAJ&q=Rubidium+coordination&dq=Rubidium+coordination&hl=de&ei=5GB9Tc7pJ4f2sgax7ZTsBw&sa=X&oi=book_result&ct=result&resnum=1&ved=0CDIQ6AEwAA the coordination is at least six and even nine is possible 10.1007/BF00745739 or twelve http://scripts.iucr.org/cgi-bin/paper?a04757-->

Rubidium is not abundant, being one of 56 elements that combined make up 0.05% of the twentyEarth's crust; at roughly the 23rd <!--third verified in USGS ref -->[[Abundance of elements in Earth's crust|most abundant element in the Earth's crust]], roughlyit asis more abundant asthan [[zinc]] and rather more common thanor [[copper]].<ref name="USGS">{{cite web |url = http://pubs.usgs.gov/of/2003/of03-045/of03-045.pdf |publisher = United States Geological Survey |access-date = 2010-12-04 |title = Mineral Commodity Profile: Rubidium |first1 = William C. |last1 = Butterman |first2 = William E. |last2 = Brooks |first3 = Robert G. Jr. |last3 = Reese |date=2003}}</ref>{{rp|4}} It occurs naturally in the minerals [[leucite]], [[pollucite]], [[carnallite]], and [[zinnwaldite]], which contain as much as 1% rubidium [[oxide]]. [[Lepidolite]] contains between 0.3% and 3.5% rubidium, and is the commercial source of the element.<ref>{{Cite journal |title =Trace element chemistry of lithium-rich micas from rare-element granitic pegmatites |volume = 55

[[Seawater]] contains an average of 125&nbsp;µgμg/L of rubidium compared to the much higher value for potassium of 408&nbsp;mg/L and the much lower value of 0.3&nbsp;µgμg/L for caesium.<ref>{{cite journal |last1 = Bolter |first1 = E. |last2 = Turekian |first2 = K. |last3 = Schutz |first3 = D. |title = The distribution of rubidium, cesium and barium in the oceans |journal = Geochimica et Cosmochimica Acta |volume = 28 |issue = 9 |pages = 1459 |date = 1964 |doi = 10.1016/0016-7037(64)90161-9 |bibcode = 1964GeCoA..28.1459B }}</ref> Rubidium is the 18th most abundant element in seawater.<ref>{{Cite book |last1=Hart |first1=William A. Hart|url=https://doi.org/10.1016/C2013-0-05695-2 |title=The Chemistry of Lithium, Sodium, Potassium, Rubidium, Caesium,Cesium and Francium |last2=Beumel Jr. |first2=O.F . |last3=Whaley |first3=Thomas P. |date=1973 |publisher=Elsevier |isbn=978-0-08-018799-0 |page=371 |doi=10.1016/c2013-0-05695-2}}</ref>

The resonant element in [[atomic clock]]s utilizes the [[hyperfine structure]] of rubidium's energy levels, and rubidium is useful for high-precision timing. It is used as the main component of secondary frequency references (rubidium oscillators) in cell site transmitters and other electronic transmitting, networking, and test equipment. These [[rubidium standard]]s are often used with [[Global Positioning System|GPSGNSS]] to produce a "primary frequency standard" that has greater accuracy and is less expensive than caesium standards.<ref>{{cite book |chapter-url = https://books.google.com/books?id=jmfkJYdEANEC&pg=PA32 |page = 32 |chapter = GPS |title = Measurement, control, and communication using IEEE 1588 |isbn = 978-1-84628-250-8 |author1 = Eidson, John C |date = 2006-04-11|publisher = Springer }}</ref><ref name="Clock">{{cite book |chapter-url = https://books.google.com/books?id=ttYt5bZqX0AC&pg=PA300 |page = 300 |chapter = Rubidium and crystal oscillators |title = Data network engineering |isbn = 978-0-7923-8594-3 |author1 = King, Tim |author2 = Newson, Dave |date = 1999-07-31|publisher = Springer }}</ref> Such rubidium standards are often mass-produced for the [[telecommunication]] industry.<ref>{{cite book |chapter-url = https://books.google.com/books?id=LesrjSVQMPQC&pg=PA72 |chapter = Rubidium Vapor Cell |title = Advances in electronics and electron physics |isbn = 978-0-12-014644-4 |author1 = Marton, L. |date = 1977-01-01|publisher = Academic Press }}</ref>