Editing Rhenium (section)

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'''Rhenium''' is a [[chemical element]]; it has [[Symbol (chemistry)|symbol]] '''Re''' and [[atomic number]] 75. It is a silvery-gray, heavy, third-row [[transition metal]] in [[group 7 element|group 7]] of the [[periodic table]]. With an estimated average concentration of 1 [[parts-per notation|part per billion]] (ppb), rhenium is one of the rarest elements in the [[Earth's crust]]. It has one of the highest melting and boiling points of any element. It resembles [[manganese]] and [[technetium]] chemically and is mainly obtained as a [[by-product]] of the extraction and refinement of [[molybdenum]] and [[copper]] ores. It shows in its compounds a wide variety of [[oxidation state]]s ranging from −1 to +7.

Rhenium was originally discovered in 1908 by [[Masataka Ogawa]], but he mistakenly assigned it as element 43 (now known as [[technetium]]) rather than element 75 and named it ''nipponium''. It was rediscovered in 1925 by [[Walter Noddack]], [[Ida Noddack|Ida Tacke]] and [[Otto Berg (scientist)|Otto Berg]],<ref>{{Cite journal |date=1925-06-01 |title=Die Ekamangane |url=https://doi.org/10.1007/BF01558746 |journal=Naturwissenschaften |language=de |volume=13 |issue=26 |pages=567–574 |doi=10.1007/BF01558746 |bibcode=1925NW.....13..567. |s2cid=32974087 |issn=1432-1904|url-access=subscription }}</ref> who gave it its present name. It was named after the river [[Rhine]] in Europe, from which the earliest samples had been obtained and worked commercially.<ref>{{cite web|title=From Hydrogen to Darmstadtium & More|page=144|url=https://books.google.com/books?id=YWkvAQAAIAAJ|publisher=American Chemical Society|date=2003}}</ref>

[[Nickel]]-based [[superalloy]]s of rhenium are used in combustion chambers, turbine blades, and exhaust nozzles of [[jet engine]]s. These alloys contain up to 6% rhenium, making jet engine construction the largest single use for the element. The second-most important use is as a [[Catalysis|catalyst]]: it is an excellent catalyst for [[hydrogenation]] and isomerization, and is used for example in [[catalytic reforming]] of naphtha for use in gasoline (rheniforming process). Because of the low availability relative to demand, rhenium is expensive, with price reaching an all-time high in 2008–09 of US$10,600 per [[kilogram]] (US$4,800 per pound). As of 2018, its price had dropped to US$2,844 per [[kilogram]] (US$1,290 per pound) due to increased recycling and a drop in demand for rhenium catalysts.<ref>{{Cite web|url=https://apps.catalysts.basf.com/apps/eibprices/mp/YearlyCharts.aspx|title=BASF Catalysts - Metal Prices|website=apps.catalysts.basf.com|access-date=2018-04-11|archive-date=2021-04-12|archive-url=https://web.archive.org/web/20210412125504/https://apps.catalysts.basf.com/apps/eibprices/mp/YearlyCharts.aspx|url-status=dead}}</ref>