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Per Teodor Cleve (10 February 1840 – 18 June 1905) was a Swedish
chemist A chemist (from Greek ''chēm(ía)'' alchemy; replacing ''chymist'' from Medieval Latin ''alchemist'') is a scientist trained in the study of chemistry. Chemists study the composition of matter and its properties. Chemists carefully describe th ...
,
biologist A biologist is a scientist who conducts research in biology. Biologists are interested in studying life on Earth, whether it is an individual cell, a multicellular organism, or a community of interacting populations. They usually specialize in ...
,
mineralogist Mineralogy is a subject of geology specializing in the scientific study of the chemistry, crystal structure, and physical (including optical) properties of minerals and mineralized artifacts. Specific studies within mineralogy include the proc ...
and
oceanographer Oceanography (), also known as oceanology and ocean science, is the scientific study of the oceans. It is an Earth science, which covers a wide range of topics, including ecosystem dynamics; ocean currents, waves, and geophysical fluid dynamic ...
. He is best known for his discovery of the chemical elements
holmium Holmium is a chemical element with the symbol Ho and atomic number 67. It is a rare-earth element and the eleventh member of the lanthanide series. It is a relatively soft, silvery, fairly corrosion-resistant and malleable metal. Like a lot of oth ...
and
thulium Thulium is a chemical element with the symbol Tm and atomic number 69. It is the thirteenth and third-last element in the lanthanide series. Like the other lanthanides, the most common oxidation state is +3, seen in its oxide, halides and other c ...
. Born in Stockholm in 1840, Cleve earned his
BSc A Bachelor of Science (BS, BSc, SB, or ScB; from the Latin ') is a bachelor's degree awarded for programs that generally last three to five years. The first university to admit a student to the degree of Bachelor of Science was the University ...
and PhD from
Uppsala University Uppsala University ( sv, Uppsala universitet) is a public research university in Uppsala, Sweden. Founded in 1477, it is the oldest university in Sweden and the Nordic countries still in operation. The university rose to significance during ...
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 Didymium ( el, , twin) is a mixture of the elements praseodymium and neodymium. It is used in safety glasses for glassblowing and blacksmithing, especially with a gas (propane)-powered forge, where it provides a filter that selectively blocks ...
was in fact two elements; this theory was confirmed in 1885 when
Carl Auer von Welsbach Carl Auer von Welsbach (1 September 1858 – 4 August 1929), who received the Austrian noble title of Freiherr Auer von Welsbach in 1901, was an Austrian scientist and inventor, who separated didymium into the elements neodymium and praseody ...
discovered
neodymium Neodymium is a chemical element with the symbol Nd and atomic number 60. It is the fourth member of the lanthanide series and is considered to be one of the rare-earth metals. It is a hard, slightly malleable, silvery metal that quickly tarnishes i ...
and
praseodymium Praseodymium is a chemical element with the symbol Pr and the atomic number 59. It is the third member of the lanthanide series and is considered to be one of the rare-earth metals. It is a soft, silvery, malleable and ductile metal, valued for i ...
. In 1879 Cleve discovered holmium and thulium. 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
deposits A deposit account is a bank account maintained by a financial institution in which a customer can deposit and withdraw money. Deposit accounts can be savings accounts, current accounts or any of several other types of accounts explained below. ...
from the types of
diatom A diatom ( Neo-Latin ''diatoma''), "a cutting through, a severance", from el, διάτομος, diátomos, "cut in half, divided equally" from el, διατέμνω, diatémno, "to cut in twain". is any member of a large group comprising se ...
fossils in the deposits, and wrote a seminal text in the field of oceanography. He died in 1905 at age 65.


Early life

Cleve was born in
Stockholm Stockholm () is the capital and largest city of Sweden as well as the largest urban area in Scandinavia. Approximately 980,000 people live in the municipality, with 1.6 million in the urban area, and 2.4 million in the metropolita ...
, Sweden, as the thirteenth child of his father, a merchant known as Fredrik Theodor Cleve. Cleve's ancestors on his father's side came from western Germany and settled in Sweden in the late 18th century. Cleve showed interest in natural science and natural history from an early age. He attended the Stockholms Lyceum in 1858, studying chemistry and biology. He gained a Bachelor of Science degree from the University of Uppsala in 1863 and a PhD from the same university in 1868.


