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The d-and f-Block Elements

Introduction to Transition Elements

Position in the Periodic Table

  • Their position is in between s- and p- block elements.

  • There are four rows of transition elements − 3d, 4d, 5d, and 6d. The fourth row of 6d is still incomplete.

Electronic Configuration

  • General outer electronic configuration is (n −1)d1−10 ns1−2.

  • But this generalization has several exceptions as there is very little difference in energy between (n − 1)d and ns orbitals. For example, Cr has electronic configuration 3d5 4s1 instead of 3d4 4s2. Cu has electronic configuration 3d10 4s1 instead of 3d9 4s2.

  • Outer electronic configurations of the transition elements in the ground state are listed in the following tables:

1st series

2nd series

Element

Atomic number

Outer electronic configuration

Element

Atomic number

Outer electronic configuration

Sc

21

3d14s2

Y

39

4d15s2

Ti

22

3d24s2

Zr

40

4d25s2

V

23

3d34s2

Nb

41

4d45s1

Cr

24

3d54s1

Mo

42

4d55s1

Mn

25

3d54s2

Tc

43

4d65s1

Fe

26

3d64s2

Ru

44

4d75s1

Co

27

3d74s2

Rh

45

4d85s1

Ni

28

3d84s2

Pd

46

4d105s0

Cu

29

3d104s1

Ag

47

4d105s1

Zn

30

3d104s2

Cd

48

4d105s2

3rd series

4th series

Element

Atomic number

Outer electronic configuration

Element

Atomic number

Outer electronic configuration

La

57

5d16s2

Ac

89

6d17s2

Hf

72

5d26s2

Rf

104

6d27s2

Ta

73

5d36s2

Db

105

6d37s2

W

74

5d46s2

Sg

106

6d47s2

Re

75

5d56s2

Bh

107

6d57s2

Os

76

5d66s2

Hs

108

6d67s2

Ir

77

5d76s2

Mt

109

6d77s2

Pt

78

5d96s1

Ds

110

6d87s2

Au

79

5d106s1

Rg

111

6d107s1

Hg

80

5d106s2

Uub

112

6d107s2

  • Zn, Cd, and Hg are not regarded as transition elements.

  • Reason − The orbitals of these elements are completely-filled. [Electronic configuration is (n − 1) d10 ns2]

  • Ions of configuration d1−9 have similar magnetic and electronic properties.

  • Elements with partially-filled d-orbitals exhibit certain characteristic properties such as showing a variety of oxidation states, formation of coloured ions, and formation of complex with a variety of ligands.

  • They and their compounds have catalytic property and are paramagnetic in nature.

Position in the Periodic Table

  • Their position is in between s- and p- block elements.

  • There are four rows of transition elements − 3d, 4d, 5d, and 6d. The fourth row of 6d is still incomplete.

Electronic Configuration

  • General outer electronic configuration is (n −1)d1−10 ns1−2.

  • But this generalization has several exceptions as there is very little difference in energy between (n − 1)d and ns orbitals. For example, Cr has electronic configuration 3d5 4s1 instead of 3d4 4s2. Cu has electronic configuration 3d10 4s1 instead of 3d9 4s2.

  • Outer electronic configurations of the transition elements in the ground state are listed in the following tables:

1st series

2nd series

Element

Atomic number

Outer electronic configuration

Element

Atomic number

Outer electronic configuration

Sc

21

3d14s2

Y

39

4d15s2

Ti

22

3d24s2

Zr

40

4d25s2

V

23

3d34s2

Nb

41

4d45s1

Cr

24

3d54s1

Mo

42

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