Introduction to p-Block Elements – II for JEE Main

The chapter p-Block Elements II is a crucial part of Class 12 Chemistry and carries high weightage in JEE Main examinations. This chapter deals with Group 15, 16, 17, and 18 elements, their physical and chemical properties, and important reactions.

Understanding trends, oxidation states, and reactivity patterns is key to answering both conceptual and numerical questions.

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Group 15 Elements – Nitrogen Family

Group 15 elements include Nitrogen (N), Phosphorus (P), Arsenic (As), Antimony (Sb), and Bismuth (Bi).

Key Points:

• Electronic Configuration: ns²np³

• Oxidation States: –3, +3, +5 (varies down the group)

• Allotropy: Nitrogen (N₂ gas), Phosphorus (white, red, black)

• Trends: Electronegativity decreases, metallic character increases

Important Compounds:

• Ammonia (NH₃) – preparation, properties, and reactions

• Phosphine (PH₃) – preparation and properties

• Oxides of nitrogen (N₂O, NO, NO₂, N₂O₅)

Reactions of oxides, acids, and salts are frequently asked in JEE Main.

Group 16 Elements – Oxygen Family

Group 16 elements include Oxygen (O), Sulfur (S), Selenium (Se), Tellurium (Te), Polonium (Po).

Key Points:

• Electronic Configuration: ns²np⁴

• Oxidation States: –2, +2, +4, +6

• Allotropy: Oxygen (O₂, O₃), Sulfur (S₈, rhombic, monoclinic)

• Trends: Electronegativity decreases, metallic character increases

Important Compounds:

• Oxides: SO₂, SO₃, SeO₂

• Acids: H₂SO₄, H₂SO₃

• Sulfides: H₂S, CS₂

Mechanisms of acid-base reactions, redox reactions, and industrial processes like Contact process are important.

Group 17 Elements – Halogens

Group 17 elements include Fluorine (F), Chlorine (Cl), Bromine (Br), Iodine (I), Astatine (At).

Key Points:

• Electronic Configuration: ns²np⁵

• Oxidation States: –1, +1, +3, +5, +7

• Trends: Electronegativity decreases down the group, oxidizing power decreases

Important Compounds:

• Hydrogen halides (HF, HCl, HBr, HI) – properties and reactions

• Interhalogen compounds (ClF, BrF₃)

• Halogen oxides (Cl₂O, ClO₂)

Reactivity:

• Halogens undergo displacement reactions

• Used in bleaching, disinfectants, and industrial chemistry

Group 18 Elements – Noble Gases

Group 18 elements include He, Ne, Ar, Kr, Xe, Rn.

Key Points:

• Electronic Configuration: ns²np⁶ (except He: 1s²)

• Inert nature: Due to complete octet

• Compounds: Mainly xenon fluorides (XeF₂, XeF₄, XeF₆)

Applications:

• Helium – balloons, cooling superconductors

• Argon – inert atmosphere in welding

• Neon – neon signs

JEE Main may ask physical properties, trends, and simple reactions of noble gases.

Trends in p-Block Elements

Key trends across groups:

• Electronegativity: Decreases down the group

• Atomic radius: Increases down the group

• Ionization enthalpy: Decreases down the group

• Oxidation states: More varied in heavier elements

Understanding these trends is essential for predicting chemical reactivity.

Important Reactions in p-Block Elements – II

1. Ammonia and Phosphine Reactions – basicity, formation of salts

2. Oxides and Acids Reactions – acidic/basic nature, redox properties

3. Halogen Displacement and Bleaching Reactions

4. Noble Gas Compounds Formation – mainly xenon chemistry

Mechanism-based and conceptual questions are common in JEE Main.

Applications of p-Block Elements

• Nitrogen: Fertilizers (NH₄NO₃), explosives (TNT)

• Phosphorus: Matches, fertilizers, detergents

• Oxygen & Sulfur: Industrial processes, bleaching, medicine

• Halogens: Disinfectants, pharmaceuticals

• Noble gases: Lighting, cooling, inert atmospheres

Application-oriented questions may appear in JEE Main.

Important JEE Main Preparation Tips for p-Block Elements – II

• Focus on group-wise properties and trends

• Memorize oxidation states, allotropy, and important compounds

• Solve previous year JEE Main questions

• Understand reaction mechanisms and industrial applications

Why Study p-Block Elements – II from Studentbro.in?

Studentbro.in offers:

• Simplified explanations of group properties

• Step-by-step reaction mechanisms

• Tables and charts for quick revision

• MCQs and PYQs aligned with JEE Main syllabus

Conclusion

The p-Block Elements – II chapter is a scoring topic in Class 12 Chemistry for JEE Main. With clear understanding of group properties, trends, and reactions, students can answer both conceptual and application-based questions confidently.

Studentbro.in provides structured, exam-focused content to master p-Block Elements efficiently.