Career

In 1860, aged 20, Cleve became
assistant professor Assistant Professor is an academic rank just below the rank of an associate professor used in universities or colleges, mainly in the United States and Canada. Overview This position is generally taken after earning a doctoral degree and general ...
of
mineralogy Mineralogy is a subject of geology specializing in the scientific study of the chemistry, crystal structure, and physical (including optical) properties of minerals and mineralized artifacts. Specific studies within mineralogy include the proc ...
at the
University of Uppsala Uppsala University ( sv, Uppsala universitet) is a public research university in Uppsala, Sweden. Founded in 1477, it is the oldest university in Sweden and the Nordic countries still in operation. The university rose to significance during ...
, and was appointed assistant professor of chemistry in 1868. He also taught at the
Royal Institute of Technology The KTH Royal Institute of Technology ( sv, Kungliga Tekniska högskolan, lit=Royal Institute of Technology), abbreviated KTH, is a public research university in Stockholm, Sweden. KTH conducts research and education in engineering and technolo ...
between 1870 and 1874, and eventually became professor of
general A general officer is an officer of high rank in the armies, and in some nations' air forces, space forces, and marines or naval infantry. In some usages the term "general officer" refers to a rank above colonel."general, adj. and n.". OED On ...
and
agricultural chemistry Agricultural chemistry is the study of chemistry, especially organic chemistry and biochemistry, as they relate to agriculture—agricultural production, the processing of raw products into foods and beverages, and environmental monitoring and r ...
at the University of Uppsala. 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 The Nobel Committee for Chemistry is the Nobel Committee responsible for proposing laureates for the Nobel Prize in Chemistry. Cleve's first work was ''Några ammoniakaliska chromföreningar'' (''Some compounds of ammonia and chromium'', 1861). He also wrote several more papers on complex compounds, including the compounds of platinum. Additionally, Cleve synthesized several hundred complex platinum compounds. Cleve visited a number of laboratories in England, France, Italy, and Switzerland in the 1860s. While in Paris, he visited the laboratory of
Charles-Adolphe Wurtz Charles Adolphe Wurtz (; 26 November 181710 May 1884) was an Alsatian French chemist. He is best remembered for his decades-long advocacy for the atomic theory and for ideas about the structures of chemical compounds, against the skeptical opinio ...
and also made a number of friends there. Cleve worked on the synthesis of complex chemical compounds until 1872. He theorized in 1874 that the element
didymium Didymium ( el, , twin) is a mixture of the elements praseodymium and neodymium. It is used in safety glasses for glassblowing and blacksmithing, especially with a gas (propane)-powered forge, where it provides a filter that selectively blocks ...
consisted of two elements. This theory was proven right with the discovery of
praseodymium Praseodymium is a chemical element with the symbol Pr and the atomic number 59. It is the third member of the lanthanide series and is considered to be one of the rare-earth metals. It is a soft, silvery, malleable and ductile metal, valued for i ...
and
neodymium Neodymium is a chemical element with the symbol Nd and atomic number 60. It is the fourth member of the lanthanide series and is considered to be one of the rare-earth metals. It is a hard, slightly malleable, silvery metal that quickly tarnishes i ...
in 1885 by
Carl Auer von Welsbach Carl Auer von Welsbach (1 September 1858 – 4 August 1929), who received the Austrian noble title of Freiherr Auer von Welsbach in 1901, was an Austrian scientist and inventor, who separated didymium into the elements neodymium and praseody ...
. In 1879, Cleve proved that the newly discovered element
scandium Scandium is a chemical element with the symbol Sc and atomic number 21. It is a silvery-white metallic d-block element. Historically, it has been classified as a rare-earth element, together with yttrium and the Lanthanides. It was discovered in ...
was an element predicted by
Dmitri Mendeleev Dmitri Ivanovich Mendeleev (sometimes transliterated as Mendeleyev or Mendeleef) ( ; russian: links=no, Дмитрий Иванович Менделеев, tr. , ; 8 February Old_Style_and_New_Style_dates">O.S._27_January.html" ;"title="O ...
to be "eka-boron". He isolated a quantity of scandium in this same year and determined its
atomic weight Relative atomic mass (symbol: ''A''; sometimes abbreviated RAM or r.a.m.), also known by the deprecated synonym atomic weight, is a dimensionless physical quantity defined as the ratio of the average mass of atoms of a chemical element in a giv ...
. He discovered the element
holmium Holmium is a chemical element with the symbol Ho and atomic number 67. It is a rare-earth element and the eleventh member of the lanthanide series. It is a relatively soft, silvery, fairly corrosion-resistant and malleable metal. Like a lot of oth ...
in 1879 by examining a sample of
erbium oxide Erbium(III) oxide is the inorganic compound with the formula . It is a pink paramagnetic solid. It finds uses in various optical materials. Structure Erbium(III) oxide has a cubic structure resembling the bixbyite motif. The Er3+ centers are oc ...
. 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 Thulium(III) oxide is a pale green solid compound, with the formula Tm2 O3. It was first isolated in 1879, from an impure sample of erbia, by Swedish chemist Per Teodor Cleve, who named it ''thulia''. It can be prepared in the laboratory by burn ...
). However, this sample may have been impure. He separated
thulium Thulium is a chemical element with the symbol Tm and atomic number 69. It is the thirteenth and third-last element in the lanthanide series. Like the other lanthanides, the most common oxidation state is +3, seen in its oxide, halides and other c ...
