d-Block Elements(Transition Elements)-Position of Elements in the Periodic Table, Properties, FAQs

General Properties of Transition Elements

The electron configuration corresponds to (n-1)d5 ns1 or (n-1)d10 ns1. This is due to the stability offered by electron orbitals that are half-full or totally filled. Zinc, cadmium, and mercury are not considered transition elements because their electrical configurations differ from those of other transition metals. The properties of the remaining d-block elements, on the other hand, are quite similar, and this likeness may be seen down each row of the periodic table.

The properties of the second and third-row elements gradually change as we move from left to right along the periodic table. The outer shells of these elements have poor shielding properties, which raises the effective nuclear charge as more protons are added to the nucleus. The characteristics of the transition elements are listed below.

  • When these elements mix, they form colorful compounds and ions. The electron d-d transition explains its color.
  • The energy difference between these elements’ possible oxidation states is modest. As a result, transition elements have a wide range of oxidation states.
  • These elements produce a huge number of paramagnetic compounds due to the unpaired electrons in the d orbital.
  • A vast variety of ligands can bind to these elements. As a result, transition elements produce a diverse array of stable complexes.
  • The charge-to-radius ratio of these elements is very high.
  • Transition metals are hard and have relatively high densities when compared to other elements.
  • Because delocalized d electrons engage in metallic bonding, these elements have high boiling and melting temperatures.
  • The transition elements are also good conductors of electricity due to the metallic bonding of the delocalized d electrons.

Position in Periodic Table: The d and f – block Elements

The study of which elements are in a specific group position in the periodic table is important for comprehending such elements as a whole. There is a reason why different elements in the periodic table are classified. The d and f block components have certain features that qualify them for this category.

The d-block elements are made up of elements created by electrons filling shells 3d, 4d, and 5d. They are also known as transition elements since their periodic table position is between the s-block and p-block elements. Their properties are transitional between the extremely reactive metallic elements of the s-block, which often form ionic compounds, and the predominantly covalent elements of the p-block.

D-block elements or transition elements are those elements or ions that have partially filled d sub-shell or those elements in which the differentiating electrons occupy (n-1) d sub-shell. They have named transition elements because their attributes reveal a transition from the left side (s-block) elements to the light side (p- block elements). There are four d-series, each beginning with (n-1)d1 ns2 and ranging from group 3 to group 12. (or group IIIB to II B).

In the d-block, electrons are added to the penultimate shell, increasing its size from 8 to 18. Typically, transition elements have an unfinished d level. Group 12 (zinc) has a d10 configuration, and because the d shell is complete, compounds of these elements are unusual and differ from the others. The elements are divided into three complete rows of ten elements each, as well as an incomplete fourth row. The f-block parts are used to discuss the position of the unfinished fourth series. These elements include precious metals such as silver, gold, and platinum, as well as industrially vital elements such as iron, copper, and nickel.

Transition or d-block elements lies in the middle of the periodic table, from Group 3 to 12, are referred to as d-block elements. The name d-block comes from the fact that the final electron enters the d-orbital of the penultimate shell. These are frequently referred to as transition elements because their properties fall in between highly reactive metallic s-block elements and nonmetallic p-block elements. The d block contains four series that correspond to the filling of 3d, 4d, 5d, or 6d orbitals.

Position of transition metals in the periodic table

  • Inner transition elements are another term for ‘f’ – block elements. In these elements, the last electron normally enters the orbital’s penultimate, i.e. (n – 2) f. The distinguishing electron in transition elements can enter either 4f or 5f orbitals, allowing them to be further classified as lanthanides or actinides.
  • The differentiating electron in lanthanides reaches the 4f orbital. These range from cerium to lutetium. Lanthanides are named for the elements that come directly the following lanthanum. The differentiating electron in actinides enters the 5f orbitals. Typically, they are thorium to lawrencium.
  • In the periodic table, these elements appear shortly the following actinium. (n–2) f1–14(n–1) d0–1ns2 is the general electronic configuration of f – block elements. Lanthanides have an electronic configuration of [Xe]4f1–145d0–16s2, whilst Actinides have an electronic configuration of [Rn]5f1–146d0–17s2.

