Physical Properties of d block elements

Oxidation states and hence, are not regarded as transition metals. The d-block occupies the larger middle section flanked by s-block and p-block. Lattice structures of transition elements are formed by the repetition of unit cells. The lattice structure of transition elements or metals has closed 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 geometry size, shape, structure, and spatial structure of unit cells. Physical properties of d block elements contain 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 orbital or completely filled full orbital.

Transition elements or d block elements 

The d block, also called transition metals, is found between the s block and p block elements. The last electron of these elements enters the penultimate d subshell and hence has been named block elements. They are called transition elements because they show a transition from highly reactive ionic metals in the s block to non-covalent metals in the p block.

Characteristic physical properties of transition elements 

The general characteristic of d-block elements are:

• The transition elements have very high densities compared to the metal of groups I and II(s-block).
• d-block elements form compounds that are generally paramagnetic.
• 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, nitrogen, etc.
• Most transition metals such as Mn, Ni, Co, Cr, V, etc., and their compounds have been used as catalysts. 
• Transition elements have a high melting point because they have high ionisation enthalpy.
• Except for mercury which is liquid at room temperature, other transition elements have a typical metallic structure.
• Except for some transition metals, all the transition metals have typical metallic properties such as lustre surface, hardness, malleability, ductility, etc. Metallic bonds are formed because of the interaction between electrons present in the outermost shell of a transition atom.

The lattice structure of transition elements 

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

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

Physical properties of transition elements 

1. Atomic and ionic radii 

The atomic radii in a transition series decrease from left to right due to an increase in the nuclear charge. However, the decrease in atomic radii is minimal and non-uniform. It decreases from group-3 to group-10 and again increases towards the end of the series due to inter electronic repulsions among (n-1)d-electrons.

On moving down, the group atomic radii of transition elements increase. Third transition series elements (except first member La) have nearly the same atomic radii as that of second transition series elements due to lanthanoid contraction.

2. Ionisation enthalpy 

Ionisation enthalpies increase along with a given transition series due to increased nuclear charge. Ionisation enthalpies also increase down the group in a series. 5d series have higher ionisation enthalpy than 3d and 4d series but irregularity is observed in ionisation enthalpies of 3d and 4d series.

3. Metallic character 

Except for mercury, all transition elements have a typical metallic structure (hcp, ccp, or bcc) and show all the properties of metals. The metallic character is due to low ionisation enthalpies and the number of vacant orbitals in the outermost shell. The greater the number of unpaired d-electrons, the greater is the number of bonds, and therefore, greater is the strength of these bonds. Hence, hardness and enthalpy of atomisation increase with the increase in several unpaired electrons and due to high metallic character transition elements have a high melting point.

4. Magnetic properties 

Magnetic properties are present in transition elements because of unpaired electrons which are present in transition elements.

Most of the transition metals ions and compounds formed by these metal ions are paramagnetic, and they are attracted towards the magnetic field but Zn2+is diamagnetic.

Conclusion 

In books, we have considered the physical properties of transition metals as the main regularities of adsorption and catalysis.

Physical properties play an important role in identifying the transition elements from the list of elements. The lattice structure of transition elements makes the study of transition elements easy and understandable for the students.

The d block elements have high melting and boiling point, typical metallic properties and also form coloured compounds with other elements of the periodic table. In the end, we conclude that the physical properties of transition elements are a very important part of the periodic table as it makes the study and discovery of new elements easy.

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