The p-Block Elements (Group 13–18)
1. Introduction to p-Block Elements
p-Block elements are those in which the last electron enters the p-orbital.
They belong to Groups 13 to 18 of the periodic table.
General electronic configuration:
$$ns^2\,np^{1-6}$$
2. General Trends in p-Block
Atomic & Ionic Radii
Atomic radius decreases across a period and increases down a group due to
increase in nuclear charge and addition of shells.
Ionization Enthalpy
Ionization enthalpy generally increases across a period due to increase in
effective nuclear charge.
Electronegativity
Electronegativity increases across a period and decreases down a group.
3. Group 13 – Boron Family
Elements
B, Al, Ga, In, Tl
Electronic Configuration
$ns^2 np^1$
Oxidation States
Common oxidation state is +3.
Heavier elements show +1 due to inert pair effect.
Important Compounds
Borax: $\mathrm{Na_2B_4O_7 \cdot 10H_2O}$
Boric Acid: $\mathrm{H_3BO_3}$
Boric acid is a Lewis acid, not a proton donor.
4. Group 14 – Carbon Family
Elements
C, Si, Ge, Sn, Pb
Oxidation States
Common oxidation states are +4 and +2.
Stability of +2 increases down the group.
Important Compounds
Carbon dioxide: $\mathrm{CO_2}$
Silicon dioxide: $\mathrm{SiO_2}$
$\mathrm{SiO_2}$ has a giant covalent structure.
5. Group 15 – Nitrogen Family
Elements
N, P, As, Sb, Bi
Oxidation States
Oxidation states vary from –3 to +5.
Ammonia
$\mathrm{N_2 + 3H_2 \rightarrow 2NH_3}$
Ammonia has trigonal pyramidal geometry and lone pair on nitrogen.
6. Group 16 – Oxygen Family
Elements
O, S, Se, Te, Po
Oxidation States
Common oxidation states: –2, +2, +4, +6.
Sulfuric Acid
$\mathrm{H_2SO_4}$
Sulfuric acid is a strong acid and powerful dehydrating agent.
7. Group 17 – Halogens
Elements
F, Cl, Br, I, At
Oxidation States
Halogens show –1 oxidation state; Cl, Br, I also show +1, +3, +5, +7.
Hydrogen Halides
$\mathrm{HX \;(X=F,Cl,Br,I)}$
Acidic strength increases from HF to HI.
8. Group 18 – Noble Gases
Elements
He, Ne, Ar, Kr, Xe, Rn
Electronic Configuration
$ns^2 np^6$ (except He)
Compounds of Xenon
$\mathrm{XeF_2,\; XeF_4,\; XeF_6}$
Noble gases are not completely inert.
9. Inert Pair Effect
The tendency of the outermost $ns^2$ electrons to remain non-bonding.
Increases down the p-block.
10. Anomalous Behaviour of First Element
First element of each group shows anomalous behavior due to:
- Small size
- High electronegativity
- Absence of d-orbitals
11. Important JEE Tips
- Remember oxidation state trends
- Learn important compounds and their structures
- Focus on exceptions (B, C, N, O, F)
12. Final Revision Checklist
You are exam-ready if you can:
- Explain trends across groups
- Predict oxidation states
- Write important reactions
- Compare acidic/basic nature of oxides
- Identify inert pair effect