Editing Per Teodor Cleve

{{Short description|Swedish chemist who discovered holmium and thulium (1840–1905)}}
{{Use dmy dates|date=March 2014}}
{{Infobox scientist
| name              = 
| image             = Per Teodor Cleve c1885.jpg
| caption           = Per Teodor Cleve, c. 1880–1890
| image_size        = 
| alt               = 
| birth_name        = 
| birth_date        = 10 February 1840
| birth_place       = [[Stockholm]], Sweden
| death_date        = {{death date and age|1905|6|18|1840|2|10|df=y}}
| death_place       = [[Uppsala]], Sweden
| residence         = 
| citizenship       = 
| nationality       = Swedish
| ethnicity         = 
| fields            = [[Chemistry]], [[geology]]
| workplaces        = 
| alma_mater        = [[Stockholms Lyceum]] (1858)<br>[[Uppsala University]] (1863)
| doctoral_advisor  = 
| academic_advisors = 
| doctoral_students = 
| notable_students  = 
| known_for         = discovery of [[holmium]] and [[thulium]]
| author_abbrev_bot = 
| author_abbrev_zoo = 
| influences        = 
| influenced        = 
| awards            = [[Davy Medal]] <small>(1894)</small>
| religion          = 
| signature         = <!--(filename only)-->
| signature_alt     = 
| footnotes         = 
| spouse            = {{marriage|[[: se : Alma Cleve|Carolina Alma Öhbom]]|1874|<!-- Omission per Template:Marriage instructions -->}}
| children          = [[Astrid Cleve]]<br/>[[: se : Agnes Cleve-Jonand|Agnes Cleve-Jonand]]<br/>[[: se : Célie Brunius|Célie Brunius]]
}}

'''Per Teodor Cleve''' (10 February 1840 – 18 June 1905) was a Swedish [[chemist]], [[biologist]], [[mineralogist]] and [[oceanographer]]. He is best known for his discovery of the chemical elements [[holmium]] and [[thulium]].<ref name = "britannica">{{Cite encyclopedia | encyclopedia=Encyclopædia Britannica |url = http://www.britannica.com/EBchecked/topic/121389/Per-Teodor-Cleve|title = Per Teodor Cleve|accessdate = 13 March 2014}}</ref><ref name = "encyclopedia"/>

Born in Stockholm in 1840, Cleve earned his [[BSc]] and [[PhD]] from [[Uppsala University]] in 1863 and 1868, respectively. After receiving his PhD, he became an assistant professor of chemistry at the university. He later became professor of general and agricultural chemistry. In 1874 he theorised that [[didymium]] was in fact two elements; this theory was confirmed in 1885 when [[Carl Auer von Welsbach]] discovered [[neodymium]] and [[praseodymium]]. 

In 1879 Cleve discovered holmium and thulium.<ref name="Virginia"/> His other contributions to chemistry include the discovery of [[aminonaphthalenesulfonic acids]], also known as Cleve's acids. From 1890 on he focused on biological studies. He developed a method of determining the age and order of late glacial and postglacial [[Till|deposits]] from the types of [[diatom]] fossils in the deposits, and wrote a seminal text in the field of oceanography. He died in 1905 at age 65.

==Early life==
[[File:Per Teodor Cleve 1863.jpg|thumb|left|upright|Cleve in 1863]]
Cleve was born in [[Stockholm]], Sweden, as the thirteenth child of his father,<ref name = "britannica"/><ref name = "nndb"/> a merchant known as Fredrik Theodor Cleve.<ref name = "nndb"/><ref name = "collected"/> Cleve's ancestors on his father's side came from western Germany and settled in Sweden in the late 18th century.<ref name = "collected"/>

Cleve showed interest in [[natural science]] and [[natural history]] from an early age.<ref name = "collected"/> He attended the [[Stockholms Lyceum]] in 1858, studying chemistry and biology.<ref name="encyclopedia">{{Citation|author = Charles Scribner's Sons|url = http://www.encyclopedia.com/topic/Per_Teodor_Cleve.aspx|encyclopedia = encyclopedia.com|title = Cleve, Per Teodor|year = 2008|access-date = 13 March 2014|url-status = dead|archiveurl = https://web.archive.org/web/20140315045805/http://www.encyclopedia.com/topic/Per_Teodor_Cleve.aspx|archivedate = 15 March 2014|df = dmy-all}}</ref><ref name = "nndb"/> He gained a [[Bachelor of Science]] degree from the University of Uppsala in 1863 and a [[PhD]] from the same university in 1868.<ref name = "nndb"/>

