Notes On d-Block: Position And Electronic Configuration - CBSE Class 12 Chemistry

D-block elements are the collective name for the groups 3 to 12, in which the d-orbitals are progressively filled in each of the four long periods.

As the d-block elements lies between the s and p block elements, they are also referred to as the transition elements.

There are mainly three series of transition elements. They are

3d series: This includes the elements from scandium to zinc.

4d series: This includes the elements from yttrium to cadmium

5d series: This includes the elements from lanthanum to mercury.

The fourth series, the 6d series, which begins with actinium, is still incomplete.

General electronic configuration:

(n-1) d1-10ns1-2.

The atoms of the d-block elements try to fill their available d-orbitals either partially with five electrons, or completely with ten electrons whenever possible. This is due to the fact that half-filled or completely filled orbitals impart greater stability to an atom.

Element Outer Electronic Configuration
Scandium (Sc)   3d1 4s2
Titanium (Ti)   3d2 4s2
Vanadium (V)   3d3 4s2
Chromium (Cr)   3d5 4s1
Manganese (Mn)   3d5 4s2
Iron (I)   3d6 4s2
Cobalt (Co)   3d7 4s2
Nickel (Ni)   3d8 4s2
Copper (Cu)   3d10 4s1
Zinc (Zn)   3d10 4s2



Configurations of chromium and copper in the 3d series:

Chromium, for example, has a configuration of 3d5 4s1 instead of the expected 3d4 4s2. Copper, on the other hand, has an electronic configuration of 3d 10 4s1 instead of 3d9 4s2.

The properties of transition elements depend largely on their electronic -configurations. Thus, with partly filled d orbitals.

The precious metals, like gold, platinum and silver, and industrially important metals like iron, copper and titanium, form part of the transition elements.

Summary

D-block elements are the collective name for the groups 3 to 12, in which the d-orbitals are progressively filled in each of the four long periods.

As the d-block elements lies between the s and p block elements, they are also referred to as the transition elements.

There are mainly three series of transition elements. They are

3d series: This includes the elements from scandium to zinc.

4d series: This includes the elements from yttrium to cadmium

5d series: This includes the elements from lanthanum to mercury.

The fourth series, the 6d series, which begins with actinium, is still incomplete.

General electronic configuration:

(n-1) d1-10ns1-2.

The atoms of the d-block elements try to fill their available d-orbitals either partially with five electrons, or completely with ten electrons whenever possible. This is due to the fact that half-filled or completely filled orbitals impart greater stability to an atom.

Element Outer Electronic Configuration
Scandium (Sc)   3d1 4s2
Titanium (Ti)   3d2 4s2
Vanadium (V)   3d3 4s2
Chromium (Cr)   3d5 4s1
Manganese (Mn)   3d5 4s2
Iron (I)   3d6 4s2
Cobalt (Co)   3d7 4s2
Nickel (Ni)   3d8 4s2
Copper (Cu)   3d10 4s1
Zinc (Zn)   3d10 4s2



Configurations of chromium and copper in the 3d series:

Chromium, for example, has a configuration of 3d5 4s1 instead of the expected 3d4 4s2. Copper, on the other hand, has an electronic configuration of 3d 10 4s1 instead of 3d9 4s2.

The properties of transition elements depend largely on their electronic -configurations. Thus, with partly filled d orbitals.

The precious metals, like gold, platinum and silver, and industrially important metals like iron, copper and titanium, form part of the transition elements.

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