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NCERT Solutions for Class 12 Chemistry Chapter 8 – The d and f Block Elements

NCERT Solutions for Class 12 Chemistry Chapter 8 – The d– and f– Block elements are carefully crafted by an expert team of Chemistry teachers. In this chapter, you will learn the positions and electronic configurations of the d– and f-block elements (transition and inner transition elements, respectively) in the periodic table. Here you will also understand their general characteristics, their general horizontal and group trends and relative stability of several oxidation states connected to values of their electrode potential. This chapter further describes the preparation, properties, structures and uses of some important compounds such as K2Cr2O7 and KMnO4. This chapter further presents a comparative account of the lanthanoids and actinoids.

There are 38 questions asked at the end of the chapter covering the different topics of NCERT Solutions for Class 12 Chemistry Chapter 8. These questions are related to the concepts of electronic configurations of transition elements and their ions, their characteristic properties, their compounds. Several questions are also based on the magnetic properties, colour of ions and chemical properties of transition and inner transition elements.

The solutions of Class 12 Chemistry Chapter 8 – The d– and f– Block elements give you an ample amount of practice and understanding of the chapter. This will also help you in your revisions during class 12th board exams. They also help you with your preparation for other competitive exams so that you can achieve success.

NCERT Class 12 Chemistry Chapter 8: Important Topics

NCERT Solutions for Class 12 Chemistry Chapter 8 – The d– and f– Block elements cover all the concepts given in the chapter. The outline of the concepts covered in this chapter has been given below.

I. The Transition Elements (d-Block)

  • Electronic Configurations of the d- Block Elements

This part of the CBSE NCERT Class 12 Chemistry Chapter 8 tells you that the d-block occupies the mid-portion of the periodic table and consists of Groups 3-12. The general electronic configuration of these elements is (n-1)d1-10ns1-2. The inner d orbitals of these elements are progressively filled. You further come to know that the transition elements show more similarity in their properties horizontally compared to the main group elements.

  • General Properties of the Transition Elements

This part of the chapter tells you that there are three rows of transition elements as per filling of 3d, 4d and 5d orbitals and all of them exhibit characteristic metallic properties such as ductility, high tensile strength, malleability, thermal and electrical conduction properties. They show high melting and boiling points which is due to the strong interatomic bonding displayed by (n –1) d electrons.

Most of these properties rise to a maximum at d5 configuration, that is middle of a row indicating one unpaired electron per d orbital provides a strong interaction between atoms.

  • Ionisation enthalpies and oxidation states

Here you will learn that there is an increase in ionisation enthalpies along with the addition of electrons one at a time in inner d orbitals from left to right but the increase is not as sharp as in the main group elements with increasing atomic number. These elements show variable oxidation states and certain discrete features due to involvement of (n–1) d electrons like they show catalytic properties, paramagnetic nature and the tendency for the formation of coloured ions, complexes and interstitial compounds.

Chemical reactivity and Eθ values

This part of the NCERT CBSE Class 12 Chemistry Chapter 8 tells you that transition metals usually vary in their chemical reactivity, some are electropositive to dissolve in mineral acids and some are noble. The transition metals show reactions with non-metals like halogens, sulphur, nitrogen and oxygen to give binary compounds.

  • Some Important Compounds of Transition Metals

This portion of NCERT Class 12 Chemistry Chapter 8 teaches you that the oxides of first series transition metals are usually formed when these metals react with oxygen at high temperatures. These oxides react with acids and bases to form oxo-metallic salts. The common examples are oxidising agents, K2Cr2O7 (prepared from the chromite ore) and KMnO4(prepared by using pyrolusite ore or MnO2.

II. The Inner Transition Elements (f-Block)

This part of the CBSE NCERT Class 12 Chemistry Book teaches you about the inner transition elements, lanthanoids and actinoids series of f-block. The f-block is kept at the bottom of the periodic table, and in the elements of this block, 4f and 5f orbitals are gradually filled. 

It further tells you that there is a gradual decrease, known as lanthanoid contraction, in the atomic and ionic sizes of these metals with a sequential filling of the inner 4f orbitals across the series. This is responsible for the unusual chemistry of the elements following them. 

This portion further tells you that lanthanoids, along with Lanthanum, are soft and white metals and react easily with water. The dominant oxidation state shown by these elements is +3, apart from +2 and +4 displayed occasionally by some elements.

This part of the chapter also talks about the complex chemistry of actinoids as they have the ability to exist in different oxidation states. Furthermore, studying actinoid elements is a hectic job as they are radioactive. 

This chapter tells you in detail about some of the uses of transition and inner transition elements, and their compounds, prominent among them are varieties of steels, catalysts, organic synthetic complexes.

CBSE NCERT Class 12 Chemistry Chapter 8 Exercise

Our NCERT Solutions for Class 12 Chemistry Chapter 8 – The d– and f– Block elements consists of 38 questions covering the important concepts learnt. The components of the exercise have been listed below. 

  • Question 1 asks you to write the electronic configuration of given ions.
  • Questions 2, 3, 21, 25 are reasoning questions.
  • Questions 4, 5, 23 are explanatory questions on electronic configurations of transition metals.
  • Questions 6 to 10 are direct questions on transition metals.
  • Question 11 is explanatory question properties shown by transition metals.
  • Questions 12 to 14 are direct questions based on compounds formed by transition metals.
  • Questions 15 and 16 are based on actions of potassium dichromate and potassium permanganate.
  • Question 17 is based on electrode potentials of transition metal ions.
  • Questions 18 and 24 are based on the availability of unpaired electrons in d orbitals.
  • Questions 19 and 20 are comparative questions.
  • Question 22 is based on a disproportionation reaction.
  • Question 26 is based on the preparation method of potassium dichromate and potassium permanganate.
  • Question 27 is a direct question about alloys.
  • Questions 28 to 30 are direct questions based on inner transition elements.
  • Questions 31 to 38 are based on various characteristics of lanthanoids and actinoids.

This chapter of CBSE NCERT Class 12 Chapter 8 also contains 10 intext questions from the main concepts taught in this chapter. All of these questions have been answered systematically in our solutions.

Benefits of NCERT Solutions for Class 12th Chemistry Chapter 8 – The d– and f– Block elements

Some of the key benefits of learning and revising from NCERT Solutions for Class 12 Chemistry Chapter 8 – The d– and f– Block elements are listed below.

  • These solutions take care of all your board exam preparation based requirements and provide the best content to study effectively and efficiently.
  • They help you in your quality revisions during class 12th board exams and also help you in excelling other competitive exams.
  • They cover all the topics and subtopics of this chapter and give meticulous and detailed answers to all the questions asked in the chapter with relevant examples.
  • They are perfect for comprehensive learning and problem-solving.
  • The solutions are drafted in a stepwise manner to keep your concepts clear and help you build a solid conceptual foundation.
  • They are a hundred percent accurate, easy to understand and precise.