The dand fBlock 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)d^{1−10}^{ }ns^{1−2}.

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 3d^{5} 4s^{1} instead of 3d^{4}^{ }4s^{2}. Cu has electronic configuration 3d^{10} 4s^{1} instead of 3d^{9} 4s^{2}.

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

1^{st} series
2^{nd} series
Element
Atomic number
Outer electronic configuration
Element
Atomic number
Outer electronic configuration
Sc
21
3d^{1}4s^{2}
Y
39
4d^{1}5s^{2}
Ti
22
3d^{2}4s^{2}
Zr
40
4d^{2}5s^{2}
V
23
3d^{3}4s^{2}
Nb
41
4d^{4}5s^{1}
Cr
24
3d^{5}4s^{1}
Mo
42
4d^{5}5s^{1}
Mn
25
3d^{5}4s^{2}
Tc
43
4d^{6}5s^{1}
Fe
26
3d^{6}4s^{2}
Ru
44
4d^{7}5s^{1}
Co
27
3d^{7}4s^{2}
Rh
45
4d^{8}5s^{1}
Ni
28
3d^{8}4s^{2}
Pd
46
4d^{10}5s^{0}
Cu
29
3d^{10}4s^{1}
Ag
47
4d^{10}5s^{1}
Zn
30
3d^{10}4s^{2}
Cd
48
4d^{10}5s^{2}

…
3^{rd} series
4^{th} series
Element
Atomic number
Outer electronic configuration
Element
Atomic number
Outer electronic configuration
La
57
5d^{1}6s^{2}
Ac
89
6d^{1}7s^{2}
Hf
72
5d^{2}6s^{2}
Rf
104
6d^{2}7s^{2}
Ta
73
5d^{3}6s^{2}
Db
105
6d^{3}7s^{2}
W
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