d-Block Elements and Their Properties

The d- block elements and their properties are crucial topics in chemistry. 

The d-block elements are present in the centre of the periodic table, starting from group number 3 to group number 12. They are so named because the last electrons go to the d-orbital of the penultimate shell. 

The filling of 3d, 4d, 5d or 6d orbitals relates to the four series of the d-block:

3d Series

[ Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn]

4d Series

[Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Ag, Cd]

5d Series

[La, Hf, Ta, W, Re, Os, Ir, Pt, Au, Hg]

6d Series

Incomplete

Transition Elements

Transition elements are nothing but d-block elements; they have partly-filled d-orbitals. 

These elements are transition elements due to their properties that fall in the middle of non-metallic P-block elements and highly reactive metallic s-block elements. Transition elements range from 21Sc to 112Cn, not including lanthanides and actinides. We can define lanthanide and actinides as the inner transition elements.

Thus, the d-block elements show a transition from metals to nonmetals within the periodic table. Therefore, we can define the transition elements as the elements in the middle of the s-block and p-block elements in the modern periodic table.

d-block Elements Properties

The basic properties of d-block or transition elements are as follows:

• Transition elements represent variable oxidation numbers as well as multiple valences. For example, Ti shows +3, +4 valencies, Cr shows +2, +3, +4, +6 valencies, etc.
• Transition elements produce coordination complexes or coordination compounds.
• Transition metals produce colourful compounds.
• Transition metals represent high melting and boiling points at the same time.
• Transition elements come with higher densities.
• Transition elements represent catalytic properties.
• Transition elements usually create stable complexes.
• Transition elements come with a large charge and radius ratio.

Series of d-block or Transition Elements

As mentioned earlier, we can distribute d-block into the following four series:

• 1st Transition Series: 

This series comprises elements from Sc to Zn in the fourth period of the periodic table.

• 2nd Transition Series: 

This series comprises elements from Y to Cd in the fifth period of the periodic table.

• 3rd Transition Series: 

This series comprises elements from Hf to Hg in the sixth period of the periodic table. Moreover, the sixth period also has lanthanides which are part of the inner transition elements.

• 4th Transition Series Elements: 

This series comprises elements from Rf to Cn in the seventh period of the periodic table. Moreover, the seventh period also has actinides which belong to the inner transition elements.

Location of Transition Elements in the Periodic Table

We can locate the transition or d-block elements in the periodic table after the s-block and before the p-block elements. They initiate from the 4th period of the long type of periodic table.

Moreover, these transition elements can be of the non-typical and typical types. 

The elements of the II B group (Zn, Cd, and Hg) have a completely filled (n-1) d-subshell; we cannot merge them into the d-block. However, they show properties, such as ligation – for instance, in ammonia, amines, and halide particles. Therefore, the periodic table places them alongside the d-block elements.

Furthermore, the elements of group III-A (Sc, Y, La, and Ac) are different from those of d-block. Nevertheless, they do not have a completely filled (n-1)d subshell. Therefore, these elements locate themselves around the elements of d-block.

Melting and Boiling Points

The melting and boiling points of the d-block or transition elements, except Cd and Hg, are very high than the s-block and p-block elements. 

Moreover, the melting and boiling points initially rise, go through the highest value and gradually reduce across the transition series. The highest point occurs near the centre of the series.  

Magnetic Properties

The maximum of the transition elements and compounds show paramagnetism. In addition, in transition elements, paramagnetism decreases along the series. However, the centre of the series has a high level of paramagnetism. 

The BM units define paramagnetism.

Oxidation States

Mostly, the transition elements show multiple and dissimilar states of oxidation. It means that they serve inconstant valency in their compounds.

Conclusion

This study material notes on classification of elements discusses d-block elements and their properties. They provide comprehensive information on the definition, characteristics, and periodic table position of these elements. 

It also explores the properties of melting point, boiling point, magnetism, and oxidation in brief. The melting and boiling points and magnetism decreases along the series, while there is considerable variance in oxidation states of the d-block elements.