p-Block Elements

Master Groups 13-18 elements, their properties, compounds, and reactions for JEE Chemistry.

p-Block elements (Groups 13-18) include metals, metalloids, and non-metals. This chapter covers their properties and important compounds.

Overview

graph TD
    A[p-Block] --> B[Group 13 - Boron]
    A --> C[Group 14 - Carbon]
    A --> D[Group 15 - Nitrogen]
    A --> E[Group 16 - Oxygen]
    A --> F[Group 17 - Halogens]
    A --> G[Group 18 - Noble Gases]

General Characteristics

  • Valence shell configuration: ns²np¹⁻⁶
  • Show variable oxidation states
  • Include metals, metalloids, and non-metals
  • Form covalent compounds (mostly)

Group 13 (Boron Family)

Elements: B, Al, Ga, In, Tl

Oxidation States: +1, +3 (most common +3)

Boron

  • Metalloid
  • Forms covalent compounds
  • Borax (Na₂B₄O₇·10H₂O) - important compound

Aluminum

  • Most abundant metal in Earth’s crust
  • Amphoteric oxide
  • Extracted by Hall-Héroult process

Group 14 (Carbon Family)

Elements: C, Si, Ge, Sn, Pb

Oxidation States: +2, +4

Carbon

  • Allotropes: Diamond, Graphite, Fullerene
  • Forms multiple bonds (catenation)

Silicon

  • Second most abundant element
  • Used in semiconductors, glass, silicones

Inert Pair Effect

Stability of +2 state increases down the group (Pb²⁺ more stable than Pb⁴⁺)

Group 15 (Nitrogen Family)

Elements: N, P, As, Sb, Bi

Oxidation States: -3, +3, +5

Nitrogen

  • Diatomic (N≡N triple bond)
  • Forms ammonia, nitric acid
  • Industrial: Haber process

Phosphorus

  • Allotropes: White P, Red P, Black P
  • Forms P₄O₁₀ (dehydrating agent)

Group 16 (Oxygen Family)

Elements: O, S, Se, Te, Po

Oxidation States: -2, +2, +4, +6

Oxygen

  • Essential for life
  • Allotropes: O₂, O₃ (ozone)

Sulfur

  • Allotropes: Rhombic, Monoclinic
  • H₂SO₄ - King of chemicals

Group 17 (Halogens)

Elements: F, Cl, Br, I, At

Oxidation States: -1, +1, +3, +5, +7

Properties

  • Most reactive non-metals
  • Reactivity: F > Cl > Br > I
  • Form strong acids (except HF - weak acid)

Interhalogen Compounds

  • AB, AB₃, AB₅, AB₇ type
  • Example: ClF₃, IF₇

Group 18 (Noble Gases)

Elements: He, Ne, Ar, Kr, Xe, Rn

Properties

  • Completely filled valence shell
  • Very low reactivity
  • Form compounds only under extreme conditions (Xe)

Xenon Compounds

  • XeF₂, XeF₄, XeF₆
  • XeO₃, XeOF₄
JEE Tip
Know the structures of important compounds like PCl₅ (trigonal bipyramidal), SF₆ (octahedral), XeF₄ (square planar).

Practice Problems

  1. Why is BCl₃ a Lewis acid while NCl₃ is not?

  2. Explain why nitrogen forms multiple bonds but phosphorus rarely does.

  3. Arrange halogens in order of oxidizing power.

Quick Check
Why does fluorine not show positive oxidation states?

Further Reading