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Transition metals-Definition, Electronic configuration, General properties, Applications, Practice Problems, FAQ

Have you ever visited any historical museum?

What did you see there? In museums, we preserve old things related to history so that our coming generation must be aware of our wonderful history. You must have seen old dull coins, did you ever think what are the materials used in those coins. You must have seen the iron pillar in Mehrauli New Delhi. This is resistance to corrosion. You will find all these things very interesting. In chemistry, we have a class of metals known as transition metals, iron, copper, silver and gold are among the transition elements that have played important roles in the development of human civilisation. Let’s study the properties and behaviour of transition metals in detail.

Table of content:

  • What are transition metals?
  • Position in the periodic table
  • Electronic configuration
  • General Properties of Transition metals
  • Applications of transition metals
  • Practice Problems
  • Frequently asked questions-FAQ

What are Transition metals?

Transition metals are described as elements with partially full d-orbitals. An element with an incompletely filled d orbital capable of forming stable cations are known as transition element.
For example,

Position in Periodic table

Transition elements are the d-block elements in groups 3–11. The first transition series (elements Sc through Cu), the second transition series (elements Y through Ag), and the third transition series (elements Y through Ag) split the d-block elements (the element La and the elements Hf through Au). Ac is the first element in the fourth transition series, which also includes the elements Rf through Rg.

Group 12 metals zinc, cadmium, and mercury exhibit full d10 structure in both their ground and common oxidation states and are thus not considered transition metals.

Electronic configuration:

In general, these components' electrical configuration is (n-1)d1-10ns1-2.(n-1) denotes the inner d orbitals, which can contain one to ten electrons, and the outermost ns orbitals, which can have one or two electrons. Due to the small energy difference between (n-1)d and ns orbitals, this generalisation includes multiple exceptions. Furthermore, half-filled and fully-filled sets of orbitals are more stable. The generic formula (n-1)d10ns2 represents the electronic configurations of Zn ,Cd, and Hg. Both in the ground state and in their usual oxidation states, these elements' orbitals are totally filled. As a result, they have not considered transition elements.

General Properties of Transition Metals:

Because their electrical structures differ from other transition metals, the elements zinc, cadmium, and mercury are not considered transition elements. The rest of the d-block elements, on the other hand, have properties that are quite comparable, and this resemblance can be seen down each row of the periodic table. The transition element's characteristics are mentioned below.

  • Coloured compounds and ions are formed by these elements. The d-d electron transfer is responsible for its colour impart
  • The energy gap between these elements’ potential oxidation states is relatively small. As a result, the transition elements have a variety of oxidation states.
  • Because of the unpaired electrons in the d orbital, these elements generate a lot of paramagnetic compounds.
  • A wide range of ligands can interact with these components. As a result, transition elements can create a wide range of stable complexes.
  • These elements have a high charge-to-radius ratio.
  • When compared to other elements, transition metals are hard and have comparatively high densities.
  • Due to the inclusion of delocalized d electrons in metallic bonding, these elements have high boiling and melting temperatures.
  • The transition elements are good conductors of electricity because of the metallic bonding of the delocalized d electrons.
  • Most transition metal ions and complexes are paramagnetic, or attracted to the magnetic field, due to the existence of unpaired electrons in the (n-1) d-orbitals.
  • Transition metals form Interstitial compounds.

Atomic Radius:

Across a period: Due to increased nuclear charge, the atomic radii of representative (A group) elements decrease dramatically as we read across a period of elements. In the transition series, however, the decrease in atomic radii is not constant because electrons are added to an inner d subshell, which effectively shields the outer electrons, and thus the outer s electrons are not pulled closer, resulting in a very small decrease or relatively constant size as nuclear charge shielding increases.

Across a group: As you progress along with the group, you'll see an increase in the atomic and ionic radii of the elements. The presence of a greater number of subshells can explain the rise in radius. 

Ionization enthalpy:

The ionisation enthalpy increases along each sequence of transition elements from left to right due to an increase in nuclear charge associated with the filling of the inner d orbitals. However, there are numerous minor differences.
Though of minor chemical consequence, the uneven trend in the first ionisation enthalpy of 3d metals can be explained by noting how the removal of one electron changes the relative energies of 4s and 3d orbitals. As a result, the unipositive ions have dnconfigurations and no 4s electrons. As the number of electrons grow and the transference of s electrons into d orbitals occurs, there is a reorganisation energy associated with ionisation, as well as some gains in exchange energy. As the effective nuclear charge grows, the values are projected to rise. The number for Cr is lower because there is no change in the d configuration, while the value for Zn is larger because it represents ionisation from the 4s level.

