Chemistry Reference
In-Depth Information
Fig. 11.4 Mendeleev
'
s
Natural System
of the elements from 1870
between Cr and Mn, on the one side, and Cu and Zn, on the other, so as to form the
following
transition series
:”
60
Cr
¼
52
Mn
¼
55
Fe
¼
56
Co
¼
59
Ni
¼
59
Cu
¼
63
Zn
¼
65
Two other triads of transition metals could be discerned in the
Natural System
: the
elements Ru, Rh and Pd, on the one hand, and Os, Ir and Pt on the other (Fig.
11.4
).
Mendeleev emphasised that “the members of this group [
] resemble one
another to the same extent as the corresponding members of the even series”,
61
with the only difference that they constituted three
primary groups
, instead of
secondary groups
as in the case of the elements from the groups I-VII. Notice
also that these groups were
horizontally
orientated, just as Mendeleev had predicted
back in 1869, when he said that perhaps the system of elements would have to be
changed “such that in certain parts of the system the similarity between members of
the horizontal rows [i.e. primary elements] will have to be considered, but in other
parts, the similarity between members of the vertical columns [i.e. secondary
elements].”
62
One can conclude that Mendeleev was aided significantly by his construction of
the short form table in defining the transition metals more clearly than before as
those elements which connected the even and odd series.
...
60
Loc. cit. Emphasis added.
61
Loc. cit.
62
Mendeleev (1869b/t), op. cit., p. 31. (note 16)