==Career==
In 1860, aged 20, Cleve became [[assistant professor]] of [[mineralogy]] at the [[University of Uppsala]],<ref name = "encyclopedia2"/> and was appointed assistant professor of chemistry in 1868.<ref name = "britannica"/><ref name = "encyclopedia2"/> He also taught at the [[Royal Institute of Technology]] between 1870 and 1874, and eventually became professor of [[chemistry|general]] and [[agricultural chemistry]] at the University of Uppsala.<ref name = "britannica"/> He was the chair of chemistry at the University of Uppsala starting in 1874. He was also the president of the [[Nobel Committee for Chemistry]].<ref name = "acs">{{Citation|editor1=Ira Remsen |editor2=Charles August Rouillu |url = https://books.google.com/books?id=-38FAQAAIAAJ&pg=PA349|title = American Chemical Journal, Volume 34|year = 1905}}</ref>

Cleve's first work was ''Några ammoniakaliska chromföreningar'' (''Some compounds of ammonia and chromium'', 1861).<ref name = "encyclopedia"/><ref name = "encyclopedia2"/> He also wrote several more papers on complex compounds, including the [[platinum#compounds|compounds of platinum]].<ref name = "encyclopedia"/><ref name = "encyclopedia2"/> Additionally, Cleve synthesized several hundred complex platinum compounds.<ref name = "encyclopedia2"/>

Cleve visited a number of laboratories in England, France, Italy, and Switzerland in the 1860s.<ref name="encyclopedia2">{{Citation|author = Ole Bostrup|url = http://www.encyclopedia.com/topic/Per_Teodor_Cleve.aspx#2|title = Cleve, Per Theodor|year = 2004|encyclopedia = encyclopedia.com|access-date = 14 March 2014|url-status = dead|archiveurl = https://web.archive.org/web/20140315045805/http://www.encyclopedia.com/topic/Per_Teodor_Cleve.aspx#2|archivedate = 15 March 2014|df = dmy-all}}</ref> While in Paris, he visited the laboratory of [[Charles-Adolphe Wurtz]] and also made a number of friends there.<ref name = "encyclopedia2"/>

[[File:Per Teodor Cleve c1900.jpg|thumb|right|Cleve in the lab, c. 1900]]
Cleve worked on the synthesis of complex chemical compounds until 1872.<ref name = "encyclopedia"/> He theorized in 1874 that the element [[didymium]] consisted of two elements. This theory was proven right with the discovery of [[praseodymium]] and [[neodymium]] in 1885 by [[Carl Auer von Welsbach]]. In 1879, Cleve proved that the newly discovered element [[scandium]] was an element predicted by [[Dmitri Mendeleev]] to be "eka-boron".<ref name = "britannica"/> He isolated a quantity of scandium in this same year and determined its [[atomic weight]].<ref name = "encyclopedia"/> He discovered the element [[holmium]] in 1879 by examining a sample of [[erbium oxide]].<ref name="Virginia"/><ref name = "chemicool">{{Citation|author = Doug Stewart|work=chemicool.com|url = http://www.chemicool.com/elements/holmium.html|title = Holmium Element Facts / Chemistry|access-date = 14 March 2014}}</ref> While removing impurities from a sample of erbium oxide, Cleve discovered a brown substance and a green substance, and the brown substance was [[holmium oxide]] (the green substance was [[thulium oxide]]).<ref name = "chemicool"/><ref>{{Citation|url = http://pss.scdsb.on.ca/Departments/Science/SCH4U/Brad/Holmium%20Website/thetrueindex.html|author = Bradley Brooks|work = Penetanguishene Secondary School|title = Introduction to Holmium|access-date = 14 March 2014|url-status = dead|archiveurl = https://web.archive.org/web/20140315045124/http://pss.scdsb.on.ca/Departments/Science/SCH4U/Brad/Holmium%20Website/thetrueindex.html|archivedate = 15 March 2014|df = dmy-all}}</ref> However, this sample may have been impure.<ref>{{Citation|author = John Emsley|author-link = John Emsley|url = https://books.google.com/books?id=4BAg769RfKoC&pg=PA220|title = Nature's Building Blocks An A-Z Guide to the Elements New Edition|pages = 224, 225|year = 2011|publisher=Oxford University Press|isbn=978-0199605637}}</ref> He separated [[thulium]] from an erbium oxide sample in 1879.<ref>{{Citation|author = John Emsley|author-link = John Emsley|url = https://books.google.com/books?id=4BAg769RfKoC&pg=PA220|title = Nature's Building Blocks An A-Z Guide to the Elements New Edition|page = 549|year = 2011|publisher=Oxford University Press|isbn=978-0199605637}}</ref> Additionally, Cleve and [[Abraham Langlet]] discovered [[helium]] in the mineral cleveite in 1895.<ref name="Marshall">{{cite journal |last1=Marshall |first1=James L. |last2=Marshall |first2=Virginia R. |title=Rediscovery of the Elements: Helium |journal=The Hexagon |date=2012 |issue=Spring |pages=20–29 |url=http://www.chem.unt.edu/~jimm/REDISCOVERY%207-09-2018/Hexagon%20Articles/helium.pdf |access-date=30 December 2019}}</ref><ref name="Virginia">{{cite journal |last1=Marshall |first1=James L. Marshall |last2=Marshall |first2=Virginia R. Marshall |title=Rediscovery of the elements: The Rare Earths–The Confusing Years |journal=The Hexagon |date=2015 |pages=72–77 |url=http://www.chem.unt.edu/~jimm/REDISCOVERY%207-09-2018/Hexagon%20Articles/rare%20earths%20II.pdf |access-date=30 December 2019}}</ref><ref name="Weeks">{{cite book |last1=Weeks |first1=Mary Elvira |title=The discovery of the elements |date=1956 |publisher=Journal of Chemical Education |location=Easton, PA |url=https://archive.org/details/discoveryoftheel002045mbp |edition=6th }}</ref><ref>{{Citation|author = Giora Shaviv|url = https://books.google.com/books?id=tb5WFYlNbeAC&pg=PA52|publisher=Springer|title = Life of Stars: The Controversial Inception and Emergence of the Theory of Stellar Structure|date = 2009|isbn = 9783642020889}}</ref>