Sample Questions (FAQs)

Question 1: What are the transition metals’ metallic properties?

Answer:

Malleability, ductility, high tensile strength, and metallic lustre are all characteristics of transition metals. They are good heat and electrical conductors and have a tendency to crystallise. Trends in the metallic properties of transition elements, on the other hand, are visible. Elements such as chromium and molybdenum are among the hardest transition metals because they contain a large amount of unpaired electrons.

Question 2: Why are all the transition elements metals?

Answer:

All transition elements are metals because their outermost shells contain only two electrons. Because of the strong metallic linkages, they are also malleable, durable, and ductile.

Question 3: How do the d-block elements differ from f-block elements?

Answer:

The last electron in the d-block enters the d-orbital of the penultimate shell. The electron enters the f-orbital of the anti-penultimate shell in the f-block elements. The oxidation state of d-block elements varies, whereas the oxidation state of most f-block elements is +3. Almost all d-blocks are stable, whereas a greater proportion of f-blocks are radioactive.

Question 4: What are the catalytic properties of transition elements?

Answer: 

Because of the presence of unoccupied d-orbitals, the tendency to exhibit fluctuating oxidation states, the ability to generate reaction intermediates with reactants, and the presence of defects in their crystal lattices, transition elements exhibit catalytic capabilities.

Question 5: Why do d – Block Elements have high Melting and Boiling Points?

Answer:

In addition to metallic bonding by s-electrons, unpaired electrons and vacant or partially full d-orbitals produce covalent bonds. D-block elements have higher melting and boiling temperatures than s and p block elements due to their strong bonding. This trend continues until the d5 configuration, at which point it begins to decline as more electrons are coupled in the d-orbital.

Er. Neeraj K.Anand is a freelance mentor and writer who specializes in Engineering & Science subjects. Neeraj Anand received a B.Tech degree in Electronics and Communication Engineering from N.I.T Warangal & M.Tech Post Graduation from IETE, New Delhi. He has over 30 years of teaching experience and serves as the Head of Department of ANAND CLASSES. He concentrated all his energy and experiences in academics and subsequently grew up as one of the best mentors in the country for students aspiring for success in competitive examinations. In parallel, he started a Technical Publication "ANAND TECHNICAL PUBLISHERS" in 2002 and Educational Newspaper "NATIONAL EDUCATION NEWS" in 2014 at Jalandhar. Now he is a Director of leading publication "ANAND TECHNICAL PUBLISHERS", "ANAND CLASSES" and "NATIONAL EDUCATION NEWS". He has published more than hundred books in the field of Physics, Mathematics, Computers and Information Technology. Besides this he has written many books to help students prepare for IIT-JEE and AIPMT entrance exams. He is an executive member of the IEEE (Institute of Electrical & Electronics Engineers. USA) and honorary member of many Indian scientific societies such as Institution of Electronics & Telecommunication Engineers, Aeronautical Society of India, Bioinformatics Institute of India, Institution of Engineers. He has got award from American Biographical Institute Board of International Research in the year 2005.

CBSE Class 12 Chemistry Syllabus Download PDF

Below is the CBSE Class 12 Syllabus along with the marking scheme and time duration of the Chemistry exam.

S.NoTitleNo. of PeriodsMarks
1Solutions107
2Electrochemistry129
3Chemical Kinetics107
4d -and f -Block Elements127
5Coordination Compounds127
6Haloalkanes and Haloarenes106
7Alcohols, Phenols and Ethers106
8Aldehydes, Ketones and Carboxylic Acids108
9Amines106
10Biomolecules127
Total70

CBSE Class 12 Chemistry Practical Syllabus along with Marking Scheme

The following is a breakdown of the marks for practical, project work, class records, and viva. The total number of marks for all parts is 15. The marks for both terms are provided in the table below.

