The Cheat Sheet Dashboard
Scan these golden rules first — they answer most multiple-choice traps.
Group 13 — Boron Family
B, Al, Ga, In, Tl · outer config ns² np¹ · common oxidation state +3.
Heavier elements (In, Tl) prefer the +1 state — inert pair effect. B is a non-metal (covalent); the rest are metals.
Group 14 — Carbon Family
C, Si, Ge, Sn, Pb · outer config ns² np² · common oxidation state +4; heavier prefer +2.
Catenation order: C ≫ Si > Ge ≈ Sn ≫ Pb. C–C bonds form long chains; Pb²⁺ dominant due to inert pair.
Anomalous Behaviour (B & C)
The first member of each group stands apart — small size, high IE/EN, and no d-orbitals.
So B can't expand octet (max BF₄⁻, no BF₆³⁻); C forms strong p–p multiple bonds (CO₂, alkenes/alkynes) — Si prefers single bonds and gives 3-D SiO₂.
Inert Pair Effect
Down a group, the outer ns² electrons increasingly stay put (poor shielding by d/f electrons → high penetration).
⇒ Heavier elements show a stable oxidation state 2 less than the group state: Tl⁺ and Pb²⁺ are the most stable. Pb⁴⁺ is a strong oxidiser; Sn²⁺ is a strong reducer.
Diagonal Relationship
Li↔Mg, Be↔Al, B↔Si — similar size & polarising power across a diagonal.
So B (Group 13) and Si (Group 14) both form covalent polymeric oxides, weak acidic oxides, and stable hydrides — not behaviour you'd expect from groupmates alone.
Interactive Periodic Trends
Pick a property and a group, then watch how it changes as you walk down the column. You'll see clean trends — and the funny "kinks" examiners love to test (e.g. Al < B in IE, but Ga > Al because of poor d-shielding).
Inert-Pair Effect Explorer
Pick an element from Group 13 or 14 — the explorer tells you its most stable oxidation state, why, and the practical NEET consequence (Pb⁴⁺ oxidises, Sn²⁺ reduces, etc.).
Mentor's Tip — Inert Pair Rule
Before guessing the oxidation state of a heavy p-block element, ask: "Am I above or below the diagonal?" Light elements stick to the group state; heavy elements drop by 2 thanks to the inert pair effect.
- Group 13 default: +3 for B, Al, Ga — but +1 for Tl (Tl³⁺ is a strong oxidiser, TlCl₃ < TlCl in stability).
- Group 14 default: +4 for C, Si, Ge — but +2 for Pb. Sn shows both (Sn²⁺ is a reducer, Sn⁴⁺ stable).
- The trap: Pb⁴⁺ compounds (PbO₂, PbCl₄) are oxidising agents; Sn²⁺ compounds (SnCl₂) are reducing agents. Memorise this pair!
- Why? Going down, the ns² pair is held tighter (poor d/f shielding), so it doesn't take part in bonding.
Quick Reactions & Key Compounds
The handful of reactions and structures that account for most NEET questions on this chapter. Memorise the right-hand side.
Must-Memorise — for Aamirah
1Group Configurations & Character
- Group 13 (B, Al, Ga, In, Tl): ns² np¹ · common +3 · B is non-metal, rest metals; Tl⁺ most stable.
- Group 14 (C, Si, Ge, Sn, Pb): ns² np² · common +4 · C non-metal, Si/Ge metalloids, Sn/Pb metals; Pb²⁺ most stable.
- Metallic character increases down both groups.
2Trend Orders (memorise verbatim)
- 1st IE — Group 13: B > Tl > Ga > Al > In (not monotonic!)
- Atomic radius — Group 13: Tl > In > Al > Ga > B (Ga < Al kink)
- Atomic radius — Group 14: Pb > Sn > Ge > Si > C
- 1st IE — Group 14: C > Si > Ge > Pb > Sn (Pb > Sn due to f-shielding)
- Electronegativity (Group 14): C ≫ Si ≈ Ge ≈ Sn < Pb (C highest by far)
3Acidity Orders
- Lewis acidity of BX₃: BF₃ < BCl₃ < BBr₃ < BI₃ (back-bonding from F weakens BF₃).
