Alfred Werner (12 December 1866 – 15 November 1919) was a Swiss
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 ...
who was a student at
ETH Zurich
(colloquially)
, former_name = eidgenössische polytechnische Schule
, image = ETHZ.JPG
, image_size =
, established =
, type = Public
, budget = CHF 1.896 billion (2021)
, rector = Günther Dissertori
, president = Joël Mesot
, ac ...
and a professor at the
University of Zurich
The University of Zürich (UZH, german: Universität Zürich) is a public research university located in the city of Zürich, Switzerland. It is the largest university in Switzerland, with its 28,000 enrolled students. It was founded in 1833 f ...
. He won the
Nobel Prize in Chemistry
)
, image = Nobel Prize.png
, alt = A golden medallion with an embossed image of a bearded man facing left in profile. To the left of the man is the text "ALFR•" then "NOBEL", and on the right, the text (smaller) "NAT•" then "M ...
in 1913 for proposing the
octahedral
In geometry, an octahedron (plural: octahedra, octahedrons) is a polyhedron with eight faces. The term is most commonly used to refer to the regular octahedron, a Platonic solid composed of eight equilateral triangles, four of which meet a ...
configuration of
transition metal
In chemistry, a transition metal (or transition element) is a chemical element in the d-block of the periodic table (groups 3 to 12), though the elements of group 12 (and less often group 3) are sometimes excluded. They are the elements that can ...
complexes. Werner developed the basis for modern
coordination chemistry
A coordination complex consists of a central atom or ion, which is usually metallic and is called the ''coordination centre'', and a surrounding array of bound molecules or ions, that are in turn known as ''ligands'' or complexing agents. Many ...
. He was the first
inorganic chemist
Inorganic chemistry deals with synthesis and behavior of inorganic and organometallic compounds. This field covers chemical compounds that are not carbon-based, which are the subjects of organic chemistry. The distinction between the two disci ...
to win the Nobel prize, and the only one prior to 1973.
[https://www.nobelprize.org/nobel_prizes/chemistry/laureates/1913/werner-bio.html Nobel Prize Retrieved 1 December 2012]
Biography
Werner was born in 1866 in
Mulhouse
Mulhouse (; Alsatian language, Alsatian: or , ; ; meaning ''Mill (grinding), mill house'') is a city of the Haut-Rhin Departments of France, department, in the Grand Est Regions of France, region, eastern France, close to the France–Switzerl ...
,
Alsace
Alsace (, ; ; Low Alemannic German/ gsw-FR, Elsàss ; german: Elsass ; la, Alsatia) is a cultural region and a territorial collectivity in eastern France, on the west bank of the upper Rhine next to Germany and Switzerland. In 2020, it had ...
(which was then part of France, but which was annexed by Germany in 1871). He was raised as
Roman Catholic
Roman or Romans most often refers to:
*Rome, the capital city of Italy
*Ancient Rome, Roman civilization from 8th century BC to 5th century AD
*Roman people, the people of ancient Rome
*'' Epistle to the Romans'', shortened to ''Romans'', a lette ...
.
He was the fourth and last child of Jean-Adam Werner, a foundry worker, and his second wife, Salomé Jeanette Werner, who originated from a wealthy family.
He went to Switzerland to study chemistry at the
Swiss Federal Institute (Polytechnikum) in Zurich, but since this institute was not empowered to grant doctorates until 1909, Werner received a doctorate formally from the University of Zürich in 1890.
After postdoctoral study in
Paris
Paris () is the capital and most populous city of France, with an estimated population of 2,165,423 residents in 2019 in an area of more than 105 km² (41 sq mi), making it the 30th most densely populated city in the world in 2020. S ...
, he returned to the Swiss Federal Institute to teach (1892). In 1893 he moved to the
University of Zurich
The University of Zürich (UZH, german: Universität Zürich) is a public research university located in the city of Zürich, Switzerland. It is the largest university in Switzerland, with its 28,000 enrolled students. It was founded in 1833 f ...
, where he became a professor in 1895. In 1894 he became a Swiss citizen.
