Chemistry · JEE Advanced only

p-Block Elements: Detailed Compound Chemistry (JEE Advanced)

Not in the JEE Main syllabus, but it is in JEE Advanced. Study time: about 18-25 hours. This is one of the most content-heavy topics in inorganic chemistry. You need to memorize many reactions, structures, and properties. Spread it over 2-3 weeks, doing one group at a time, with regular revision..

Last updated: 26 October 2026

Direct answer

p-Block compound chemistry covers the preparation, properties, reactions, and uses of specific compounds from Groups 13 to 18.

p-Block compound chemistry covers the preparation, properties, reactions, and uses of specific compounds from Groups 13 to 18. You need to know reaction mechanisms, structures, acidic or basic nature, and industrial processes for compounds like borax, diborane, ammonia, sulfuric acid, and xenon fluorides. This topic tests your ability to connect structure with reactivity and recall specific chemical behaviors.

Official syllabus

What the JEE Advanced syllabus says

“Group 13: Reactivity towards acids, alkalis, and halogens; preparation, properties, and uses of borax, orthoboric acid, diborane, boron trifluoride, aluminium chloride, and alums; uses of boron and aluminium. Group 14: Reactivity towards water and halogen; allotropes of carbon and uses of carbon; preparation, properties, and uses of carbon monoxide, carbon dioxide, silicon dioxide, silicones, silicates, zeolites. Group 15: Reactivity towards hydrogen, oxygen, and halogen; allotropes of phosphorous; preparation, properties, and uses of dinitrogen, ammonia, nitric acid, phosphine, phosphorus trichloride, phosphorus pentachloride; oxides of nitrogen and oxoacids of phosphorus. Group 16: Reactivity towards hydrogen, oxygen, and halogen; simple oxides; allotropes of sulphur; preparation/manufacture, properties, and uses of dioxygen, ozone, sulphur dioxide, sulfuric acid; oxoacids of sulphur. Group 17: Reactivity towards hydrogen, oxygen, and metals; preparation/manufacture, properties, and uses of chlorine, hydrogen chloride and interhalogen compounds; oxoacids of halogens, bleaching powder. Group 18: Chemical properties and uses; compounds of xenon with fluorine and oxygen”

Source: JEE Advanced 2026 Information Bulletin, Annexure-I. Closest JEE Main topic: General Introduction: Electronic configuration and general trends in physical and chemical properties of elements across the periods and down the groups.

JEE Main covers only general trends and electronic configurations of p-block elements, not the detailed chemistry of individual compounds. Advanced demands you know specific preparations, reactions, structures, and uses of about 30+ compounds across six groups.

Key ideas

What you must understand

Master the structures first: diborane has 3-center-2-electron bonds, PCl5 has trigonal bipyramidal geometry, SF6 is octahedral, XeF2 is linear with 3 lone pairs
Learn preparations as balanced equations: Contact process for H2SO4, Ostwald process for HNO3, Haber process for NH3, electrolysis of brine for Cl2
Understand acidic and basic oxides: CO2 and SO2 are acidic, N2O is neutral, NO2 dimerizes to N2O4
Know the oxoacids and their structures: phosphorus has H3PO4, H3PO3, H3PO2 with different basicities based on P-H bonds
Interhalogen compounds follow the formula AXn where n = 1, 3, 5, or 7 and the central atom is always the larger halogen
Xenon compounds exist because Xe has low ionization energy among noble gases and F2 and O are highly electronegative

Formulas

Formulas and key facts

Borax + HCl → H3BO3 + NaCl (orthoboric acid preparation)
B2H6 + 6H2O → 2H3BO3 + 6H2 (diborane hydrolysis)
4NH3 + 5O2 → 4NO + 6H2O (Ostwald process, Pt catalyst, 500°C)
2SO2 + O2 ⇌ 2SO3 (Contact process, V2O5 catalyst, 450°C)
Ca(OCl)Cl → bleaching powder, mixed salt not CaCl2 + Ca(OCl)2
XeF2 + H2O → Xe + 2HF + ½O2 (hydrolysis of xenon difluoride)
H3PO3 is dibasic (one P-H bond), H3PO2 is monobasic (two P-H bonds)
AlCl3 exists as Al2Cl6 dimer in vapor phase due to electron deficiency

Avoid

Common mistakes

Confusing the basicity of phosphorus oxoacids: H3PO4 is tribasic, H3PO3 is dibasic, H3PO2 is monobasic. Count O-H bonds, not total H atoms.
Forgetting that PCl5 in solid state is ionic [PCl4]+[PCl6]- but covalent in gas and liquid phases.
Mixing up bleaching powder formula: it is Ca(OCl)Cl, a mixed salt, not a simple mixture of calcium chloride and hypochlorite.
Assuming all nitrogen oxides are acidic: N2O is neutral, NO is neutral, only NO2 and higher oxides are acidic.

Worked example

A JEE Advanced-level example

Question. Phosphorus acid (H3PO3) is heated. Write the products formed and calculate the mass of phosphine produced when 16.4 g of H3PO3 is heated completely.

Show solution

Write the thermal decomposition reaction: 4H3PO3 → 3H3PO4 + PH3. On heating, phosphorous acid disproportionates to phosphoric acid and phosphine.
Calculate molar mass of H3PO3: M = 3(1) + 31 + 3(16) = 3 + 31 + 48 = 82 g/mol
Find moles of H3PO3: n = 16.4/82 = 0.2 mol
From stoichiometry, 4 mol H3PO3 gives 1 mol PH3. So 0.2 mol H3PO3 gives 0.2/4 = 0.05 mol PH3
Calculate mass of PH3: Molar mass of PH3 = 31 + 3(1) = 34 g/mol. Mass = 0.05 × 34 = 1.7 g

Answer: Products are H3PO4 and PH3. Mass of phosphine produced = 1.7 g

Solved twice independently; both solutions agree.

FAQs

Frequently asked questions

Is p-Block Elements: Detailed Compound Chemistry in the JEE Main syllabus?

No. It is in the JEE Advanced 2026 syllabus only. The closest JEE Main topic is General Introduction: Electronic configuration and general trends in physical and chemical properties of elements across the periods and down the groups.

How long does p-Block Elements: Detailed Compound Chemistry take to prepare for JEE Advanced?

About 18-25 hours. This is one of the most content-heavy topics in inorganic chemistry. You need to memorize many reactions, structures, and properties. Spread it over 2-3 weeks, doing one group at a time, with regular revision., if you already know the related JEE Main topic.