from an erbium oxide sample in 1879. Additionally, Cleve and Abraham Langlet discovered
helium Helium (from el, ἥλιος, helios, lit=sun) is a chemical element with the symbol He and atomic number 2. It is a colorless, odorless, tasteless, non-toxic, inert, monatomic gas and the first in the noble gas group in the periodic table. It ...
in the mineral cleveite in 1895. Cleve discovered six forms of dichloronaphthalene and discovered aminonaphthalenesulfonic acids, which are sometimes named after him. He prepared a number of nitrosulfonic acids as well. In 1883, Cleve was the first person to describe the plankton species '' Nitzschia seriata''. In 1890, Cleve began to mainly focus on the field of
biology Biology is the scientific study of life. It is a natural science with a broad scope but has several unifying themes that tie it together as a single, coherent field. For instance, all organisms are made up of cells that process hereditary ...
, mainly studying freshwater
algae Algae (; singular alga ) is an informal term for a large and diverse group of photosynthesis, photosynthetic eukaryotic organisms. It is a polyphyletic grouping that includes species from multiple distinct clades. Included organisms range from u ...
,
diatom A diatom ( Neo-Latin ''diatoma''), "a cutting through, a severance", from el, διάτομος, diátomos, "cut in half, divided equally" from el, διατέμνω, diatémno, "to cut in twain". is any member of a large group comprising se ...
s, and
plankton Plankton are the diverse collection of organisms found in water (or air) that are unable to propel themselves against a current (or wind). The individual organisms constituting plankton are called plankters. In the ocean, they provide a crucia ...
. Cleve participated in a Swedish expedition to
Spitsbergen Spitsbergen (; formerly known as West Spitsbergen; Norwegian: ''Vest Spitsbergen'' or ''Vestspitsbergen'' , also sometimes spelled Spitzbergen) is the largest and the only permanently populated island of the Svalbard archipelago in northern No ...
in 1898. While on this mission, he discovered a number of species of spumellarians, nassellarians, and phaeodarians. Cleve, in collaboration with Otto Höglund prepared numerous previously-undiscovered
salts In chemistry, a salt is a chemical compound consisting of an ionic assembly of positively charged cations and negatively charged anions, which results in a compound with no net electric charge. A common example is table salt, with positively cha ...
of
yttrium Yttrium is a chemical element with the symbol Y and atomic number 39. It is a silvery-metallic transition metal chemically similar to the lanthanides and has often been classified as a "rare-earth element". Yttrium is almost always found in co ...
and erbium. The two also did work on the chemistry of the chemical elements thorium and
lanthanum Lanthanum is a chemical element with the symbol La and atomic number 57. It is a soft, ductile, silvery-white metal that tarnishes slowly when exposed to air. It is the eponym of the lanthanide series, a group of 15 similar elements between lant ...
. By 1874, Cleve discovered that thorium was a quadrivalent element and also determined lanthanum to be
trivalent In chemistry, the valence (US spelling) or valency (British spelling) of an element is the measure of its combining capacity with other atoms when it forms chemical compounds or molecules. Description The combining capacity, or affinity of an ...
. These findings were initially doubted by the scientific community. Cleve was the first observer of
isomer In chemistry, isomers are molecules or polyatomic ions with identical molecular formulae – that is, same number of atoms of each element – but distinct arrangements of atoms in space. Isomerism is existence or possibility of isomers. I ...
ism in platinumamine derivatives. Additionally, Cleve created a method of dating glacial and post-glacial deposits in the
fossil record A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved in ...
. Cleve's PhD dissertation was "Mineral-analytiska under-sökningar". He wrote a paper on
samarium Samarium is a chemical element with symbol Sm and atomic number 62. It is a moderately hard silvery metal that slowly oxidizes in air. Being a typical member of the lanthanide series, samarium usually has the oxidation state +3. Compounds of samar ...
in 1879 and ''The Seasonal Distribution of Atlantic Plankton Organisms'' in 1900. In 1883, he published ''Kemiskt Handlexicon'', which translates to ''Chemical Handbook''. Notable students of Cleve include
Ellen Fries Ellen Fries (23 September 1855 – 31 March 1900) was a Swedish feminist and writer. She became the first female Ph.D. in Sweden in 1883. She was also involved in founding several women's organizations. Biography She born in 1855 at Rödslegå ...
(the first Swedish woman to earn a PhD) and
Svante Arrhenius Svante August Arrhenius ( , ; 19 February 1859 – 2 October 1927) was a Swedish scientist. Originally a physicist, but often referred to as a chemist, Arrhenius was one of the founders of the science of physical chemistry. He received the Nob ...
(a winner of the
Nobel Prize The Nobel Prizes ( ; sv, Nobelpriset ; no, Nobelprisen ) are five separate prizes that, according to Alfred Nobel's will of 1895, are awarded to "those who, during the preceding year, have conferred the greatest benefit to humankind." Alfr ...
). Cleve also studied
hydrography Hydrography is the branch of applied sciences which deals with the measurement and description of the physical features of oceans, seas, coastal areas, lakes and rivers, as well as with the prediction of their change over time, for the primary p ...
and
geology Geology () is a branch of natural science concerned with Earth and other astronomical objects, the features or rocks of which it is composed, and the processes by which they change over time. Modern geology significantly overlaps all other Ear ...
.


