What is the Weightage of d and f Block Elements Class 12 Chemistry?
By ConceptScroll Team · Published on 18 June 2026 · 4 min read
The weightage of d and f block elements class 12 in Chemistry is significant for CBSE exams. This chapter covers essential concepts from the NCERT textbook, helping students score well by focusing on important topics and practicing exercises.
Overview of d and f Block Elements in Class 12 Chemistry
The d- and f-block elements form an important chapter in the Class 12 NCERT Chemistry syllabus. These elements are part of the transition and inner transition metals, respectively.
- d-block elements are found in groups 3 to 12 of the periodic table. They are also called transition elements because they exhibit typical metallic properties and variable oxidation states.
- f-block elements include lanthanoids and actinoids, placed separately at the bottom of the periodic table.
This chapter explains their electronic configurations, general properties, and specific chemical behaviour, which are crucial for understanding modern inorganic chemistry.
What is the Weightage of d and f Block Elements Class 12 in Exams?
Understanding the weightage of d and f block elements class 12 helps students allocate study time effectively. Typically, this chapter carries around 12-15% of the total marks in the CBSE Class 12 Chemistry exam.
- Questions range from definitions, electronic configurations, and properties to chemical reactions.
- Both objective and subjective questions appear, including numerical problems and theoretical explanations.
- NCERT exercises and exemplar problems from this chapter are frequently asked in exams.
Focusing on this chapter can significantly boost your overall Chemistry score.
Want to test yourself on The d- and f-Block Elements? Try our free quiz →
Key Concepts to Focus on for d and f Block Elements
To excel in the d- and f-block elements chapter, students should concentrate on the following core concepts:
- Electronic Configuration: Understand how electrons fill the d and f orbitals.
- Oxidation States: Variable oxidation states in transition metals and typical states in lanthanoids/actinoids.
- General Properties: Metallic character, magnetic properties, catalytic behaviour.
- Chemical Reactivity: Reactions with oxygen, halogens, and acids.
- Important Compounds: Preparation and uses of compounds like KMnO₄, K₂Cr₂O₇, and organometallic compounds.
Mastering these topics ensures clarity and confidence during exams.
Comparison Between d-Block and f-Block Elements
Here is a comparison table highlighting the main differences between d-block and f-block elements:
| Feature | d-Block Elements | f-Block Elements |
|---|---|---|
| Position in Periodic Table | Groups 3-12, middle block | Lanthanoids and Actinoids, bottom block |
| Electron Filling | Filling of (n-1)d orbitals | Filling of 4f and 5f orbitals |
| Oxidation States | Multiple variable states | Mostly +3 oxidation state |
| Magnetic Properties | Often paramagnetic | Strongly paramagnetic |
| Occurrence | Transition metals like Fe, Cu, Zn | Rare earth elements |
| Chemical Reactivity | High catalytic activity | Less reactive, radioactive actinoids |
This comparison helps in quick revision and understanding of their unique characteristics.
Solved Example: Calculating Oxidation State in d-Block Elements
Let's solve a typical problem related to the oxidation state of a d-block element:
Example: Determine the oxidation state of chromium in potassium dichromate ($K_2Cr_2O_7$).
Solution:
- The compound formula is $K_2Cr_2O_7$.
- Potassium ($K$) has an oxidation state of +1.
- Oxygen ($O$) has an oxidation state of -2.
Let the oxidation state of chromium be $x$.
The sum of oxidation states in a neutral compound is zero, so:
$$2(+1) + 2x + 7(-2) = 0$$ $$2 + 2x - 14 = 0$$ $$2x - 12 = 0$$ $$2x = 12$$ $$x = +6$$
Answer: Chromium is in the +6 oxidation state in potassium dichromate.
This type of question is commonly asked in Class 12 Chemistry exams.
Tips to Prepare for the d- and f-Block Elements Chapter
To score well in the d- and f-block elements chapter, follow these preparation tips:
- Understand Concepts: Focus on understanding electronic configurations and properties rather than rote memorization.
- Use NCERT Textbook: Complete all exercises and solved examples in the NCERT Class 12 Chemistry book.
- Practice Diagrams: Learn the layout of the periodic table showing d- and f-block elements.
- Revise Important Formulas: For example, oxidation state calculations and magnetic moment formulas.
- Solve Previous Year Papers: This helps identify frequently asked questions and exam patterns.
Consistent practice and conceptual clarity will improve your performance in this chapter.
Frequently asked questions
What is the weightage of d and f block elements in Class 12 Chemistry exams?
The d and f block elements chapter carries approximately 12-15% weightage in Class 12 Chemistry exams.
Which elements are included in the d-block and f-block?
d-block elements are transition metals in groups 3-12; f-block elements include lanthanoids and actinoids.
Why are d-block elements called transition elements?
Because they show variable oxidation states and form coloured compounds, indicating transition between states.
Are f-block elements important for Class 12 Chemistry exams?
Yes, f-block elements are important and often appear in questions related to electronic configuration and properties.
How can I prepare effectively for the d and f block elements chapter?
Focus on NCERT exercises, understand concepts, practice oxidation state problems, and revise diagrams regularly.
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