Evaluation Scheme for ExaminationMarks
Volumetric Analysis08
Salt Analysis08
Content-Based Experiment06
Project Work and Viva04
Class record and Viva04
Total30

CBSE Class 12 Chemistry Syllabus (Chapter-wise)

Unit -1: Solutions

  • Raoult's law.
  • Colligative properties - relative lowering of vapour pressure, elevation of boiling point, depression of freezing point, osmotic pressure, determination of molecular masses using colligative properties, abnormal molecular mass.
  • Solutions, Types of solutions, expression of concentration of solutions of solids in liquids, solubility of gases in liquids, solid solutions.
  • Van't Hoff factor.

Unit -2: Electrochemistry

  • Redox reactions, EMF of a cell, standard electrode potential
  • Nernst equation and its application to chemical cells
  • Relation between Gibbs energy change and EMF of a cell
  • Kohlrausch's Law
  • Electrolysis and law of electrolysis (elementary idea)
  • Dry cell-electrolytic cells and Galvanic cells
  • Conductance in electrolytic solutions, specific and molar conductivity, variations of conductivity with concentration.
  • Lead accumulator
  • Fuel cells

Unit -3: Chemical Kinetics

  • Rate of a reaction (Average and instantaneous)
  • Rate law and specific rate constant
  • Integrated rate equations and half-life (only for zerfirst-order order reactions)
  • Concept of collision theory (elementary idea, no mathematical treatment)
  • Factors affecting rate of reaction: concentration, temperature, catalyst;
  • Order and molecularity of a reaction
  • Activation energy
  • Arrhenius equation

Unit -4: d and f Block Elements  

  • Lanthanoids- Electronic configuration, oxidation states, chemical reactivity and lanthanoid contraction and its consequences.
  • Actinoids- Electronic configuration, oxidation states and comparison with lanthanoids.
  • General introduction, electronic configuration, occurrence and characteristics of transition metals, general trends in properties of the first-row transition metals – metallic character, ionization enthalpy, oxidation states, ionic radii, color, catalytic property, magnetic properties, interstitial compounds, alloy formation, preparation and properties of K2Cr2O7 and KMnO4.

Unit -5: Coordination Compounds  

  • Coordination compounds - Introduction, ligands, coordination number, color, magnetic properties and shapes
  • The importance of coordination compounds (in qualitative analysis, extraction of metals and biological system).
  • IUPAC nomenclature of mononuclear coordination compounds.
  • Bonding
  • Werner's theory, VBT, and CFT; structure and stereoisomerism

Unit -6: Haloalkanes and Haloarenes  

  • Haloarenes: Nature of C–X bond, substitution reactions (Directive influence of halogen in monosubstituted compounds only). Uses and environmental effects of - dichloromethane, trichloro methane, tetrachloromethane, iodoform, freons, DDT.
  • Haloalkanes: Nomenclature, nature of C–X bond, physical and chemical properties, optical rotation mechanism of substitution reactions.

Unit -7: Alcohols, Phenols and Ethers   

  • Phenols: Nomenclature, methods of preparation, physical and chemical properties, acidic nature of phenol, electrophilic substitution reactions, uses of phenols.
  • Ethers: Nomenclature, methods of preparation, physical and chemical properties, uses.
  • Alcohols: Nomenclature, methods of preparation, physical and chemical properties (of primary alcohols only), identification of primary, secondary and tertiary alcohols, mechanism of dehydration, and uses with special reference to methanol and ethanol.

Unit -8: Aldehydes, Ketones and Carboxylic Acids   

  • Carboxylic Acids: Nomenclature, acidic nature, methods of preparation, physical and chemical properties; uses.
  • Aldehydes and Ketones: Nomenclature, nature of carbonyl group, methods of preparation, physical and chemical properties, mechanism of nucleophilic addition, the reactivity of alpha hydrogen in aldehydes, uses.

Unit -9: Amines    

  • Diazonium salts: Preparation, chemical reactions and importance in synthetic organic chemistry.
  • Amines: Nomenclature, classification, structure, methods of preparation, physical and chemical properties, uses, and identification of primary, secondary and tertiary amines.

