As a basis for the construction of the periodic system, Mendeleev has not used
only the ratios of masses and valences. Rather, he has considered other chemical
and physical properties. One of the most important property is the formation of
seven different types of oxides of elements, such as M 2 O, MO, M 2 O 3 , MO 2 , M 2 O 5 ,
MO 3 and the group MO 4 - in particular compounds (perchlorates, permanganates,
etc.). In his revised table of elements Mendeleev has proposed the classification of
elements in seven groups (columns in the Table) with the addition of the group of
noble gasses, and in six periods (rows in the Table) [7].
The scientific value of the periodic system, or the possible periodic law, was in
its ability to predict properties of elements, which were unknown at that time. Some
places in the periodic table were remained empty waiting for the discovery of new
elements. Mendeleev has called them Eka-boron, Eka-aluminium, and Eka-silicon.
After the discovery of elements scandium, gallium and germanium, their basic
properties were in high agreement with those predicted from their position in the
periodic table. However, it must be mentioned that Mendeleev has anticipated the
properties of some other unknown elements, but with wrong prediction of their
properties [8]. Does it mean that Mendeleev periodic law should be, in accordance
with Popper criteria, rejected from science? This represents an additional example
for the discussion about the demarcation between good and wrong science (vide
infra).
Fundamental principles of structural theory of microcosmos were emerged from
chemical investigations, i.e. from the epistemology based on the method of analogy
and classification, [9] much more than from the use of logical manipulations. The
building principle in modern textbooks, by which the periodic table can be constructed from the electronic configurations of elements is often in a wrong way
explained as the origin of the theory of periodicity of properties of elements.
Representation of electronic structures of atoms of elements is very radical
approximation [10]. The periodic system of elements is originally chemical concept, not the consequence of the discovery of electronic structures of atoms.
As I have argued, Dumas has used analogy as the method in the comparative
classification of organic molecules and chemical elements. Now I wish to explain
how the conceptual systems such as theory of types and periodic law can be used
more generally for the clarification of metaphysical meaning of the notions quality
and quantity. The representative models for this is the periodic system of elements.
Its periods (rows) are organized according to the increase of relative atomic masses
(in Mendeleev version). This principle is exclusively quantitative, because it is
based on the numerical physical values. However, the groups (columns) are created
by the type of compounds (for instance, oxides) that an element can form. If
elements E form oxides EO 2 , then all of them belong to the same group. Elements
witin the same group are analogous, and they are classified not on the quantitative,
but by using the qualitative criterion. Thus, the periodic table is a two-dimensional
classification system in which abscise (period) is a measure for quantity, and the
ordinate (the eight groups of elements) is the representation for quality.
10 Systematization, Classification, Structure, and Elements
101
only the ratios of masses and valences. Rather, he has considered other chemical
and physical properties. One of the most important property is the formation of
seven different types of oxides of elements, such as M 2 O, MO, M 2 O 3 , MO 2 , M 2 O 5 ,
MO 3 and the group MO 4 - in particular compounds (perchlorates, permanganates,
etc.). In his revised table of elements Mendeleev has proposed the classification of
elements in seven groups (columns in the Table) with the addition of the group of
noble gasses, and in six periods (rows in the Table) [7].
The scientific value of the periodic system, or the possible periodic law, was in
its ability to predict properties of elements, which were unknown at that time. Some
places in the periodic table were remained empty waiting for the discovery of new
elements. Mendeleev has called them Eka-boron, Eka-aluminium, and Eka-silicon.
After the discovery of elements scandium, gallium and germanium, their basic
properties were in high agreement with those predicted from their position in the
periodic table. However, it must be mentioned that Mendeleev has anticipated the
properties of some other unknown elements, but with wrong prediction of their
properties [8]. Does it mean that Mendeleev periodic law should be, in accordance
with Popper criteria, rejected from science? This represents an additional example
for the discussion about the demarcation between good and wrong science (vide
infra).
Fundamental principles of structural theory of microcosmos were emerged from
chemical investigations, i.e. from the epistemology based on the method of analogy
and classification, [9] much more than from the use of logical manipulations. The
building principle in modern textbooks, by which the periodic table can be constructed from the electronic configurations of elements is often in a wrong way
explained as the origin of the theory of periodicity of properties of elements.
Representation of electronic structures of atoms of elements is very radical
approximation [10]. The periodic system of elements is originally chemical concept, not the consequence of the discovery of electronic structures of atoms.
As I have argued, Dumas has used analogy as the method in the comparative
classification of organic molecules and chemical elements. Now I wish to explain
how the conceptual systems such as theory of types and periodic law can be used
more generally for the clarification of metaphysical meaning of the notions quality
and quantity. The representative models for this is the periodic system of elements.
Its periods (rows) are organized according to the increase of relative atomic masses
(in Mendeleev version). This principle is exclusively quantitative, because it is
based on the numerical physical values. However, the groups (columns) are created
by the type of compounds (for instance, oxides) that an element can form. If
elements E form oxides EO 2 , then all of them belong to the same group. Elements
witin the same group are analogous, and they are classified not on the quantitative,
but by using the qualitative criterion. Thus, the periodic table is a two-dimensional
classification system in which abscise (period) is a measure for quantity, and the
ordinate (the eight groups of elements) is the representation for quality.
10 Systematization, Classification, Structure, and Elements
101