Electronic Configuration of d-block Elements

The elements which lie in between the Group IIA elements and the Group II B elements in the modern periodic table are known as the d block elements. The d-block elements are sometimes also known as the transition elements.

d-block elements

D-block Elements

Electronic configuration of an element is defined as an arrangement of electrons in the orbital. Orbital s, p, d, and f are the four principal atomic orbitals which should be filled according to the number of electrons and the energy level of the orbital. The four orbitals can be arranged according to their energy level as s< p< d< f. According to Aufbau’s principle the lowest energy orbital should be filled first. The s orbital can acquire two electrons whereas p, d and f orbitals can hold 6, 10and 14 electrons respectively. The electronic configuration of first row transition element is shown in the table below:

Atomic number Symbol Electronic  configuration
21 Sc [Ar]3d14s2
22 Ti [Ar]3d24s2
23 V [Ar]3d34s2
24 Cr [Ar]3d54s1
25 Mn [Ar]3d54s2
26 Fe [Ar]3d64s2
27 Co [Ar]3d74s2
28 Ni [Ar]3d84s2
29 Cu [Ar]3d104s1
30 Zn [Ar]3d104s2

1st series

So we generalize the outer configuration of first row transition elements as 4s2 3dn. But from the above table we can see that chromium and copper do not follow this pattern. This is because of very little energy difference between the 3d shell and 4s shell. It is experimentally found that half and completely filled sets of orbitals are more stable. In the case of chromium and copper the energy difference between the orbitals is very less so it is unable to prevent the electrons entering in the d shell. The electronic configuration of d-block element in the modern periodic table can be written as shown in the table below:-

Atomic number Symbol Configuration
39 Y 5s2 4d1
40 Zr 5s24d2
41 Nb 5s14d4
42 Mo 5s14d5
43 Tc 5s14d6
44 Ru 5s14d7
45 Rh 5s14d8
46 Pd 5s04d10
47 Ag 5s14d10
48 Cd 5s24d10

2nd series

Atomic number Symbol Configuration
57 La 6s25d1
72 Hf 6s25d2
73 Ta 6s25d3
74 W 6s25d4
75 Re 6s25d5
76 Os 6s25d6
77 Ir 6s25d7
78 Pt 6s15d9
79 Au 6s15d10
80 Hg 6s25d10

3rd series

Atomic  number Symbol Configuration
89 Ac 7s26d1
104 Rf 7s26d2
105 Db 7s26d3
106 Sg 7s26d4
107 Bh 7s26d5
108 Hs 7s26d6
109 Mt 7s26d7
110 Ds 7s26d8
111 Rg 7s26d10
112 Uub 7s26d10

 4th series

Zn, Cd and Hg have their orbitals completely filled both in their ground state and in their common oxidation states and is represented as (n-1) d10 ns2. So, they are not referred to as transition elements.

This information on electronic configuration of d-block elements is described briefly. Read more about S-Block Elements.

Practise This Question

Colour of actinides depends on number of electrons present in