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Question
Compare the general characteristics of the first series of the transition metals with those of the second and third series metals in the respective vertical columns. Give special emphasis on the following point:
Electronic configurations
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Solution
The electronic configurations of the elements of the same group are generally similar.
The first transition series shows two exceptions:
Cr = 3d5 4s1 and Cu = 3d10 4s1
The second series shows more exceptions:
Mo (42) = 4d5 5s1, Tc (43) = 4d6 5s1, Ru (44) = 4d7 5s1, Rh (45) = 4d8 5s1, Pd (46) = 4d10 5s0, Ag (47) = 4d10 5s1
Similarly, the third series shows exceptions:
W (74) = 5d4 6s1, Pt (78) = 5d9 6s1, and Au (79) = 5d10 6s1
The first transition series gradually fills 3d-orbitals, whereas the second and third transition series gradually fill 4d-orbitals and 5d-orbitals, respectively. Therefore, in many cases in the horizontal series, the electronic configurations of the three series are not the same.
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