In his last year, he was suffering from a general, progressive, degenerative
arteriosclerosis
Arteriosclerosis is the thickening, hardening, and loss of elasticity of the walls of Artery, arteries. This process gradually restricts the blood flow to one's organs and tissues and can lead to severe health risks brought on by atherosclerosis ...
, especially of the brain, aggravated by years of excessive drinking and overwork. He died in a psychiatric hospital in Zurich.
Werner died on 15 November 1919 of
arteriosclerosis
Arteriosclerosis is the thickening, hardening, and loss of elasticity of the walls of Artery, arteries. This process gradually restricts the blood flow to one's organs and tissues and can lead to severe health risks brought on by atherosclerosis ...
in
Zürich
Zürich () is the list of cities in Switzerland, largest city in Switzerland and the capital of the canton of Zürich. It is located in north-central Switzerland, at the northwestern tip of Lake Zürich. As of January 2020, the municipality has 43 ...
at the age of 52.
Research
Coordination chemistry
In 1893, Werner was the first to propose correct structures for coordination compounds containing
complex ions, in which a central transition metal atom is surrounded by neutral or anionic
ligands
In coordination chemistry, a ligand is an ion or molecule (functional group) that binds to a central metal atom to form a coordination complex. The bonding with the metal generally involves formal donation of one or more of the ligand's electro ...
.
For example, it was known that cobalt forms a "complex" hexamminecobalt(III) chloride, with formula CoCl
3•6NH
3, but the nature of the association indicated by the dot was mysterious. Werner proposed the structure
Co(NH3)6/nowiki>Cl3">/nowiki>Co(NH3)6/nowiki>Cl
3, with the Co
3+ ion surrounded by six NH
3 at the vertices of an octahedron. The three Cl
− are dissociated as free ions, which Werner confirmed by measuring the
conductivity
Conductivity may refer to:
*Electrical conductivity, a measure of a material's ability to conduct an electric current
**Conductivity (electrolytic), the electrical conductivity of an electrolyte in solution
** Ionic conductivity (solid state), ele ...
of the compound in aqueous solution, and also by chloride anion analysis using precipitation with
silver nitrate
Silver nitrate is an inorganic compound with chemical formula . It is a versatile precursor to many other silver compounds, such as those used in photography. It is far less sensitive to light than the halides. It was once called ''lunar caustic' ...
. Later,
magnetic susceptibility
In electromagnetism, the magnetic susceptibility (Latin: , "receptive"; denoted ) is a measure of how much a material will become magnetized in an applied magnetic field. It is the ratio of magnetization (magnetic moment per unit volume) to the ap ...
analysis was also used to confirm Werner's proposal for the chemical nature of CoCl
3•6NH
3.
For complexes with more than one type of ligand, Werner succeeded in explaining the number of
isomers
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.
...
observed. For example, he explained the existence of two tetrammine isomers, "Co(NH
3)
4Cl
3", one green and one purple. Werner proposed that these are two
geometric isomers
Geometry (; ) is, with arithmetic, one of the oldest branches of mathematics. It is concerned with properties of space such as the distance, shape, size, and relative position of figures. A mathematician who works in the field of geometry is ca ...
of formula
3)4Cl2">o(NH3)4Cl2l, with one Cl
− ion dissociated as confirmed by conductivity measurements. The Co atom is surrounded by four NH
3 and two Cl ligands at the vertices of an octahedron. The green isomer is "trans" with the two Cl ligands at opposite vertices, and the purple is "cis" with the two Cl at adjacent vertices.
Werner also prepared complexes with
optical isomers, and in 1914 he reported the first synthetic
chiral
Chirality is a property of asymmetry important in several branches of science. The word ''chirality'' is derived from the Greek (''kheir''), "hand", a familiar chiral object.
An object or a system is ''chiral'' if it is distinguishable from ...
compound lacking carbon, known as
hexol
In chemistry, hexol is a cation with formula 6+ — a coordination complex consisting of four cobalt cations in oxidation state +3, twelve ammonia molecules , and six hydroxy anions , with a net charge of +6. The hydroxy groups act as bridges b ...
with formula
3)4(OH)2)3">o(Co(NH3)4(OH)2)3r
6.
