General Properties of d-Block Elements: Have you ever wondered why iron and steel are used in making tools, utensils, vehicles, bridges, and many more things around us?

We come across many transition elements on a daily basis. Transition elements can be found in a wide range of useful items, including kitchen cutlery, ships, and jewellery. Iron and titanium are the most abundant transition elements.

In this article, we will explore in detail the general characteristics and uses of the d-block elements.

Introduction: General Properties of d-Block Elements

The elements that have an incompletely filled d-subshell in their ground state or most stable oxidation state are known as transition elements. The \(\left( {{\rm{n}} – 1} \right)\,{\rm{d}}\) subshell is included in the partially filled subshells. Although group \(12\) metals do not have partially filled \(\left( {{\rm{n}} – 1} \right)\,{\rm{d}}\)-orbitals, their chemistry is very similar to that of the preceding groups, so they are classified as d block elements.

These elements typically have metallic properties such as malleability and ductility, high electrical and thermal conductivities, and good tensile strength.

d-Block Elements

The Periodic Table’s \({\rm{d}}\) -block contains the elements of groups \(3-12,\) in which the d-orbitals are gradually filled. The elements are divided into three series: 3d-series (\({\rm{Sc}}\) to \({\rm{Zn}}\)), \({\rm{4d}}\) -series (\({\rm{Y}}\) to \({\rm{Cd}}\)), and \({\rm{5d}}\) -series (\({\rm{La}}\) to \({\rm{Hg}}\) omitting \({\rm{Ce}}\) to \({\rm{Lu}}\)). The fourth \({\rm{6d}}\) -series, beginning with \({\rm{Ac,}}\) also includes elements ranging from \({\rm{Rf}}\) to \({\rm{Cn}}{\rm{.}}\)

The non-typical transition elements are \({\rm{II – B}}\) group elements such as \({\rm{Zn,}}\) \({\rm{Cd,}}\) and \({\rm{Hg}}\) and \({\rm{III – B}}\) group elements such as \({\rm{Sc, Y, La,}}\) and \({\rm{Ac,}}\) while the remaining transition elements are typical elements.

General Characteristics of d-Block Elements

Because of the close proximity of comparable electronic configurations of the peripheral shell, each element of the \({\rm{d}}\) -block exhibits comparable properties. \({\rm{n}}{{\rm{s}}^{\rm{2}}}\) is the peripheral shell configuration. The general characteristic of d-block elements are as follows:

Electronic Configuration

The general electronic configuration of d-block elements is \(\left( {{\rm{n – 1}}} \right){{\rm{d}}^{{\rm{1 – 10}}}}{\rm{n}}{{\rm{s}}^{{\rm{1 – 2}}}}{\rm{.}}\) These elements can find stability in both half-filled and fully filled d orbitals.
1. The electronic configuration for transition elements in period \(4\) is \(\left[ {{\rm{Ar}}} \right]{\rm{\;4}}{{\rm{s}}^{{\rm{1 – 2}}}}{\rm{3}}{{\rm{d}}^{{\rm{1 – 10}}}}{\rm{.}}\)
2. The electronic configuration for transition elements in period \(5\) is \(\left[ {{\rm{Kr}}} \right]{\rm{\;5}}{{\rm{s}}^{{\rm{1 – 2}}}}{\rm{4}}{{\rm{d}}^{{\rm{1 – 10}}}}{\rm{.}}\)
3. The electronic configuration for transition elements in period \(6\) is \(\left[ {{\rm{Xe}}} \right]{\rm{\;6}}{{\rm{s}}^{{\rm{1 – 2}}}}{\rm{4}}{{\rm{f}}^{{\rm{14}}}}{\rm{5}}{{\rm{d}}^{{\rm{1 – 10}}}}{\rm{.}}\)
These three series of elements are determined by the \(\left( {{\rm{n – 1}}} \right)\) \({\rm{d}}\) orbitals that are filled. An orbital of lower energy is filled first.

Atomic and Ionic Radii

Ions of the same charge in a given series have a regular decrease in radius with increasing atomic number because when a new electron enters into a d-orbital, the effective nuclear charge increases by one unit.

The final series shows a small increase in size due to electron-electron repulsion.

Atomic and ionic radii increase from the third to the fourth series, but the radii of the third \(\left( {{\rm{5d}}} \right)\) series elements are nearly the same as those of the corresponding member of the second series. This is because of lanthanoid contraction [inadequate \({\rm{4f}}\) shielding].

\({\rm{Zr}}\) and \({\rm{Hf}}\) are affected by lanthanide contraction. They have nearly identical radii.

