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The D and F Block Elements Class 12 Notes PDF - CBSE Chemistry Chapter 8

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CBSE Class 12 Chemistry Chapter 8 - d and f Block Elements Notes - Free PDF Download

The middle layer present in the periodic table is filled with the d block elements. The inner d orbits of group 3 to 13 are progressively filled. On the other side, the f block elements are found outside and at the bottom of the periodic table. In these elements, the 5f and 4f orbitals are progressively filled. The 3 series of transition elements are recognised by the filling of 3d, 4d, and 5d orbitals. They hold a high boiling and melting point. The metallic properties that are exhibited by the transition elements are given as follows:

  • Electrical conductivity

  • Thermal conductivity

  • Malleability

  • Metallic character

  • High tensile strength

  • Ductility

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The Class 12 d and f Block Notes Chemistry - Basic Subjective Questions

Section – A (1 Mark Questions)

1. Why copper is transition metal?

Ans. It is because Cu+2 has 3d9 configuration, incompletely filled d-orbitals, therefore, it is a transition metal.


2. Which contraction is more actinoid or Lanthanoid and how?

Ans. 5f orbitals have poor shielding effect than 4f orbitals, therefore, effective nuclear charge is more in actionids than lanthanide making actionid contraction greater than lanthanoid contraction.

3. Copper does not replace hydrogen from acids. Why?

Ans. Cu shows Eº positive value. Cu is less reactive than hydrogen so it won't be able to be replaced from acids.

4.  Among Cu2Cl2 and CuCl2, which is more stable and why?

Ans. CuCl2 is more stable than Cu2Cl2. The stability of Cu2+ (aq.) rather than Cu+(aq.) is due to the much more negative $\Delta _{hyd}H^{-}$ of Cu2+(aq) than Cu+(aq ).

5. Catalyst used in Haber’s process.

Ans. Finely divided iron is used as a catalyst in Haber's process.

6. Use of Nickel is used in which reaction?

Ans. Ni is used as a catalyst in catalytic hydrogenation reactions.

7. Alloy is ?

Ans. An alloy is a homogeneous mixture of two or more metals, e.g. Brass (Cu-Zn)

8. Transition metal of 3d series which exhibits the largest number of oxidation states and why?

Ans. Manganese: It has a maximum number of unpaired electron. It has 5 unpaired electrons.

9. Why is the radii of transition metals of 2nd series and 3rd series are very similar?

Ans. The second and third transition elements have almost similar atomic radii.It is due to lanthanide contraction.It arises due to poor shielding of d and f electrons.

10. Third ionization is low for which Lanthanoid?

Ans. Europium (Eu)

Section – B (2 Marks Questions)

11. Transition elements shows variable oxidation state .Why ?  How is the variability in oxidation states of d-block different from that of the p-block elements?

Ans. It is due to similar energy of (n – 1)d and ns orbitals, electrons from both can be lost. In p-block, lower oxidation state is more stable due to inert pair effect, whereas in d-block elements higher oxidation states are more stable. In d-block, oxidation states differ by one, whereas in p-block, it differs by two.

12. (i) Actinoids shows wide range of oxidation states . Why?

(ii) Lanthanides & actinides  are oloured. Explain?

Ans. (i) It is because 5f, 6d and 7s have comparable energy.

(ii) The colour of Lanthanoids and Actinoids is due to f-f transitions. When one or more unpaired electrons are present in the f orbital, light in the visible region is absorbed which results in f-f transition and colour.

13.Explain the following observations:

(i)  In  the first series of transition elements there is an increase in density of elements from titanium (Z = 22) to copper (Z = 29). 

(ii) Why transition metals act as good catalyst in chemical reaction.

Ans.(i) From titanium to copper the atomic size of elements decreases and mass increases as a result of which density increases.

(ii) The catalytic properties of the transition elements are due to the presence of unpaired electrons in their incomplete d-orbitals and variable oxidation states.

14.Complete the following chemical equations:

(i) MnO4-(aq) + S2O32– (aq) + H2O (l) →

(ii) Cr2O72– (aq) + Fe2+(aq) + H+(aq) →

Ans.(i)$8MnO_{4}^{-}(aq)+3S_{2}O_{3}^{-}(aq)+H_{2}O(l)\rightarrow 8MnO_{2}(s)+6SO_{4}^{2-}(aq)+2OH^{-}(aq)$

(ii) $Cr_{2}O_{7}^{2-}+6Fe^{2+}+14H^{+}\rightarrow 2Cr^{3+}+6Fe^{3+}+7H_{2}O$

15. Describe interstitial compounds? Why interstitial compounds well known for transition metals?

Ans. Interstitial compounds are those which are formed when small atoms like H, N or C are trapped inside the crystal lattices of metals. They are usually non-stoichiometric and are neither typically ionic or covalent.

