d & f Block Elements Class 12 Handwritten Notes - Download PDF

Ans. You can download the d- and f-Block Elements Class 12 Chemistry Handwritten Notes PDF directly from this page. Both the Normal and HD versions are available, and both are free.

Ans. Yes. The notes follow the current 2026-27 syllabus for Class 12 Chemistry, where The d- and f-Block Elements is Chapter 4. The chapter was kept intact in the new NCERT edition, so every trend, oxidation-state grid, reagent preparation, and lanthanoid-contraction explanation in the PDF matches the 2026-27 textbook.

Ans. The Handwritten Notes PDF runs 22 pages and covers position and electronic configuration, atomic and ionic radii, ionisation enthalpy, oxidation states, standard electrode potentials, colour and magnetic moment, preparation and properties of K₂Cr₂O₇ and KMnO₄, lanthanoid contraction, and the lanthanoid versus actinoid comparison.

Ans. Zn has the electronic configuration [Ar] 3d¹⁰ 4s² in the atomic state and 3d¹⁰ in the Zn²⁺ ion state. Because its d-orbitals are completely filled in both the atomic and the common ion form, it does not show the typical transition-metal properties of variable oxidation state, colour from d-d transition, or paramagnetism, so it is excluded from the transition series. Cd and Hg are excluded for the same reason.

Ans. Lanthanoid contraction is the steady decrease in atomic and ionic radius across the lanthanoid series from Ce to Lu, caused by the poor shielding of 4f electrons. Its main consequence is that the elements of the second (4d) and third (5d) transition series have nearly identical atomic radii. Zr and Hf are the textbook example: their atomic radii differ by less than 1 pm, which makes their separation chemically difficult.

Ans. The chapter contributes 2 to 3 per cent of JEE Main Chemistry, with at least one question on colour, magnetic moment, or oxidising action of KMnO₄ in every shift. NEET asks two to three questions per year, typically one on lanthanoid contraction and one on oxidation states. The chapter is also a prerequisite for Coordination Compounds (Chapter 5), so locking it well saves study time on the next chapter.

Ans. Use the 8-point Last 24-Hour Revision Card in the Collegedunia Handwritten Notes. Focus on the four highest-yield items: the spin-only magnetic-moment formula, the acidic-medium half-cell equations for K₂Cr₂O₇ and KMnO₄, the lanthanoid-contraction reasoning, and the actinoid versus lanthanoid comparison. The card takes 11 to 13 minutes end to end.

Ans. Cr (Z = 24) is [Ar] 3d⁵ 4s¹ and Cu (Z = 29) is [Ar] 3d¹⁰ 4s¹. Half-filled (d⁵) and fully-filled (d¹⁰) d-subshells are extra-stable due to maximum exchange energy and symmetrical electron distribution, so the 4s electron promotes to 3d. The handwritten notes ring this Cr-Cu anomalous configuration in red ink on the 3d series electron config table.

Ans. KMnO₄ preparation is drawn as an arrow flowchart on page 17 (Fig 4.10). The route starts from pyrolusite (MnO₂), fuses with KOH and O₂ to give green K₂MnO₄, then disproportionates in neutral/acidic medium to purple KMnO₄. The properties card lists the n-factor in three media (5/3/1 in acidic/neutral/strongly alkaline) and the standard E°(MnO₄^-/Mn²⁺) = +1.51 V.

Ans. K₂Cr₂O₇ preparation is on page 15 (Fig 4.9). Chromite ore (FeCr₂O₄) is roasted with Na₂CO₃ in air, the resulting Na₂CrO₄ is acidified to dichromate, then treated with KCl to crystallise K₂Cr₂O₇. The orange-to-yellow chromate-dichromate equilibrium colour shift is sketched alongside the acidic-medium half-cell.

Ans. The chromate-dichromate equilibrium is the pH-controlled 2CrO₄^2- + 2H⁺ Cr₂O₇^2- + H₂O . Adding acid pushes the equilibrium right, turning the solution orange. Adding base pushes it left, restoring the yellow colour. The handwritten notes mark this colour pair on the K₂Cr₂O₇ page using orange and yellow highlighter strips.

Ans. Fig 4.13 on page 21 compares actinoids vs lanthanoids on four axes: oxidation-state range (+3 dominant for Ln vs up to +7 for An), radioactivity (none for Ln vs all radioactive for An), shielding (4f vs weaker 5f, so actinoid contraction is larger per element), and colour (Ln³⁺ mostly faintly coloured, An³⁺ more intensely coloured).

Ans. The catalytic activity of transition metals comes from variable oxidation states (electron exchange in a reaction cycle) and partially filled d-orbitals (adsorption sites for reactants on the catalyst surface). The handwritten notes summarise the textbook examples on a single card: Fe in Haber, V₂O₅ in Contact, Ni in hydrogenation, and Pt in catalytic converters.

Ans. Interstitial compounds are non-stoichiometric solids in which small atoms (H, C, N, B) occupy lattice voids of transition metals, giving hard, high-melting, chemically inert materials like TiC, Mn₄N and VH. Alloy formation is favoured because transition metals have similar atomic radii. The handwritten notes list four key alloys: brass (Cu-Zn), bronze (Cu-Sn), stainless steel (Fe-Cr-Ni) and misch metal (95% Ln + 5% Fe).