“two-dimensional”; in one direction, it is classification of substances that is based
on the Lewis-type structures of their molecules with fixed electron pairs between
atoms, and in perpendicular direction it is the classification of chemical reactions
that is based on the movement of these electron pairs.
These two classifications are new challenge not only for further research, but
also for the teaching methods in chemistry. Appearance of two ”perpendicular”
systematics in science denotes the difficulty for education. In modern teaching of
chemistry these methodical paradoxes are not solved, and they cannot be removed.
Till the early sixties, the organic chemistry textbooks were based on the classification of the types of substances. That means that in these textbooks we can find
chapters about, for example, alcohols, ethers, aldehydes, amides, etc. Thus, in these
textbooks any information about the important properties of particular organic
compound can easily be found. However, if you wish to propose the series of
reactions by which the new chemical compound can be synthesised, these reactions
are difficult to find in this textbook, because they are dispersed through various
chapters.
New approach to education in organic chemistry has appeared in 1959 with the
textbook written by George S. Hammond (1921–2005) and Donald J. Cram
(1919.–2001.). Later, in the new edition, 1970, the third author James B. Hendrickson joined this book [14] (Hendrickson, Cram, Hammond, 1970). In this
textbook organic chemistry is classified by types of chemical reactions in accordance with the works of Ingold and Hughes, and not by types of chemical compounds. There are chapters entitled as nucleophilic substitution, additions,
eliminations, molecular rearrangements, etc. The advance and the scope of this
textbook is that students are well educated in chemical synthesis, in designing of
novel molecules, new substances, because it develops the skill for combining
typical chemical reactions. However, the information about particular organic
compounds and their properties is in this textbook almost unreachable because it is
scattered all over the entire contents.
The conclusion is interesting. If we decide to receive one kind of information
(for instance about particular substance), another kind of information (how to
combine chemical reactions to synthesize the target compound) is unavailable. This
is a sort of the principle of exclusiveness, which could also be applied out of
chemistry, even out of science, and which tells us that the picture of the world, or
perhaps the picture of the Universe as itself, depends on the decision of the
observer!
There are many analogies for this principle. The subject decides what to observe
with the awareness that by this observation some other information vanishes.
Practical example is represented in the following photos. By photographing the car
in movement with very short exposition on camera, say 1/1000 seconds, the photo
provides information about the exact position of the car (left photo), but from this
photograph no information about the speed of this car is available. On the other
hand, if we take the photo with the long exposition, say two seconds, we get the
picture (right photo) from which we cannot get information about the position of the
car. However, from the smear on the photo we can (knowing the exposition)
12 Limits of Structural Theory
133
on the Lewis-type structures of their molecules with fixed electron pairs between
atoms, and in perpendicular direction it is the classification of chemical reactions
that is based on the movement of these electron pairs.
These two classifications are new challenge not only for further research, but
also for the teaching methods in chemistry. Appearance of two ”perpendicular”
systematics in science denotes the difficulty for education. In modern teaching of
chemistry these methodical paradoxes are not solved, and they cannot be removed.
Till the early sixties, the organic chemistry textbooks were based on the classification of the types of substances. That means that in these textbooks we can find
chapters about, for example, alcohols, ethers, aldehydes, amides, etc. Thus, in these
textbooks any information about the important properties of particular organic
compound can easily be found. However, if you wish to propose the series of
reactions by which the new chemical compound can be synthesised, these reactions
are difficult to find in this textbook, because they are dispersed through various
chapters.
New approach to education in organic chemistry has appeared in 1959 with the
textbook written by George S. Hammond (1921–2005) and Donald J. Cram
(1919.–2001.). Later, in the new edition, 1970, the third author James B. Hendrickson joined this book [14] (Hendrickson, Cram, Hammond, 1970). In this
textbook organic chemistry is classified by types of chemical reactions in accordance with the works of Ingold and Hughes, and not by types of chemical compounds. There are chapters entitled as nucleophilic substitution, additions,
eliminations, molecular rearrangements, etc. The advance and the scope of this
textbook is that students are well educated in chemical synthesis, in designing of
novel molecules, new substances, because it develops the skill for combining
typical chemical reactions. However, the information about particular organic
compounds and their properties is in this textbook almost unreachable because it is
scattered all over the entire contents.
The conclusion is interesting. If we decide to receive one kind of information
(for instance about particular substance), another kind of information (how to
combine chemical reactions to synthesize the target compound) is unavailable. This
is a sort of the principle of exclusiveness, which could also be applied out of
chemistry, even out of science, and which tells us that the picture of the world, or
perhaps the picture of the Universe as itself, depends on the decision of the
observer!
There are many analogies for this principle. The subject decides what to observe
with the awareness that by this observation some other information vanishes.
Practical example is represented in the following photos. By photographing the car
in movement with very short exposition on camera, say 1/1000 seconds, the photo
provides information about the exact position of the car (left photo), but from this
photograph no information about the speed of this car is available. On the other
hand, if we take the photo with the long exposition, say two seconds, we get the
picture (right photo) from which we cannot get information about the position of the
car. However, from the smear on the photo we can (knowing the exposition)
12 Limits of Structural Theory
133