Interstitial compounds are well known for transition compounds due to its closed crystalline structure with voids in them. The atomic size of transition metals are very large hence have large voids to occupy these small atoms.

16. Define lanthanoid contraction? What are its causes and consequences?

Ans. Lanthanoid contractions– The cumulative effect of the regular decrease in size or radii of Lanthanoid with increase in atomic number is called Lanthanoid contraction.

Its Causes:- The shape of f orbitals is diffused. They have poor shielding effect due to which the effective nuclear charge increases with increase in atomic number. This causes a decrease in atomic radii Its Consequence are : Due to Lanthanoid contraction: 

1. Radii of the members of the third transition series are similar to those of second transition series.

2. It becomes difficult to separate Lanthanides.

17. Put some light on the characteristics of  interstitial compounds

Ans. Some characteristics of interstitial compounds are

(i) They have high melting points.

(ii) They are very hard

(iii) They retain metallic lusture.

(iv) They are chemically inert.

18. What will be the product when the 

(i) Reaction of  lanthanide takes place with dil-acid

(ii) Reaction of lanthanide  takes place with water.

Ans. (i) When a Lanthanoid reacts with dil-acid, it liberate hydrogen gas.

Ln + dil.HCl → LnCl3 + H2

(ii) When a Lanthanoid reacts with water, it forms hydroxide.

Ln + H2O → Ln (OH)3 + H2

19. Explain:

(i) Why some compounds of transition metals shows paramagnetic behaviour.

(ii) Why enthalpies of atomisation is high for transition metals.

Ans. (i) Transition metals and many of their compounds show paramagnetic behaviour.

This is due to presence of one or more unpaired electrons in d subshell.

(ii) The enthalpies of atomisation of the transition metals are high.

This is due to high effective nuclear charge and large number of valence electrons. This results in formation of strong metallic bonds.

20. Describe the general trends in the following properties of first series 3d  transition elements: (i) Why +2 oxidation state is most stable.

Ans. (i) The elements of first transition series show decreasing tendency to form divalent cation as we move left to right in the series. This trend is due to general increase in the first and second ionization energy. The greater stability of Mn2+ is due to half filled d5 configuration and that of zinc is due to d10 configuration.

PDF Summary - Class 12 Chemistry The d-and f-Block Elements Notes (Chapter 8)

The notes of chapter 8 chemistry class 12 are great for the students who are looking to learn the periodic table in a simple manner. In other terms, you will learn that the periodic table is only one part of Chemistry. While it can scare students easily, this chapter will change that most definitely. Consequently, it also enables the students to learn about it in groups. So, the chapter will only focus on the d-block and f-block elements of the table. Therefore, the plus two chemistry d and f block elements notes make your study easier.

Sub-topics covered Under the d and f Block Elements

The sub-topics that are covered under the d block and f block elements are listed below:

  • Electronic configuration of the d-block elements - This chapter makes it easier to recollect the numerous configurations and properties of the elements that belong to the same group

  • Position in the Periodic Table - Here, students will learn about the periodic table position of an element and its nature and properties

  • Some Applications of d-block and f-block elements - It will explain the students about the numerous applications of d-block and f block elements

  • Some Important Compounds of Transition Elements - This complete section discusses the important compounds of transition elements, as well as their properties 

  • The Actinoids - Here, the students will learn about the new set of elements which are not-so-known through this unit, that are Actinoids

  • The Lanthanide - This section explains the detail information of hidden element of the lanthanide

  • General Properties of the Transition Elements (d-block) - It also gives a closer look at various properties of the transition elements

Position in the Periodic Table

The d block and f block elements in the groups ranging from 3 to 11 are also known respectively as the transition elements and inner transition elements. The 4f and 5f orbitals of f-block elements reside steadily in the later of two long periods. On this basis, they are differentiated in lanthanides and actinides. The d block elements, which are called transition elements, contain partially filled (n-1) d-orbitals. The periodic table position of an element is highly reflective of its nature and properties.

Topics of d and f Block Elements

Let us look at some of the topics that are covered in the revision notes of f and d block elements:

  • Definition of d and f block elements

  • Electronic Configuration

  • Metallic character

  • Ionic radii

  • Melting point

  • Oxidation state

  • Catalytic property

  • Complex formation

  • Compounds of transitional elements

  • Mercury Chlorides

Benefits of Class 12 d and f Block Notes

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Benefits of Early Revision

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Less Stress

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Key Points on d and f Block Elements

The following are the important points and concepts that are related to the chapter on d and f Block Elements: 

  • D Block Elements

  • General Properties of D-Block Elements

  • Important Alloys

  • F Block Elements

  • Lanthanide Contraction

Important Topics for the d and f block Elements Class 12 Notes PDF

Explore the essential topics covered in Class 12 d and f block Elements notes through the curated list of important topics. These notes delve into the fundamental concepts of d and f block Elements, providing comprehensive coverage of key areas essential for a thorough understanding of the subject. Whether you're reviewing for exams or seeking a deeper comprehension of d and f block Elements, this list of links serves as a valuable resource to aid in your the d and f block Elements Class 12 Notes PDF.

