Presentation Speech by former Councillor T. Nordström, President of the Royal Swedish Academy of Sciences, on December 10, 1913
Your Majesty, Your
Royal Highnesses, Ladies and Gentlemen.
The
Royal Academy of Sciences has awarded this year's Nobel Prize for Chemistry to
Alfred Werner, Professor in the University of Zürich, "for 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".
The concept of valence on which all modern chemical theory is based had
been found unable to deal with a large and important group of mainly inorganic
compounds, the so-called complex or molecular compounds, because it was unable
to provide a satisfactory explanation of their internal structure. By considerably
expanding and modifying the former concept of valence, Werner both illuminated
the area concerned and opened up new paths for research.
By contrast
with the conventional view, Werner does not conceive of the binding forces of
an atom as being divided into certain units of affinity determined in number and
direction. He considers affinity rather to be a force issuing from the centre
of the atom, uniformly attractive in all directions, whose geometrical expression
is therefore not a given number of guiding lines, but a spherical surface. Atoms
or atom groups which can occur as ions or whose chemical binding capacity is equivalent
thereto, can enter bonds in the manner previously indicated by means of the so-called
primary valences. These do not however represent the sum total of affinities;
the remaining residual affinities or secondary valences, whose energy content
is assumed to be less than that of the primary valences, but which do not otherwise
in principle differ from them, bring about bonds with atomic complexes which cannot
occur as independent ions, e.g. water, ammonia, potassium chloride, etc. and thus
make provision for compounds of higher order, so-called addition and intercalation
compounds.
The number of atoms or groups of atoms which can be linked
in a first sphere with the elementary atom functioning as centre, or which in
other words can be coordinated into complex radicals under direct linkage with
an atom, Werner calls the coordination number. This is a dearly defined
numerical concept which is superior to other numerical concepts designed to characterize
affinity saturation in that it is to some extent independent of the nature and
valence of the interconnected elementary atoms, in so far as it has the same value
for the great majority of elements. Only two such numerical values have been demonstrated
as yet, i.e. four for some elements, and six for the others.
By this
approach of which only some principal characteristics can be mentioned here, Werner
explains the structure and origin of complex inorganic compounds. By widening
and deepening the concept of valence which incorporates his view he has succeeded
in bringing atomistic and molecular compounds together under a common point of
view. He has drawn a large number of diverse compounds into the range of his comprehensive
expert mental work and has thereby been able to establish a uniform system for
large groups of inorganic compounds. Werner's approach has also exerted significant
influence on research in organic chemistry.
Werner's theory has been
supported in an extremely important and valuable manner by the stereochemical
researches which he carried out as a sideline, mostly in connection with his work
on the constitution of chemical compounds.
By virtue of his theory
of the asymmetrical carbon atom, van't Hoff became the real founder of the stereochemistry
of organic compounds, and it is Werner's indisputable merit to have introduced
this approach to inorganic chemistry as well. Even in his earlier investigations
into certain metal ammonias he was able to show that numerous cases of isomerism
in complex cobalt and platinum compounds could only be satisfactorily explained
by steric approach. For complex radicals of a certain type he put forward a steric
theory - the octahedron theory - which predicted that certain of these compounds
must occur in two stereoisomeric forms, a prediction which has been confirmed
by experiment. By far the greatest interest in this field attaches also to the
discovery he made in the last few years, that certain cobalt, chromium, iron,
and radium compounds with an asymmetrical metal atom in the complex radical can
be divided into two forms which behave like mirror images and show differences
of the same kind as those in organic mirror-image isomers, i.e. they are optical
antipodes of each other. This discovery is a splendid support for Werner's theory.
It has been called the most important discovery in chemistry in recent times,
and his stereochemical work makes him the founder of inorganic stereochemistry.
As to Werner's research work as a whole we can with good reason agree with
the remark of an eminent research worker, that Werner's theoretical and experimental
work in inorganic chemistry has opened up new paths of chemical research and is
of positively revolutionary significance. It is substantially his researches which
have during the last few decades set the trend of development in inorganic chemistry
and have newly inspired this branch of science which had been somewhat neglected
during the last quarter of the 19th century, by giving it new impulses which have
borne fruit in numerous different special studies by various research workers.
From Nobel Lectures, Chemistry 1901-1921, Elsevier Publishing Company, Amsterdam, 1966
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