Personal life, family, and death

In 1874, Cleve married Carolina Alma "Caralma" Öhbom (known as Alma Cleve), a teacher and author; the couple had three daughters. The first daughter, Astrid Maria Cleve (born 22 January 1875), became a
botanist Botany, also called , plant biology or phytology, is the science of plant life and a branch of biology. A botanist, plant scientist or phytologist is a scientist who specialises in this field. The term "botany" comes from the Ancient Greek w ...
. His son-in-law and grandson, Hans von Euler-Chelpin and
Ulf von Euler Ulf Svante von Euler (7 February 1905 – 9 March 1983) was a Swedish physiologist and pharmacologist. He shared the Nobel Prize in Physiology or Medicine in 1970 for his work on neurotransmitters. Life Ulf Svante von Euler-Chelpin was born in S ...
, both won Nobel Prizes. Cleve was friends with Thomas Edward Thorpe. The second daughter, Agnes Cleve-Jonand (born Agnes Elisabet Cleve) (1876-1951), was a visual artist and pioneer of Modernism in Sweden. The third and last daughter, Célie Brunius (born Gerda Cecilia Afrodite Cleve) (1882-1980), was a journalist. His daughter Agnes was married to illustrator, set designer and artist John Jon-And. His daughter Célie was married to writer August Brunius and was the mother of artist Göran Brunius, journalist Clas Brunius and associate professor 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 Ellen Fries (23 September 1855 – 31 March 1900) was a Swedish feminist and writer. She became the first female Ph.D. in Sweden in 1883. She was also involved in founding several women's organizations. Biography She born in 1855 at Rödslegå ...
, the first Swedish woman to receive a PhD, was one of his students. Cleve began experiencing
pleurisy Pleurisy, also known as pleuritis, is inflammation of the membranes that surround the lungs and line the chest cavity (pleurae). This can result in a sharp chest pain while breathing. Occasionally the pain may be a constant dull ache. Other sy ...
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,. but he died there on 18 June 1905.


Awards and legacy

Cleve joined the
Royal Swedish Academy of Sciences The Royal Swedish Academy of Sciences ( sv, Kungliga Vetenskapsakademien) is one of the royal academies of Sweden. Founded on 2 June 1739, it is an independent, non-governmental scientific organization that takes special responsibility for prom ...
in 1871. He received a
Davy Medal The Davy Medal is awarded by the Royal Society of London "for an outstandingly important recent discovery in any branch of chemistry". Named after Humphry Davy, the medal is awarded with a monetary gift, initially of £1000 (currently £2000). H ...
in 1894 and 1904. The mineral cleveite is named for Cleve.


References


External links

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