Applications of d- and f-block elements
NCERT Class 12 Chemistry Chapter 4 Section 4.7
Quick answer
The d-block elements supply structural metals, alloys, catalysts, pigments, battery materials and light-sensitive compounds. Their uses depend on properties such as strong bonding, accessible oxidation states and interactions with reactants. Examples include iron in steel and ammonia synthesis, nickel in hydrogenation, titanium dioxide as a white pigment and palladium compounds in the Wacker process.
With your textbook
NCERT Chemistry Part I (Class 12), Chapter 4 “The d- and f-Block Elements”, Section 4.7 “Some Applications of d- and f-Block Elements”, pages 113–114.
Open the official NCERT chapter (PDF, 4.2 MB, ncert.nic.in) (opens in a new tab)
Checked against the 2026-27 reprint on .
What are the applications of the d- and f-block elements?
Applications of the d- and f-block elements
The transition metals and their compounds are everywhere in industry: as structural metals, as special-purpose compounds such as pigments and battery materials, and above all as catalysts. NCERT begins with the most important:
Iron and steels are the most important construction materials.
NCERT Chemistry Part I (Class 12), Section 4.7, page 113
In plain words: the same properties met earlier in the chapter (strong metallic bonding, several oxidation states, coloured and complex-forming ions) are what make these elements useful. Steel uses their strength; catalysts use their ability to change oxidation state and bind molecules to a surface.
Iron and steels
- Making steel. Iron and steel production rests on the reduction of iron oxides, the removal of impurities, and control of the carbon content and addition of suitable alloying metals such as chromium, manganese and nickel (NCERT Section 4.7, page 113).
- Lanthanoids in steel. NCERT calls the production of alloy steels for plates and pipes “the best single use of the lanthanoids”; give that in an exam. Mischmetall, mostly lanthanoid metal with about 5% iron, goes into magnesium-based alloys for bullets, shells and lighter flints (NCERT page 111).
Compounds for special purposes
- Pigment and batteries. NCERT names TiO for the pigment industry and MnO2 for dry battery cells; the battery industry also needs zinc and nickel/cadmium (NCERT page 113). In the dry cell, the MnO2 packed round the graphite cathode is what is reduced (NCERT Class 12 Chemistry, Unit 2, page 54).
- Phosphors. Some individual lanthanoid oxides are phosphors in television screens and similar fluorescing surfaces (NCERT page 111).
- NCERT slip (page 113): the pigment is printed “TiO”. Beyond the NCERT text: the white pigment is titanium dioxide, TiO2, called titanium white when used as a pigment (Wikipedia, “Titanium dioxide”). In an exam, write TiO2.
- Coinage metals. The group 11 metals, copper, silver and gold, are still worth calling coinage metals, though silver and gold are now restricted to collection items; NCERT adds that the UK ‘copper’ coins are copper-coated steel and the ‘silver’ coins a Cu/Ni alloy (NCERT pages 113–114); give that in an exam. Beyond the NCERT text: 1p and 2p coins are copper-plated steel, and 5p and 10p coins have been issued in nickel-plated steel since 2012 (Wikipedia, “Coins of the pound sterling”), so NCERT’s ‘silver’ coin statement is now dated, and colour alone does not identify a copper–nickel alloy.
- Silver-halide film photography relies on the light-sensitive properties of silver bromide, AgBr (NCERT page 114).
Catalysts in industry
Many of the metals and their compounds are essential industrial catalysts (NCERT page 114):
| Process | Catalyst |
|---|---|
| SO2 oxidised in making sulphuric acid (Contact process; NCERT page 104) | V2O5 |
| Polythene (Ziegler catalysts) | TiCl4 with Al(CH3)3 |
| NH3 from N2 and H2 (Haber) | iron |
| Hydrogenation of fats | nickel |
| Ethene to ethanal (Wacker) | PdCl2 with CuCl2 and oxygen for catalyst regeneration |
| Polymerising alkynes | nickel complexes |
| Petroleum cracking | mixed lanthanoid oxides (NCERT page 111) |
- Nickel complexes “are useful in the polymerisation of alkynes and other organic compounds such as benzene” (NCERT page 114); quote that in an exam. Beyond the NCERT text: nickel compounds catalyse the cyclotrimerisation of alkynes to benzene rings, 3C2H2 → C6H6, as Reppe reported in 1948 (Wikipedia, “Alkyne trimerisation”), so do not read NCERT’s sentence as saying that benzene itself is polymerised (reasoned).
- NCERT slip (page 114): the Wacker process is printed as “the oxidation of ethyne to ethanal”. Beyond the NCERT text: the Wacker process oxidises ethene (ethylene) to ethanal (acetaldehyde), with palladium(II) chloride and copper(II) chloride as catalysts; before that process, ethanal was made from ethyne (Wikipedia, “Wacker process”). Ethyne to ethanal would not even be an oxidation (Example 2). In an exam, write ethene.
- NCERT slip (page 114): the Ziegler catalyst’s aluminium compound is printed “A1(CH3)3”, with the digit 1 for the letter l. Read it as Al(CH3)3, trimethylaluminium.
- Why they work, from earlier in the chapter: transition metals adopt several oxidation states and bind reactant molecules at their surface (NCERT Section 4.3.12, page 104).
Solved examples
Example 1: Oxidation states in the catalysts
Find the oxidation state of the metal in V2O5, TiCl4 and PdCl2.
Answer: V2O5: 2x − 10 = 0, +5. TiCl4: x − 4 = 0, +4. PdCl2: x − 2 = 0, +2 (reasoned).
Example 2: Is ethyne to ethanal an oxidation?
Find the average oxidation number of carbon in ethene (C2H4), ethyne (C2H2) and ethanal (CH3CHO, C2H4O). Which change does the Wacker process carry out?
