Exam Master Review Sheet - p-Block Elements

CHEMCA

EXAM MASTER REVIEW SHEET

The p-Block Elements (Groups 13-18)

Strategic Revision for JEE Main, Advanced & NEET

1. General Characteristics & Key Effects

Inert Pair Effect

The reluctance of \(ns^2\) electrons to participate in bonding due to poor shielding by d and f orbitals.

Stability Trend:
• Gr 13: \(Tl^+\) > \(Tl^{3+}\)
• Gr 14: \(Pb^{2+}\) > \(Pb^{4+}\)
• Gr 15: \(Bi^{3+}\) > \(Bi^{5+}\)

Anomalous Properties

First element of each group (B, C, N, O, F) is anomalous due to:
• Smallest size
• High EN & IE
• Absence of vacant d-orbitals (Max covalency = 4)

2. Boron & Carbon Families

Boranes (\(B_2H_6\)) Group 13

Contains 2-electron, 3-center bonds (Banana Bonds).

\(4 \times (2e^-, 2c)\) bonds
\(2 \times (2e^-, 3c)\) bonds

Allotropes of Carbon Group 14

• • Diamond: \(sp^3\), Hardest, Insulator
• • Graphite: \(sp^2\), Soft, Lubricant, Conductor
• • Fullerenes: \(C_{60}\) (Buckminsterfullerene)

3. Nitrogen & Oxygen Families

Oxoacids of Phosphorus

• • \(H_3PO_2\): Hypophosphorous (Monobasic)
• • \(H_3PO_3\): Phosphorous (Dibasic)
• • \(H_3PO_4\): Orthophosphoric (Tribasic)
• *Basicity = Number of P-OH bonds*

Oxoacids of Sulfur

• • \(H_2SO_4\): Sulphuric Acid (Oil of Vitriol)
• • \(H_2S_2O_7\): Oleum (Pyrosulphuric)
• • \(H_2S_2O_8\): Marshall's Acid (Peroxo link)
• • \(H_2SO_5\): Caro's Acid (Peroxymonosulphuric)

4. Halogens & Noble Gases

Anomalous Trends in Halogens

Electron Gain Enthalpy

\(Cl > F > Br > I\)

Bond Dissoc. Enthalpy

\(Cl_2 > Br_2 > F_2 > I_2\)

Xenon Compound	Structure / Geometry	Lone Pairs on Xe
\(XeF_2\)	Linear	3
\(XeF_4\)	Square Planar	2
\(XeF_6\)	Distorted Octahedral	1
\(XeO_3\)	Pyramidal	1

5. Must-Know Reactions

Nitrogen Fixation (Haber's):

\[ N_2(g) + 3H_2(g) \xrightarrow[700K]{\text{Fe/Mo}} 2NH_3(g) \quad (\Delta H < 0) \]

Equilibrium Symbol: \(\rightleftharpoons\)

Contact Process (Sulfuric Acid): \[ 2SO_2 + O_2 \xrightarrow{V_2O_5} 2SO_3 \quad | \quad SO_3 + H_2SO_4 \to H_2S_2O_7 \]

Action of HNO\(_3\) on Copper:

Dilute: \(NO\) gas

Conc: \(NO_2\) gas

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