quantum mechanics proposed by Werner Heisenberg (1901–1976), in 1925, its
second interpretation by Erwin Schrödinger (1887.–1961.) in 1926, and the first
quantum-chemical calculation of the molecule published by Walter Heinrich
Heitler (1904–1981) and Fritz Wolfgang London (1900–1954) [4]. I will argue
that the Lewis theory about the electronic structure of molecules, which has its
origin in chemical reasoning, is conceptually and metaphysically analogous to
physical quantum mechanics that has appeared within the rigorous physical laws of
motion.
As I have demonstrated in previous lectures, chemical scientific methodology is
based on classifications. Creation of the structural theory and periodic system of
elements are the illustrative examples of the effectiveness of this epistemology in
the investigation of the microcosm. Lewis uses the same methodology in building
his theory about the chemical bond starting with chemical classifications: (i) dividing molecules in polar and nonpolar, and (ii) using the Abegg’s octet rule. Pierre
Duhem has argued that the method of classifications is in the relation with a sort of
“natural classification”, and that science oriented to the classification method led
science to form the deeper insight in the nature, than the science that forms only the
theories as its final product [5, 6]. Thus, science has to be oriented to classification.
Perhaps, the development of chemistry is an additional argument for the thesis of
Duhem.
For the beginning, I wish to focus on the theories of chemical bond, which have
preceded the Lewis concept. One of the oldest ideas, which in principle talks about
the nature of bonding of atoms is the theory about the atoms—material points
formulated by Rugjer Josip Bošković. Since this theory has been analysed in the
fifth lecture, and because this theory does not include the knowledge about electrons, I will not discuss it here.
J. J. Thomson, who discovered electrons, has proposed that these negatively
charged particles should play the central role in the explanation of the chemical
affinity, i.e. the chemical bond. In his work The Forces between Atoms and
Chemical Affinity, [7] published in Philosophical Magazine, Thomson has established some of the basic concepts about chemical bond: (1) for binding of atoms in
molecules the key role have electrons (Thomson has called them corpuscules);
(2) electrons in atoms are separated in two “layers” of which only the so called
outer electrons contribute to the formation of chemical bond, and the inner electrons remain stable, and bound to the atom; (3) maximal number of outer
(“chemical”) electrons cannot be higher than 8, and it depends on the position of the
element in one of the 8 groups of the Mendeleev periodic system of elements;
(4) chemical bond is formed by pairing of two electrons in such a way that one of
bonding atoms donates its electron to another atom.
This shift of the electron from one to another atom Thomson describes as a
“direction” of the mobile electron from the surface of the first atom to the centre of
the second atom in the molecule as a consequence of the action of the special tube
of force (the term used by Thomson). For instance, carbon atoms in the ethane
molecule are bound in a way that the two atoms direct electrons to each other.
While in the case of ethylene every atom directs two electrons, in acetylene there
12 Limits of Structural Theory
119
second interpretation by Erwin Schrödinger (1887.–1961.) in 1926, and the first
quantum-chemical calculation of the molecule published by Walter Heinrich
Heitler (1904–1981) and Fritz Wolfgang London (1900–1954) [4]. I will argue
that the Lewis theory about the electronic structure of molecules, which has its
origin in chemical reasoning, is conceptually and metaphysically analogous to
physical quantum mechanics that has appeared within the rigorous physical laws of
motion.
As I have demonstrated in previous lectures, chemical scientific methodology is
based on classifications. Creation of the structural theory and periodic system of
elements are the illustrative examples of the effectiveness of this epistemology in
the investigation of the microcosm. Lewis uses the same methodology in building
his theory about the chemical bond starting with chemical classifications: (i) dividing molecules in polar and nonpolar, and (ii) using the Abegg’s octet rule. Pierre
Duhem has argued that the method of classifications is in the relation with a sort of
“natural classification”, and that science oriented to the classification method led
science to form the deeper insight in the nature, than the science that forms only the
theories as its final product [5, 6]. Thus, science has to be oriented to classification.
Perhaps, the development of chemistry is an additional argument for the thesis of
Duhem.
For the beginning, I wish to focus on the theories of chemical bond, which have
preceded the Lewis concept. One of the oldest ideas, which in principle talks about
the nature of bonding of atoms is the theory about the atoms—material points
formulated by Rugjer Josip Bošković. Since this theory has been analysed in the
fifth lecture, and because this theory does not include the knowledge about electrons, I will not discuss it here.
J. J. Thomson, who discovered electrons, has proposed that these negatively
charged particles should play the central role in the explanation of the chemical
affinity, i.e. the chemical bond. In his work The Forces between Atoms and
Chemical Affinity, [7] published in Philosophical Magazine, Thomson has established some of the basic concepts about chemical bond: (1) for binding of atoms in
molecules the key role have electrons (Thomson has called them corpuscules);
(2) electrons in atoms are separated in two “layers” of which only the so called
outer electrons contribute to the formation of chemical bond, and the inner electrons remain stable, and bound to the atom; (3) maximal number of outer
(“chemical”) electrons cannot be higher than 8, and it depends on the position of the
element in one of the 8 groups of the Mendeleev periodic system of elements;
(4) chemical bond is formed by pairing of two electrons in such a way that one of
bonding atoms donates its electron to another atom.
This shift of the electron from one to another atom Thomson describes as a
“direction” of the mobile electron from the surface of the first atom to the centre of
the second atom in the molecule as a consequence of the action of the special tube
of force (the term used by Thomson). For instance, carbon atoms in the ethane
molecule are bound in a way that the two atoms direct electrons to each other.
While in the case of ethylene every atom directs two electrons, in acetylene there
12 Limits of Structural Theory
119