Answer: With H +1 and O −2: ethene 2x + 4 = 0, x = −2; ethyne 2x + 2 = 0, x = −1; ethanal 2x + 4 − 2 = 0, x = −1. Ethene → ethanal raises carbon from −2 to −1, an oxidation, which is what the Wacker process does. Ethyne → ethanal leaves the average at −1: it is the addition of water, not an oxidation (reasoned).
Example 3: Why titanium dioxide is white
Explain why TiO2 makes a white pigment.
Answer: Titanium is +4 in TiO2 (x − 4 = 0), so Ti4+ is 3d and has no d–d transition, like the colourless Ti4+ in NCERT Table 4.8 (page 103). That alone does not make a solid white, because d permanganate is intensely coloured (NCERT page 107). Beyond the NCERT text: Pure pigment-grade TiO2 absorbs little visible light; its particles scatter visible wavelengths strongly because of their high refractive index, making the powder white (Wikipedia, “Titanium dioxide”).
Common mistakes to avoid
Common mistake
Writing TiO as the white pigment
The pigment is TiO2, titanium(IV) oxide; NCERT’s “TiO” is a misprint.
Common mistake
Making ethyne the Wacker substrate
The Wacker process oxidises ethene to ethanal with PdCl2. Ethyne gives ethanal by adding water, which is not an oxidation.
Common mistake
Mixing up the catalysts
V2O5 for sulphuric acid, iron for ammonia, nickel for hydrogenating fats, TiCl4 with Al(CH3)3 for polythene, PdCl2 for ethanal.
Quick revision summary
- Iron and steels are the main construction materials: oxides reduced, impurities removed, carbon and Cr, Mn, Ni added.
- Special compounds: TiO (pigment; NCERT prints TiO), MnO (dry cells), Zn and Ni/Cd (batteries), AgBr (photography), Ln oxides (phosphors); group 11 coinage metals.
- Catalysts: VO (sulphuric acid), TiCl + Al(CH) (Ziegler, polythene), Fe (Haber), Ni (hydrogenation), PdCl (Wacker, ethene → ethanal), mixed Ln oxides (cracking).
Formula sheet
- Contact process catalyst: VO (V +5)
- Haber process catalyst: Fe
- Ziegler catalyst: TiCl + Al(CH)
- Wacker process: ethene → ethanal, PdCl
- Hydrogenation of fats: Ni
Questions students ask
What is stainless steel made of, and how is it different from ordinary steel?
Stainless steel is iron alloyed with chromium and usually nickel, while ordinary steel is iron hardened by a little carbon: NCERT Class 10 Science notes that about 0.05% carbon makes iron hard and strong, and that “When iron is mixed with nickel and chromium, we get stainless steel, which is hard and does not rust” (Chapter 3, page 54). Beyond the NCERT text, the commonest grade, type 304 or “18/8”, holds 18–20% chromium and 8–11% nickel with at most 0.08% carbon (Wikipedia, “SAE 304 stainless steel”). A chromium-rich passive surface film gives corrosion resistance, but stainless steel can still corrode under unsuitable conditions; as the corrosion page explains.
What are the actinoids used for?
The actinoids are used mainly for their nuclear properties, which NCERT’s Section 4.7 does not cover (beyond the NCERT text from here). Uranium-235 and plutonium-239 fuel fission reactors, and India plans to use the thorium of its coastal monazite sands by breeding uranium-233 from thorium-232 (Wikipedia, “Actinide” and “India’s three-stage nuclear power programme”). Most ionisation smoke detectors hold one microcurie or less of americium-241, whose alpha particles ionise the air inside (US Nuclear Regulatory Commission), and the heat of decaying plutonium-238 powers spacecraft such as the Voyagers (US Department of Energy).
What are the lanthanoids used for today?
Today the lanthanoids go into magnets, lighting, catalytic converters and medicine as well as NCERT’s alloy steels, mischmetall, cracking catalysts and television phosphors (NCERT page 111; the newer uses are beyond the NCERT text). Neodymium–iron–boron magnets may also contain praseodymium, dysprosium or terbium, depending on the grade, and europium gives the red phosphor of television screens and phosphors for fluorescent lamps (Wikipedia, “Rare-earth element”); cerium(IV) oxide is an oxidation catalyst in catalytic converters (Wikipedia, “Lanthanide”). Gadolinium complexes are MRI contrast agents, because Gd3+, 4f7, has seven unpaired electrons with parallel spins (same source).
Are the applications of d- and f-block elements in the JEE Main and NEET syllabus?
The section title is not listed as a standalone heading in JEE Main 2027 or NEET (UG) 2026, but several applications are directly relevant: Unit 11 of both lists the transition elements’ catalytic behaviour and alloy formation, and the uses of K2Cr2O7 and KMnO4, so relevant catalyst and alloy examples should still be studied. The section is in the CBSE Class XII syllabus for 2026–27, whose Unit 4 ends with “Some Applications of d- and f- Block Elements”, so it counts for the board exam. The catalysts are explained on the general properties page.
Practice questions
Try each question first, then open the answer to check your working.
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Q1. Name the catalyst used in (a) the manufacture of sulphuric acid, (b) the Haber process and (c) the hydrogenation of fats.
Show answerHide answer
(a) V2O5, (b) iron, (c) nickel (NCERT page 114).
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Q2. Which transition-metal compound does the photographic industry rely on, and why?
Show answerHide answer
Silver bromide, AgBr, for its special light-sensitive properties (NCERT page 114).
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Q3. Which metals are added to steel as alloying metals, and what are mixed lanthanoid oxides used for?
Show answerHide answer
Chromium, manganese and nickel (NCERT page 113). Mixed lanthanoid oxides are catalysts in petroleum cracking (NCERT page 111).