Cleve discovered six forms of [[dichloronaphthalene]] and discovered  [[aminonaphthalenesulfonic acids]], which are sometimes named after him.<ref name = "britannica"/> He prepared a number of nitrosulfonic acids as well.<ref name = "collected"/> In 1883, Cleve was the first person to describe the plankton species ''[[Nitzschia seriata]]''.<ref name = "nndb">{{Citation|url = http://www.nndb.com/people/143/000213501/|title = Per Theodor Cleve|access-date = 13 March 2014}}</ref> In 1890, Cleve began to mainly focus on the  field of [[biology]], mainly studying freshwater [[algae]], [[diatom]]s, and [[plankton]].<ref name = "britannica"/> Cleve participated in a Swedish expedition to [[Spitsbergen]] in 1898. While on this mission, he discovered a number of species of [[spumellarian]]s, [[nassellarian]]s, and [[phaeodarian]]s.<ref>{{Citation|author1=Kjell R. Bjørklund |author2=Takuya Itaki |author3=Jane K. Dolven |doi=10.1144/jmpaleo2012-024 |title = Per Theodor Cleve: a short résumé and his radiolarian results from the Swedish Expedition to Spitsbergen in 1898|journal=Journal of Micropalaeontology|volume=33|pages= 59–93|year=2014 |doi-access=free }}</ref> With [[Johann Diedrich Möller]] he issued and distributed an [[exsiccata]]-like series of microscope slides under the title ''Diatoms edited by P. T. Cleve and J. D. Möller''.<ref>{{cite web |title=Diatoms edited by P. T. Cleve and J. D. Möller: IndExs ExsiccataID=1861060991 |website=IndExs – Index of Exsiccatae |publisher=Botanische Staatssammlung München |url=https://www.botanischestaatssammlung.de/DatabaseClients/IndExs/Exsiccatae_IndExs_Details.jsp?ExsiccataID=1861060991 |access-date=18 July 2024}}</ref>

Cleve, in collaboration with 
[[Otto Höglund]]<!-- Otto Magnus Höglund --> 
prepared numerous previously-undiscovered [[salt (chemistry)|salts]] of [[yttrium]] and erbium. The two also did work on the chemistry of the chemical elements [[thorium]] and [[lanthanum]]. By 1874, Cleve discovered that thorium was a [[wikt:quadrivalent|quadrivalent]] element and also determined lanthanum to be [[wikt:trivalent|trivalent]]. These findings were initially doubted by the scientific community.<ref name = "collected"/>

Cleve was the first observer of [[isomer]]ism in [[platinumamine]] derivatives.<ref name = "acs"/>

Additionally, Cleve created a method of dating glacial and post-glacial deposits in the [[fossil record]].<ref name = "nndb"/>