Unit -10: Biomolecules     

  • Proteins -Elementary idea of - amino acids, peptide bond, polypeptides, proteins, structure of proteins - primary, secondary, tertiary structure and quaternary structures (qualitative idea only), denaturation of proteins; enzymes. Hormones - Elementary idea excluding structure.
  • Vitamins - Classification and functions.
  • Carbohydrates - Classification (aldoses and ketoses), monosaccharides (glucose and fructose), D-L configuration oligosaccharides (sucrose, lactose, maltose), polysaccharides (starch, cellulose, glycogen); Importance of carbohydrates.
  • Nucleic Acids: DNA and RNA.

The syllabus is divided into three parts: Part A, Part B, and Part C. Part A consist of Basic Concepts of Chemistry, which covers topics such as atomic structure, chemical bonding, states of matter, and thermochemistry. Part B consists of Topics in Physical Chemistry, which includes topics such as chemical kinetics, equilibrium, and electrochemistry. Part C consists of Topics in Organic Chemistry, which covers topics such as alkanes, alkenes, alkynes, and aromatic compounds.

Basic Concepts of Chemistry:

  • Atomic structure: This section covers the fundamental concepts of atomic structure, including the electronic configuration of atoms, the Bohr model of the atom, and the wave nature of matter.
  • Chemical bonding: This section covers the different types of chemical bonds, including ionic, covalent, and metallic bonds, as well as the concept of hybridization.
  • States of the matter: This section covers the three states of matter - solid, liquid, and gas - and the factors that influence their properties.
  • Thermochemistry: This section covers the principles of thermochemistry, including the laws of thermodynamics and the concept of enthalpy.

Chapters in Physical Chemistry:

  • Chemical kinetics: This section covers the study of the rate of chemical reactions and the factors that influence it, including the concentration of reactants, temperature, and the presence of catalysts.
  • Equilibrium: This section covers the principles of chemical equilibrium, including the concept of Le Chatelier's principle and the equilibrium constant.
  • Electrochemistry: This section covers the principles of electrochemistry, including the concept of half-cell reactions, galvanic cells, and electrolysis.

Chapters in Organic Chemistry:

  • Alkanes: This section covers the properties and reactions of alkanes, including their structure, isomerism, and combustion.
  • Alkenes: This section covers the properties and reactions of alkenes, including their structure, isomerism, and addition reactions.
  • Alkynes: This section covers the properties and reactions of alkynes, including their structure, isomerism, and addition reactions.
  • Aromatic compounds: This section covers the properties and reactions of aromatic compounds, including their structure, isomerism, and electrophilic substitution reactions.

In addition to the topics covered in the syllabus, the CBSE Class 12 Chemistry exam also tests students on their analytical and problem-solving skills, as well as their ability to apply the concepts learned in the classroom to real-world situations.

Students can also check out the Tips for the Class 12 Chemistry Exam. They can easily access the Class 12 study material in one place by visiting the CBSE Class 12 page at ANAND CLASSES (A School Of Competitions). Moreover, to get interactive lessons and study videos, download the ANAND CLASSES (A School Of Competitions) App.

Frequently Asked Questions on CBSE Class 12 Chemistry Syllabus

Q1

How many chapters are there in the CBSE Class 12 Chemistry as per the syllabus?

There are 10 chapters in the CBSE Class 12 Chemistry as per Syllabus. Students can learn all these chapters efficiently using the study materials provided at ANAND CLASSES (A School Of Competitions).

Q2

What is the marking scheme for CBSE Class 12 Chemistry practical exam according to the syllabus?

The marking scheme for CBSE Class 12 Chemistry practical exam, according to the syllabus, is 8 marks for volumetric analysis, 8 marks for salt analysis, 6 marks for the content-based experiment, 4 marks for the project and viva and 4 marks for class record and viva.

Q3

Which is the scoring chapter in Chemistry as per CBSE Class 12 syllabus?

The chapter Electrochemistry in Chemistry is the scoring chapter as per CBSE Class 12 syllabus.