Class 12 Chemistry Chapter 4: d and f Block Elements Notes for NEET & JEE (PDF + MCQs)
Class 12 Chemistry Chapter 4: The d- and f-Block Elements | Complete Notes for NEET & JEE
Introduction
The d- and f-block elements constitute an important part of the periodic table and are commonly known as transition and inner-transition elements. These elements exhibit unique physical and chemical properties such as variable oxidation states, colored ions, magnetic behavior, catalytic activity, and complex formation.
This chapter is highly important for NEET, JEE Main, JEE Advanced, and Board Examinations. Many direct and conceptual questions are asked from this unit every year.
Why is This Chapter Important for NEET & JEE?
✅ High-weightage Inorganic Chemistry chapter
✅ Frequently asked in NEET and JEE
✅ Direct NCERT-based questions
✅ Important for Board Examinations
✅ Easy scoring chapter with proper revision
✅ Foundation for Coordination Compounds
Download Study Material
📘 Complete d- and f-Block Elements Notes PDF
Position in the Periodic Table
d-Block Elements
The elements in which the last electron enters the d-subshell of the penultimate shell are called d-block elements.
These elements are located between the s-block and p-block elements.
Groups Included
Groups 3 to 12
Example Elements
Scandium (Sc)
Titanium (Ti)
Vanadium (V)
Chromium (Cr)
Manganese (Mn)
Iron (Fe)
Cobalt (Co)
Nickel (Ni)
Copper (Cu)
Zinc (Zn)
Transition Elements
Transition elements are those elements that have partially filled d-orbitals in their atoms or in one of their oxidation states.
Examples
Iron (Fe)
Cobalt (Co)
Nickel (Ni)
Non-Transition Elements
Although Zn, Cd, and Hg belong to the d-block, they are not considered transition elements because they possess completely filled d-orbitals.
General Characteristics of Transition Elements
1. Metallic Nature
Transition elements are hard, lustrous metals with high melting and boiling points.
2. Variable Oxidation States
Transition elements show multiple oxidation states due to the involvement of both ns and (n−1)d electrons.
Examples
Iron: +2, +3
Manganese: +2 to +7
Chromium: +2, +3, +6
3. Formation of Colored Ions
Many transition metal ions are colored because of d-d electronic transitions.
Examples
| Ion | Colour |
|---|---|
| Cu²⁺ | Blue |
| Fe³⁺ | Yellow-Brown |
| Cr³⁺ | Green |
| MnO₄⁻ | Purple |
4. Paramagnetic Nature
Most transition elements possess unpaired electrons and therefore exhibit paramagnetism.
5. Catalytic Properties
Many transition metals and their compounds act as catalysts.
Examples
Fe in Haber Process
V₂O₅ in Contact Process
Ni in Hydrogenation
Daily Practice Problems (DPP)
📝 Download d- and f-Block Elements DPP
Electronic Configuration of Transition Elements
General Configuration
(n − 1)d¹–¹⁰ ns⁰–²
Examples
Scandium (Sc)
3d¹ 4s²
Iron (Fe)
3d⁶ 4s²
Copper (Cu)
3d¹⁰ 4s¹
Important Trends in Transition Elements
Atomic Radius
Atomic radii show only a slight decrease across a transition series.
Ionization Enthalpy
Ionization enthalpies increase gradually across the period.
Density
Transition elements generally possess high densities.
Examples:
Osmium
Iridium
Potassium Dichromate (K₂Cr₂O₇)
Potassium dichromate is an important compound of chromium.
Properties
Orange crystalline solid
Strong oxidizing agent
Uses
Laboratory oxidizing agent
Organic synthesis
Titrations
Potassium Permanganate (KMnO₄)
Potassium permanganate is an important compound of manganese.
Properties
Purple crystalline solid
Powerful oxidizing agent
Uses
Water treatment
Disinfectant
Analytical chemistry
The f-Block Elements
The elements in which the last electron enters the f-subshell are called f-block elements.
They are placed separately at the bottom of the periodic table.
Types of f-Block Elements
1. Lanthanoids
Atomic Numbers:
58–71
From Cerium (Ce) to Lutetium (Lu)
2. Actinoids
Atomic Numbers:
90–103
From Thorium (Th) to Lawrencium (Lr)
Characteristics of Lanthanoids
Lanthanoid Contraction
The gradual decrease in atomic and ionic radii across the lanthanoid series is called lanthanoid contraction.
Causes
Poor shielding effect of 4f electrons.
Consequences of Lanthanoid Contraction
Similarity between Zr and Hf
Difficulty in separation of lanthanoids
Variation in basic strength
Characteristics of Actinoids
Properties
Radioactive nature
Variable oxidation states
Complex formation
Greater reactivity
Common Oxidation States
+3, +4, +5, +6
Applications of d- and f-Block Elements
Industrial Applications
Catalysts
Alloy manufacturing
Stainless steel production
Biological Applications
Iron in hemoglobin
Cobalt in Vitamin B₁₂
Nuclear Applications
Uranium in nuclear reactors
Thorium as nuclear fuel
Practice Exercises & Assignments
📖 Download d- and f-Block Elements Practice Questions
Important Points for Quick Revision
✔ Transition elements have partially filled d-orbitals.
✔ They exhibit variable oxidation states.
✔ Many transition metal ions are colored.
✔ Transition elements show catalytic activity.
✔ Lanthanoid contraction is a key concept.
✔ Actinoids are radioactive.
✔ KMnO₄ and K₂Cr₂O₇ are important oxidizing agents.
NEET & JEE Quick Revision
✔ Cu²⁺ → Blue colour
✔ KMnO₄ → Purple colour
✔ K₂Cr₂O₇ → Orange colour
✔ Lanthanoid contraction occurs due to poor shielding.
✔ Transition metals show variable oxidation states.
✔ Many transition metals are paramagnetic.
Frequently Asked Questions (FAQs)
Q1. Why are transition metal ions colored?
Because of d-d electronic transitions.
Q2. What is lanthanoid contraction?
The gradual decrease in atomic and ionic radii across the lanthanoid series.
Q3. Which compounds are important oxidizing agents?
KMnO₄
K₂Cr₂O₇
Q4. Why is this chapter important for NEET and JEE?
It contains many direct NCERT-based questions and conceptual inorganic chemistry topics.
Conclusion
The d- and f-Block Elements chapter is one of the most important units in Inorganic Chemistry. Understanding transition metals, lanthanoids, actinoids, oxidation states, colored ions, magnetic properties, and important compounds such as KMnO₄ and K₂Cr₂O₇ is essential for scoring well in NEET, JEE Main, JEE Advanced, and Board Examinations.
Regular revision of NCERT tables, oxidation states, and important reactions will help students master this chapter effectively.
Stay connected with Chemistry Achievers Academy for free notes, DPPs, MCQs, PYQs, formula sheets, and chapter-wise study materials for NEET, JEE, CSIR NET, TN SET, and PG TRB examinations.
Comments
Post a Comment