Nature of valence
Before Werner, chemists defined the
valence of an element as the number of its bonds without distinguishing different types of bond. However, in complexes such as
3)6">o(NH3)6l
3 for example, Werner considered that the Co-Cl bonds correspond to a "primary" valence of 3 at long distance, while the Co-NH
3 bonds which correspond to a "secondary" or weaker valence of 6 at shorter distance. This secondary valence of 6 he referred to as the
coordination number
In chemistry, crystallography, and materials science, the coordination number, also called ligancy, of a central atom in a molecule or crystal is the number of atoms, molecules or ions bonded to it. The ion/molecule/atom surrounding the central i ...
which he defined as the number of molecules (here of NH
3) directly linked to the central metal atom. In other complexes he found coordination numbers of 4 or 8.
On these views, and other similar views, in 1904
Richard Abegg
Richard Wilhelm Heinrich Abegg (9 January 1869 – 3 April 1910) was a German chemist and pioneer of valence theory. He proposed that the difference of the maximum positive and negative valence of an element tends to be eight. This has come to be ...
formulated what is now known as
Abegg's rule In chemistry, Abegg’s rule states that the difference between the maximum positive and negative valence of an element is frequently eight. The rule used a historic meaning of valence which resembles the modern concept of oxidation state in whic ...
which states that the difference between the maximum positive and negative
valence of an
element is frequently eight. This rule was used later in 1916 when
Gilbert N. Lewis formulated the "
octet rule
The octet rule is a chemical rule of thumb that reflects the theory that main-group elements tend to bond in such a way that each atom has eight electrons in its valence shell, giving it the same electronic configuration as a noble gas. The rul ...
" in his
cubical atom
The cubical atom was an early atomic model in which electrons were positioned at the eight corners of a cube in a non-polar atom or molecule. This theory was developed in 1902 by Gilbert N. Lewis and published in 1916 in the article "The Atom and ...
theory.
In modern terminology Werner's primary valence corresponds to the
oxidation state
In chemistry, the oxidation state, or oxidation number, is the hypothetical charge of an atom if all of its bonds to different atoms were fully ionic. It describes the degree of oxidation (loss of electrons) of an atom in a chemical compound. C ...
, and his secondary valence is called
coordination number
In chemistry, crystallography, and materials science, the coordination number, also called ligancy, of a central atom in a molecule or crystal is the number of atoms, molecules or ions bonded to it. The ion/molecule/atom surrounding the central i ...
. The Co-Cl bonds (in the above example) are now classed as ionic, and each Co-N bond is a
coordinate covalent bond
In coordination chemistry, a coordinate covalent bond, also known as a dative bond, dipolar bond, or coordinate bond is a kind of two-center, two-electron covalent bond in which the two electrons derive from the same atom. The bonding of metal io ...
between the
Lewis acid
A Lewis acid (named for the American physical chemist Gilbert N. Lewis) is a chemical species that contains an empty orbital which is capable of accepting an electron pair from a Lewis base to form a Lewis adduct. A Lewis base, then, is any sp ...
Co
3+ and the
Lewis base NH
3.
Works
* ''Lehrbuch der Stereochemie '' . Fischer, Jena 190
Digital editionby the
University and State Library Düsseldorf
The University and State Library Düsseldorf (german: Universitäts- und Landesbibliothek Düsseldorf, abbreviated ULB Düsseldorf) is a central service institution of Heinrich Heine University. Along with Bonn and Münster, it is also one of th ...
References
*
*
External links
* including the Nobel Lecture, 11 December 1913 ''On the Constitution and Configuration of Higher-Order Compounds''
The Nobel Prize in Chemistry 1913- short article about his work on the linkage of atoms in molecules by which he has thrown new light on earlier investigations and opened up new fields of research especially in inorganic chemistry.
{{DEFAULTSORT:Werner, Alfred
1866 births
1919 deaths
Scientists from Mulhouse
Inorganic chemists
Nobel laureates in Chemistry
Swiss Nobel laureates
ETH Zurich alumni
University of Zurich faculty
Swiss chemists
People involved with the periodic table