Cleve's PhD [[dissertation]] was "Mineral-analytiska under-sökningar". He wrote a paper on [[samarium]] in 1879 and ''The Seasonal Distribution of Atlantic Plankton Organisms'' in 1900.<ref name = "britannica"/><ref name = "encyclopedia"/> In 1883, he published ''Kemiskt Handlexicon'', which translates to ''Chemical Handbook''. Notable students of Cleve include [[Ellen Fries]] (the first Swedish woman to earn a [[PhD]]) and [[Svante Arrhenius]] (a winner of the [[Nobel Prize]]).<ref name = "nndb"/>

Cleve also studied [[hydrography]] and [[geology]].<ref name = "nndb"/>

==Personal life, family, and death==
In 1874, Cleve married [[: se : Alma Cleve|Carolina Alma "Caralma" Öhbom]] (known as Alma Cleve), a teacher and author;<ref name = "nndb"/> the couple had three daughters. The first daughter, [[Astrid Cleve|Astrid Maria Cleve]] (born 22 January 1875), became a [[botanist]].<ref name = "nndb"/><ref>{{Citation|url = https://books.google.com/books?id=RhNl22fb5xIC&pg=PA2|title = Ladies in the Laboratory 2|date = 2004|author1=Mary R. S. Creese |author2=Thomas M. Creese |publisher=Scarecrow Press|isbn=0810849798}}</ref> His son-in-law and grandson, [[Hans von Euler-Chelpin]] and [[Ulf von Euler]], both won Nobel Prizes.<ref name = "nndb"/> Cleve was friends with [[Thomas Edward Thorpe]].<ref name = "collected">{{Citation|author = Chemical Society (Great Britain), Sir Humphry Davy, Bureau of Chemical Abstracts (Great Britain)|url = https://books.google.com/books?id=XSRLAAAAYAAJ&pg=PA1301|title = The collected works of Sir Humphry Davy ...: Discourses delivered before the Royal society. Elements of agricultural chemistry, pt. I|date = 21 June 1906|publisher=Smith, Elder and Company}}</ref> The second daughter, [[: se : Agnes Cleve-Jonand|Agnes Cleve-Jonand]] (born Agnes Elisabet Cleve) (1876-1951), was a visual artist and pioneer of Modernism in Sweden. The third and last daughter, [[: se : Célie Brunius|Célie Brunius]] (born Gerda Cecilia Afrodite Cleve) (1882-1980), was a journalist. His daughter Agnes was married to illustrator, set designer and artist [[: se : John Jon-And|John Jon-And]]. His daughter Célie was married to writer [[: se : August Brunius|August Brunius]] and was the mother of artist [[: se : Göran Brunius|Göran Brunius]], journalist [[: se : Clas Brunius|Clas Brunius]] and associate professor [[: se : Teddy Brunius|Teddy Brunius]]. The television host and politician [[Lisette Schulman]] was his great-granddaughter.

Per Teodore Cleve was a supporter of [[women's equality]] and [[Ellen Fries]], the first Swedish woman to receive a PhD, was one of his students.<ref name = "nndb"/>

Cleve began experiencing [[pleurisy]] in December 1904 and it affected his heart. He thought that he had recovered by the spring of 1905, and he returned home to Uppsala, Sweden,.<ref name = "collected"/> but he died there on 18 June 1905.<ref name = "britannica"/>

==Awards and legacy==
Cleve joined the [[Royal Swedish Academy of Sciences]] in 1871. He received a [[Davy Medal]] in 1894 and 1904.<ref name = "nndb"/><ref name = "acs"/>

The mineral [[cleveite]] is named for Cleve.<ref name = "nndb"/>

==References==
{{Reflist|35em}}

==External links==
{{Commons category}}
* {{Gutenberg author |id=5385| name=Per Teodor Cleve}}
* {{Internet Archive author |sname=Per Teodor Cleve}}

{{Authority control}}

{{DEFAULTSORT:Cleve, Per Teodor}}
[[Category:1840 births]]
[[Category:1905 deaths]]
[[Category:19th-century Swedish chemists]]
[[Category:Burials at Uppsala old cemetery]]
[[Category:Discoverers of chemical elements]]
[[Category:Holmium]]
[[Category:Members of the Royal Swedish Academy of Sciences]]
[[Category:Scientists from Stockholm]]
[[Category:Neodymium]]
[[Category:Praseodymium]]
[[Category:19th-century Swedish geologists]]
[[Category:Swedish people of German descent]]
[[Category:Thulium]]
[[Category:Uppsala University alumni]]
[[Category:Rare earth scientists]]