- Group 13 oxides: B₂O₃ acidic → Al₂O₃, Ga₂O₃ amphoteric → In₂O₃, Tl₂O₃ basic.
- Group 14 oxides: CO₂, SiO₂ acidic · GeO₂ weakly acidic · SnO, PbO amphoteric · SnO₂, PbO₂ amphoteric.
- Boric acid H₃BO₃ is a monobasic Lewis acid (accepts OH⁻, doesn’t donate H⁺).
4Catenation & Bond Strengths
- Catenation: C ≫ Si > Ge ≈ Sn ≫ Pb.
5Hybridisation Cheat-Sheet
6Key Compounds & Their Formulas
Na₂B₄O₇·10H₂OH₃BO₃ or B(OH)₃B₂H₆B₃N₃H₆SiCSiO₂CO + N₂CO + H₂Pb₃O₄2PbCO₃·Pb(OH)₂7Inert-Pair Trio (oxidiser vs reducer)
- Oxidising agents: Tl³⁺, Pb⁴⁺ (PbO₂, PbCl₄, Pb₃O₄) — they want to drop back to Tl⁺ / Pb²⁺.
- Reducing agents: Sn²⁺ (SnCl₂), Ga⁺ — they want to climb to Sn⁴⁺ / Ga³⁺.
- Most stable +1 in Group 13 → Tl⁺. Most stable +2 in Group 14 → Pb²⁺.
- Order of inert-pair effect: C < Si < Ge < Sn < Pb.
- Thermal stability: PbCl₂ > PbBr₂ > PbI₂; PbCl₂ > PbCl₄.
8Anomalies & “Doesn’t Exist”
- BF₆³⁻ does NOT exist — B has no d-orbitals (max coord. = 4).
- SiF₆²⁻ exists; CF₆²⁻ does NOT (Si has 3d-orbitals).
- CO₂ is a gas; SiO₂ is a 3-D solid (no p–π in Si).
- B³⁺ cation does NOT exist — B forms covalent bonds (high IE, small size).
- Only C in Group 14 forms p–p multiple bonds readily (C=C, C≡C, C=O).
- Anhydrous AlCl₃ exists as Al₂Cl₆ dimer (in water, as [Al(H₂O)₆]³⁺).
- HF attacks glass: SiO₂ + 4HF → SiF₄ + 2H₂O.
- Boric acid is monobasic and Lewis, not Brønsted.
9Numbers Worth Memorising
10Reactions to Recall in One Line
- BF₃ + 3H₂O → H₃BO₃ + 3HF (hydrolysis)
- B₂H₆ + 6H₂O → 2H₃BO₃ + 6H₂
- 3B₂H₆ + 6NH₃ → 2B₃N₃H₆ + 12H₂ (borazine)
- Al + NaOH + H₂O → NaAlO₂ + H₂↑ (amphoteric Al)
- 2Al + 6HCl → 2AlCl₃ + 3H₂↑
- SiO₂ + 4HF → SiF₄ + 2H₂O
- Si + 2NaOH + H₂O → Na₂SiO₃ + 2H₂
- n Me₂SiCl₂ + n H₂O → (Me₂SiO)n + 2n HCl (silicone)
- SnCl₂ + 2HgCl₂ → SnCl₄ + Hg₂Cl₂ (Sn²⁺ reducer)
Quick-Recall Flashcards
Tap a card to flip and reveal the high-yield fact.
Easy Explanation — Line by Line
Each key idea of the chapter in plain words, with 5 possible NEET questions for each. Tap "Show answer" on any one.
Exceptions to Remember
Examples & Reference Data
| Element / Compound | Significance / Use |
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Solved Problems — Explained & Worked
Representative numericals/conceptuals on each topic, with an easy explanation and a step-by-step answer.