The d-block occupies the larger middle section flanked by the s-block and p-block.

The lattice structures of transition elements are formed by the repetition of unit cells.

The lattice structure of transition elements or metals has closely packed and highly symmetrical structures such as body-centred cubic, face-centred cubic and hexagonal close packing. 

The properties of the lattice structure of transition elements depend on geometric size, shape, structure and spatial structure of unit cells. Physical properties of d-block elements include alloy formation, high melting point, density, atomic and ionic radii and typical metallic properties. 

The electronic configuration of d-block elements is represented by (n-1) (d0-10) n(s1-2). D- block elements can find stability in half-filled orbitals or completely filled full orbitals.

Properties of d-block elements

D-block elements mostly occur between groups 3 and 12 on the modern periodic table. They are a total of 40 elements, with ten columns and four rows located on the modern periodic table. They are referred to as the ‘d-block elements’ due to the electron configurations filling in the d shell in the increased energy level. 

A change from most electropositive s-block elements to the least electropositive p-block elements is observed throughout the D-block elements. Starting from the fourth period, they are arranged in the form of four distinct 3d, 4d, 5d and 6d series. 

D-block elements are important because soft d-block elements occur as sulphide minerals, whereas hard metals occur as oxides.

Characteristics of d-block elements 

The general characteristics of d-block elements are:

• The transition elements have very high densities as compared to the metals of groups I and II (s-block).
• D-block elements form compounds that are generally paramagnetic but exceptions are present.
• D-block elements are used to make alloys with other metals.
• D-blocks elements have a large size; that’s why they form interstitial compounds with elements such as hydrogen, boron, carbon, and nitrogen.
• Except for mercury, which is liquid at room temperature, other transition elements have a typical metallic structure.
• We know that except for some transition metals, all the d-block elements are important because they have typical metallic properties such as lustrous surfaces, hardness, malleability, ductility, and so on. Metallic bonds are formed because of the interaction between electrons that are present in the outermost shell.

Magnetic properties of d-block elements

• Most of the transition metals are paramagnetic due to the presence of unpaired electrons in the (n-1)d-orbitals. Hence, they are easily attracted by the magnetic field.
• As the number of unpaired electrons increases from 1 to 5, the magnetic movement and paramagnetic nature of the element also increases.
• The transition elements that have paired electrons are diamagnetic in nature and tend to get repelled by the magnetic field.
• Cobalt and nickel show high paramagnetism, where they attain permanent magnetic movements. Hence, they are referred to as ferromagnetic.
• Similarly, an element that comprises entirely paired electrons demonstrates diamagnetism. They tend to get repelled by the magnetic field.

Conclusion 

The higher the number of the unpaired electrons in an element’s electron configuration, the more the magnetic behaviour. It is normally observed that the transition element ion exhibits paramagnetic behaviour and is attracted easily by the magnetic field. The position of the first transition series lies in the 4th, 5th, 6th, and 7th groups. It comprises a coloured effect due to inward d-d transfers. The d-block elements’ properties in which magnetic properties are included can be determined with theories such as quantum mechanics.

It is difficult to explain whether a particular compound is paramagnetic or not, without any clue and facts. So, there is a requirement to make the electronic configuration and observe if the configuration directs to paired and unpaired electrons. If it holds the unpaired electrons in (n-1)d shells, then its magnetic behaviour is concluded to be either paramagnetic or ferromagnetic.