Ionisation Energy

Because of their small size, transition elements have high ionisation energy. Their ionisation potentials are intermediate between those of the \({\rm{s}}\) and \({\rm{p}}\) block elements. As a result, they have less electropositive character than \({\rm{s}}\)-block elements. As a result, they do not form ionic compounds as quickly as alkali, and alkaline earth metals do. They are also capable of forming covalent compounds.

As we move from left to right, the ionisation potentials of \({\rm{d}}\)-block elements increase. The second ionisation energies of the first transition series rise in tandem with the increase in nuclear number. \({\rm{Cr}}\) and \({\rm{Cu,}}\) for example, have higher energies than their neighbours.

Oxidation States

Except for the first and last elements in the series, all of the transition elements exhibit different oxidation states. They indicate variable valency in their compounds. The tables below show some of the basic oxidation conditions of the elements in the first, second, and third transition series.

Melting and Boiling point

\({\rm{d}}\) -block elements have a high melting point and boiling point due to the strong metallic bond. The melting point of these elements reaches a maximum and then decreases as the atomic number increases.

Manganese and technetium have out-of-the-ordinary values in the trend. The highest melting point is that of tungsten \(\left( {{\rm{3422}}\,^\circ {\rm{C}}} \right).\)

Because of the absence of unpaired electrons and weak metallic bonding, Mercury is liquid at room temperature \(\left( {{\rm{M}}.{\rm{P}}.{\rm{ – – 38}}.{\rm{9}}\,^\circ {\rm{C}}} \right).\)

Metallic Nature

Because there are lesser electrons in the peripheral shell, all transition elements are metals. They demonstrate the properties of metals in nature, such as ductility and malleability, and shape alloys with a few different metals. They are also excellent conductors of electricity and heat. With the exception of Mercury, which is fluid and delicate like alkali metals, all transition elements are hard and fragile, unlike non-transition elements.

Density

Because of their small atomic size and strong metallic bonding, \({\rm{d}}\)-block elements have a high density. Among the transition series, the density trend will be the inverse of the atomic radii, i.e., density first increases then remain nearly constant and then decreases over the period.

Osmium has a slightly lower density \(\left( {{\rm{22}}.{\rm{57g}}{\mkern 1mu} {\rm{c}}{{\rm{m}}^{ – 3}}} \right)\) than iridium \(\left( {{\rm{22}}.{\rm{61}}{\mkern 1mu} {\rm{c}}{{\rm{m}}^{ – 3}}} \right)\) at room temperature. As a result, iridium has the highest density of any transition metal.

Coloured Ions

When white light is incident on a transition metal ion, the colour is caused by the presence of unpaired electrons in \({\rm{d}}\) -orbitals due to the \({\rm{d – d}}\) transitions of these unpaired electrons.

When white light strikes a transition metal ion, the unpaired electron in the lower energy \({\rm{d}}\)-orbital set absorbs certain radiations and is promoted to a higher energy \({\rm{d}}\)-orbital set. The complementary colour of the absorbed light is visible in the transmitted radiation that is devoid of the absorbed radiations.

Magnetic Properties

The number of unpaired electrons in a \({\rm{d}}\)-Block element determines its magnetic properties.
a. The presence of unpaired electrons in \({\rm{d}}\)-orbitals causes paramagnetic behaviour. The paramagnetic character increases with the number of unpaired electrons. These substances are pulled in by the magnetic field.
b. Diamagnetic substances- The absence of unpaired electrons results in the appearance of the diamagnetic character. These are repelled by a magnetic field and contain no unpaired electrons.
c. In ferromagnetism, a substance, such as Fe acquires a permanent magnetic character.

The magnetic moment is given by-
\({\rm{u = }}\sqrt {{\rm{n}}\left( {{\rm{n + 2}}} \right)} {\rm{\;BM}}\)

Where n is the number of unpaired electrons, and \({\rm{BM}}\) is the Bohr magneton (unit of the magnetic moment).

Formation of Complexes

Coordination compounds are those in which the central metal ion holds onto a small number of electron-rich neutral molecules or anions. \({\rm{d}}\)-orbitals are the building blocks of a large number of coordination compounds. This is primarily because-
i. Small atomic size and a large nuclear charge
ii. The presence of partially filled \({\rm{d}}\)-orbitals
iii. \({\rm{d}}\)-orbitals that are not occupied.

Catalytic Properties

The \({\rm{d}}\)-block element ions in their various oxidation states are widely used in industry as catalysts to facilitate faster and more efficient reactions. The Contact process is catalysed by vanadium in its \( + 5\) oxidation state. Haber’s process employs finely divided iron as a catalyst, and nickel is used as a catalyst in the hydrogenation process.