Other Related Links

The following is a list of links that take you to the important revision notes for Class 12 Chemistry chapter-wise revision notes by our expert teachers. 

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Important D and F Block Elements Related Links

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Important Class 12 Study Materials Links

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The CBSE d and f Block Elements Class 12 PDF Notes, available for free PDF download, serve as an invaluable resource for students studying transition and inner transition elements. These comprehensive notes cover essential topics such as electronic configurations, magnetic properties, and complex formation, providing a strong foundation for understanding the unique characteristics of these elements. With clear explanations and illustrative diagrams, these notes facilitate a deeper comprehension of the subject matter. Students can enhance their problem-solving skills and excel in examinations with the aid of these well-structured and easily accessible d and f Block Elements Class 12 PDF Notes. Ultimately, these resources contribute significantly to fostering a better grasp of D and F Block Elements in the Class 12 Chemistry curriculum.

FAQs on The D and F Block Elements Class 12 Notes PDF - CBSE Chemistry Chapter 8

1. Explain the Features of d-block Elements?

  • The general electronic configuration of the d-block elements is given by (n −1) d1-10 ns1-2, where (n −1) stands for the inner d orbitals

  • In the d-block, each horizontal row consists of 10 elements as d-subshell, and it can accommodate a maximum of 10 electrons

  • The d-block elements with the incompletely filled d-subshell are known as transition metals

2. Give the Characteristics of Actinoids and Lanthanoids?

  • Lanthanoids are silvery-white soft metals which tarnish readily when they are exposed to air

  • The hardness of the lanthanoids increases with an increase in the atomic number

  • The melting point and boiling point of actinoids are moderately high, but they are considerably lower to that of transition elements

3. Explain the Characteristics of f Block Elements?

  • In general, these elements have a higher melting point and boiling point

  • These are usually heavy metals

  • They are the elements that tend to form coloured ions

  • They also display a variety of oxidisation states

  • They can form complex compounds

4. What are the transition elements? Write 3 characteristics of the transition elements. 

Elements whose d-orbital is partially filled in the ground states or in any one of the oxidation states of the element are known as transition elements. Their characteristics are:

  • Showing variable states of oxidation.

  • Forming coloured ions.

  • Forming complex compounds.

5. What is lanthanoid contraction? 

The overall decrease in atomic and ionic radii with an increase in atomic number is known as lanthanoid contraction. The size of the ion decreases as the lanthanide series progresses from La+3 to Lu+3. The lanthanoid contraction refers to the drop in size in the series. This occurrence occurs as a result of a 4f electron being imperfectly shielded by a separate election from the same subshell.

6. Mention the main consequences of lanthanoid contraction.

The similarity of properties because of the lanthanoid contraction, size of elements following (Hf – Hg) become very similar to the size of the previous row elements (Zr – Cd) and therefore they become difficult to make out. Because of small changes in the atomic radii, the properties of lanthanoids are also almost similar making separation very difficult.

Basicity difference is because of the lanthanoid contraction, where size reduces from La+3 to Lu+3. Therefore the covalent character improves. Thus, the basic characteristic of the hydroxides also reduces i.e. the reason La(OH)3 has the highest basicity while Lu(OH)3 has the least.

7. What is meant by ‘’disproportionation’? 

Lanthanide contraction is the general reduction in atomic and ionic radii with increasing atomic number. When the lanthanide series proceeds from La+3 to Lu+3, the ion's size decreases. The lanthanoid contraction refers to the series' decrease in size. This happens when a 4f electron is poorly protected by a distinct election from the same subshell.

8. Why do transition elements show variable oxidation states?

Since there is relatively little energy difference between the (n-1) d-orbital and ns-orbital, transition elements have varying oxidation states. Due to the little difference in energy between the orbitals, both energy levels can be utilized to establish a bond. As a result, transition elements can have a range of oxidation states.

9. What is the d and f block elements class 12 notes?

D and f-block Class 12 NCERT notes provide detailed information about the elements belonging to the d-block and f-block of the periodic table. These notes cover their electronic configurations, properties, and trends in chemical behavior, as outlined in the NCERT textbook for Class 12.

10. What are the basic concepts of D and f-block elements?

The basic concepts of D and f-block elements include understanding their electronic configurations, oxidation states, magnetic properties, and chemical reactivity. Students learn about the transition metals' ability to form colored compounds, act as catalysts, and exhibit variable oxidation states, while the f-block elements often display lanthanide contraction and actinide series characteristics.