Oxidation state

One of the distinguishing characteristics of a transition element is the wide range of oxidation states that it can exhibit in its compounds.

Transition Metal Oxidation States in the First Row (the most common ones are in bold types)

Sc

Ti

V

Cr

Mn

Fe

Co

Ni

Cu

Zn

+3




 

+2
+3
+4


 

+2
+3
+4
+5

 

+2
+3
+4
+5
+6
 

+2
+3
+4
+5
+6
+7

+2
+3

+4

+6
 

+2
+3

+4


 

+2
+3
+4


 

+1
+2



 

+2




 

Transition metals oxidation states in the second row (the most common ones in bold types)

Y

Zr

Nb

Mo

Tc

Ru

Rh

Pd

Ag

Cd

+3




 

+2
+3
+4


 


+3

+5


 

+1
+3
+4
+5
+6
 



+4

+6
+7

+2
+3

+4

+6
 

+2
+3

+4


 

+2

+4



 

+1
+2



 

+2




 

Transition metals oxidation states in the third row (the most common ones in bold types)

La

Hf

Ta

W

Re

Os

Ir

Pt

Au

Hg

+3




 


 

+4


 




+5
 

+1

+4
+5
+6
 


+3
+4


+6
+7



+4

+6
 


+3
+4



 

+2

+4



 

+1
+3


+5

 

+1
+2




 

 Application of Transition elements: 

  • Catalytic characteristics of some transition metals are highly beneficial in the industrial synthesis of various compounds.
  • Because transition metal ions are able to absorb visible light and migrate to higher energy orbitals, their compounds have vibrant colours.
  • Iron is a transition metal that is widely utilised in construction and manufacturing.
  • Titanium is utilised in aeroplane construction, artificial hip replacements, and nuclear power plant pipework.
  • Stainless steel is produced with nickel.
  • Electrical wiring is made of copper.

Related videos:

Practice problems:

Q1.Which is the lightest transition metal?
A) Co
B) Ni
C) Sc
D) Fe

Answer: C

Solution: The lightest transition element is Scandium (Sc). It is the first element of the 3d transition series. Sc has the lowest density among the transition elements.

Q2.Transition metals generally form coloured complexes. This is because of _____
A) Low threshold frequency.
B) They absorb electromagnetic radiation.
C) d-d transition of electrons..
D) None of the above.

Answer: C

Solution: Transition metals generally form coloured complexes. This is related to the absorption of visible light radiation in order to excite the d-electrons from one position to another in d-orbitals. Hence,
d-d transition is the major reason for the coloured complexes.

Q3.Why do transition elements have greater atomisation enthalpies?

Solution: They have stronger interatomic interaction and thus stronger bonding between atoms due to the huge amount of unpaired electrons in their atoms, resulting in higher enthalpies of atomisation.

Q4. Cr2+ and Mn3+ have d4 configuration, Cr2+ and Mn3+ acts as __________
A. Oxidising, Reducing agents respectively
B. Reducing, Oxidising agents respectively
C. Reducing agents
D. Oxidising agents

Answer: B

Solution: When Cr2+ is oxidised to Cr3+, its conformation changes from d4 to d3, making it a reducing agent. The d3 arrangement has a fairly steady half-filled t2g level. The reduction of Mn3+ to Mn2+, on the other hand, occurs in the half-filled (d5) structure, which is more stable, and so Mn3+ serves as an oxidising agent.

Frequently asked questions-FAQ

Question 1. Why do we need transition elements?
Solution: Transition elements are crucial to life and evolution. Without iron, oxygen would not reach the brain, and life would be impossible. Without the Stone Age, the bronze, iron, and steel ages would never have occurred. Transition metals have become increasingly important as our population and economy have grown.

Question 2. Why transition elements have been given the name of ‘transition’?
Solution: Because they transition between s-block and p-block elements, the d-block elements are called transition elements. Their properties are intermediate between the highly reactive metallic elements of the s-block, which are ionic in nature, and the covalent elements of the p-block.

Question 3. Who discover these transition elements?
Solution: Transition elements are discovered by English chemist Charles Rugeley Bury.

Question 4. Are transition metals flammable?
Solution: Transition metals are rarely combustible,i.e they are least flammable. Manganese is the exception.

Related topics

Iron

Potassium Permanganate

lanthanide contraction

Water

Hydrogen

Important compounds of Copper

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