Applications of d-Block Elements

Transition elements find their uses in various places. Some of the applications are given below-
i. Iron and steel are used to make tools, utensils, vehicles, bridges, and a variety of other items.
ii. \({\rm{Ti}}{{\rm{O}}_{\rm{2}}}\) is used in the pigment industry, while \({\rm{Mn}}{{\rm{O}}_{\rm{2}}}\) is used in dry battery cells.
iii. \({\rm{Zn}}\) and \({\rm{Ni}}\) / \({\rm{Cd}}\) are used in the battery industry.
iv. Group \(11\) elements are known as coinage metals.
v. In the production of sulfuric acid, \({{\rm{V}}_{\rm{2}}}{{\rm{O}}_{\rm{5}}}\) catalyses the oxidation of \({\rm{S}}{{\rm{O}}_{\rm{2}}}.\)
vi. In the Haber process, iron catalysts are used to produce ammonia from \({{\rm{N}}_{\rm{2}}}{\rm{/}}{{\rm{H}}_{\rm{2}}}\) mixtures.
vii. Nickel catalysts enable fat hydrogenation.
viii. Nickel can be used to polymerize alkynes and other organic compounds such as benzene.
ix. The photographic industry relies on silver bromide’s unique light-sensitive properties.

Summary

In this article, we have studied the general properties of \({\rm{d}}\)- block elements which are also known as transition elements. We have studied the following-
i. The electronic configuration of \({\rm{d}}\)-block elements is \(\left( {{\rm{n – 1}}} \right){{\rm{d}}^{{\rm{1 – 10}}}}{\rm{n}}{{\rm{s}}^{{\rm{1 – 2}}}}{\rm{.}}\)
ii. \({\rm{d}}\)-block elements demonstrate the qualities of metals.
iii. They have high melting and boiling points.
iv. Their density first increases then gradually decreases from \({\rm{Cu}}\) to \({\rm{Zn}}{\rm{.}}\)
v. The ionic radii of these elements gradually decrease with an increase in the atomic number.
vi. The \({\rm{d}}\)-block elements exhibit various oxidation states.

FAQs on General Properties of d-Block Elements

Q.1. What exactly do you mean by the \({\rm{d – d}}\) transition?
Ans: The unpaired electrons in transition metals can be advanced from one energy level to another in similar \({\rm{d}}\)-orbitals. This is known as \({\rm{d – d}}\)-transition. This property indicates the colour of transition elements.

Q.2. What exactly are transition elements, and why are they named so?
Ans: \({\rm{d}}\) -block elements that have partially filled \({\rm{d}}\) -orbitals in their ground state or at least one of their oxidation states are called transition elements. They are so-called because their properties fall somewhere between those of s-block elements and those of \({\rm{p}}\) -block elements. They are more electropositive than \({\rm{p}}\) -block elements but less than \({\rm{s}}\) -block elements. They are all metals.

Q.3. What exactly are transition elements?
Ans: Transition elements have properties that are intermediate between \({\rm{s}}\)-block and \({\rm{p}}\)-block elements. They are more electropositive than \({\rm{p}}\)-block elements but less than \({\rm{s}}\)-block elements. They are all metals.

Q.4. What is the reactivity of transition elements?
Ans: Transition metals are located in the middle of the periodic table, between groups \(2\) and \(13.\) They are generally harder and thicker and less reactive than alkali metals. Transition metals such as iron, copper, silver, and gold are essential.

Q.5. What are the general properties of \({\rm{d}}\)-block elements?
Ans: The following are the general properties of transition elements:
i. They create stable complexes.
ii. These materials have high melting and boiling points.
iii. Have a high charge/radius ratio.
iv. Form compounds that are frequently paramagnetic.
v. They are hard and have a high density.
vi. Create compounds with high catalytic activity.
vii. Display varying oxidation states.

Q.6. What are the \({\rm{d}}\)-block elements? Write any four properties.
Ans: The\({\rm{d}}\)-block elements are located in the middle of the periodic table, between groups \(2\) and \(13.\) They are generally harder and thicker and less reactive than alkali metals. They have a general electronic configuration as \(\left( {{\rm{n – 1}}} \right){{\rm{d}}^{{\rm{1 – 10}}}}{\rm{n}}{{\rm{s}}^{{\rm{1 – 2}}}}{\rm{.}}\)
The four properties are as follows:
i. They have varying oxidation states.
ii. They produce coloured ions.
iii. They serve as a catalyst.
iv. They combine to form alloys.

Q.7. Which is the first element of the \({\rm{d}}\)-block?
Ans: The first element of the \({\rm{d}}\)-block is scandium which is denoted by ‘\({\rm{Sc}}\)’.

Learn about Alkali Metals here

We hope this detailed article on the general properties of \({\rm{d}}\)-block elements will be helpful in your preparation. If you have any doubts related to the article or, in general, about the \({\rm{d}}\)-block elements, please reach out to us through the comments section, and we will get back to you as soon as possible.