d-block elements are those in which the last electron enters the d-orbital of the valence shell. Here, we will discuss about the d-block elements.

What are d-block Elements

1. These are elements in which last electron enters any one of the 5 orbitals of their respective penultimate shell.
2. General outer electronic configuration : (n-1) d^1-10 ns ^0-2 where n= 4 – 7
3. There are 10 groups from group 3 to group 12
4. d-block have the properties which lies in between s-block and p-block block elements. Therefore, they are known as transition elements.

Transition series of d-block

1. The first transition series forms 4th period. It contains 10 elements from Scandium to Zinc ( ₂₁Sc – ₃₀ Zn ). Here, is the progressive filling of 3d orbitals.
2. The second transition series forms 5th period. It contains 10 elements from Ytterium to Cadmium ( ₃₉Y – ₄₈Cd ). Here, is the progressive filling of 4d orbitals.
3. The Third transition series forms 6th period. It contains 10 elements from Lanthanum, and Hafnium to Mercury ( ₇₂Hf-₈₀Hg ). Here, is the progressive filling of 5d orbitals.
4. The fourth transition series forms 7th period. It contains 10 elements from actinium and Rutherfordium (104) to (112) Copernicium. Here, is the progressive filling of 6d orbitals.
5. There are groups 3 to 12 in which the last electron enters the d orbitals of their respective penultimate shells.
6. Therefore, there are 40 d elements in the periodic table.

General characteristics of d-block elements

1. These elements are hard, malleable and ductile metals with high melting and boiling points.
2. These metals show IE between s and p block elements.
3. They show variable Oxidation state.
4. They form ionic as well as covalent compounds.
5. These compounds are coloured and paramagnetic in nature.
6. Transition metals form co-ordination complexes.
7. There are 3 exceptions which do not behave as transition elements. Zn, Cd and Hg has EC (n-1)d¹⁰ ns²
8. Most of the transition elements form alloys.
9. They are good conductor of heat and electricity.
10. Their compounds acts as catalysts.

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