Cheat sheet · JEE Preparation Chemistry
The p-Block Elements cheat sheet
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JEE · Chemistry
Cheat sheet
Entrance syllabus (not in the CBSE books)The p-Block Elements
Inert pair effect: down Groups 13–15 the lower oxidation state (n − 2) becomes more stable — Tl⁺, Pb²⁺, Bi³⁺.
1. Group Trends (13 → 18)
| Group | Outer configuration | Common oxidation states | Notes |
|---|---|---|---|
| 13 (B, Al, Ga, In, Tl) | ns² np¹ | +3, +1 | B is a non-metal; Tl⁺ more stable than Tl³⁺ |
| 14 (C, Si, Ge, Sn, Pb) | ns² np² | +4, +2 | catenation C ≫ Si; Pb²⁺ more stable |
| 15 (N, P, As, Sb, Bi) | ns² np³ | −3, +3, +5 | N forms pπ–pπ bonds; Bi⁵⁺ is a strong oxidant |
| 16 (O, S, Se, Te, Po) | ns² np⁴ | −2, +2, +4, +6 | O is the second most electronegative element |
| 17 (F, Cl, Br, I) | ns² np⁵ | −1 (F only −1) | strong oxidants; F₂ the strongest |
| 18 (He … Rn) | ns² np⁶ | 0 (Xe: +2, +4, +6) | noble gases; Xe forms fluorides/oxides |
2. Group 13 & 14
- Boron: diborane B₂H₆ has 3-centre-2-electron (banana) bonds; boric acid is a weak monobasic Lewis acid.
- BF₃ and AlCl₃ are electron-deficient Lewis acids; AlCl₃ dimerises to Al₂Cl₆.
- Carbon allotropes: diamond (sp³), graphite (sp², conducts), fullerenes (C₆₀).
- CO is a poisonous neutral oxide; CO₂ is acidic. Silicones contain –R₂SiO– units.
3. Group 15
- N₂ is very inert (triple bond, 941 kJ/mol).
- Basicity and stability of hydrides: NH₃ > PH₃ > AsH₃ > SbH₃ > BiH₃ (reducing power increases down).
- Ostwald process: NH₃ → NO → NO₂ → HNO₃ (Pt catalyst).
- White phosphorus is reactive (P₄, glows); red is polymeric and stable.
4. Group 16
- O₂ is paramagnetic; O₃ is a strong oxidant.
- Contact process: SO₂ → SO₃ (V₂O₅), absorbed in H₂SO₄ to form oleum.
- H₂O has the highest boiling point among Group 16 hydrides (H-bonding); acidity H₂O < H₂S < H₂Se < H₂Te.
5. Group 17 & 18
- F shows only −1; others also +1, +3, +5, +7 (d orbitals).
- Acid strength: HF < HCl < HBr < HI; oxidising power F₂ > Cl₂ > Br₂ > I₂.
- Bond energy: Cl₂ > Br₂ > F₂ > I₂ (F–F weak due to lone-pair repulsion).
- Interhalogens (ClF₃, IF₇); XeF₂ linear, XeF₄ square planar, XeF₆ distorted octahedral.
6. Key Points to Remember
- Anomalous behaviour of the first member: small size, no d orbitals.
- Oxoacids of P: H₃PO₂ (monobasic), H₃PO₃ (dibasic), H₃PO₄ (tribasic).
- Bleaching by Cl₂ is by oxidation (permanent); by SO₂ by reduction (temporary).
- Noble gases: He in balloons, Ar in bulbs, Ne in signs.
Remember: Group trends | inert pair effect | key reactions (Ostwald, Contact) | Xe fluorides
The p-Block Elements: questions and notes
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- Solutions
- Electrochemistry
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- The p-Block Elements
- The d- and f-Block Elements
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