Covers NCERT Class 11 Chemistry, Chapter "Chemical Bonding and Molecular Structure" — the conceptual backbone for organic mechanism, coordination chemistry and molecular shapes across the entire NEET syllabus.
VSEPR shapes and bond angles (especially exceptions like NH₃ vs BF₃, SF₄, ClF₃), determining hybridisation from a Lewis structure, Molecular Orbital Theory bond order and magnetic behaviour (O₂, N₂, and their ions), types and relative strength of hydrogen bonding, and dipole moment comparisons across similar molecules.
Kössel–Lewis approach: atoms bond to achieve a stable noble-gas-like octet, either by complete transfer of electrons (ionic) or by sharing (covalent).
Ionic bond formation is favoured by low ionisation enthalpy of the metal, high (more negative) electron gain enthalpy of the non-metal, and high lattice enthalpy of the resulting solid.
Bond parameters: bond length decreases and bond enthalpy increases as bond order increases (single < double < triple). Bond angle is a direct clue to hybridisation and lone-pair count.
VSEPR: electron pairs (bonding + lone) around a central atom arrange to minimise repulsion, in the order lone pair–lone pair > lone pair–bond pair > bond pair–bond pair. This single ordering explains almost every "why is the bond angle less than ideal" question.
Hybridisation shortcut: count σ-bonds + lone pairs on the central atom. 2→sp, 3→sp², 4→sp³, 5→sp³d, 6→sp³d².
Molecular Orbital Theory: bond order = ½(N_bonding − N_antibonding). A molecule/ion is paramagnetic if it has unpaired electrons in its MO configuration (e.g. O₂), diamagnetic if all electrons are paired (e.g. N₂).
Hydrogen bonding needs H attached to a small, highly electronegative atom (F, O, N). Intermolecular H-bonding raises boiling point (HF, H₂O anomalies); intramolecular H-bonding (e.g. o-nitrophenol) instead lowers it compared to the para isomer.
Dipole moment (μ = q×d, in Debye) is a vector — symmetric molecules like BF₃ and CO₂ have μ = 0 despite polar bonds, because bond dipoles cancel; NH₃ retains a net dipole because its lone pair breaks that symmetry.
| Hybridisation | Shape | Ideal bond angle | Example |
|---|---|---|---|
| sp | Linear | 180° | BeCl₂, CO₂ |
| sp² | Trigonal planar | 120° | BF₃, SO₃ |
| sp³ | Tetrahedral | 109.5° | CH₄ |
| sp³ (1 lone pair) | Pyramidal | ~107° | NH₃ |
| sp³ (2 lone pairs) | Bent / V-shaped | ~104.5° | H₂O |
| sp³d | Trigonal bipyramidal | 90° & 120° | PCl₅ |
| sp³d² | Octahedral | 90° | SF₆ |
Original questions modelled on recurring NEET question types — not verbatim reproductions of any official paper.
Scaled from direct NCERT application (Q1–Q6) to mixed NEET-level difficulty (Q7–Q15).
Purely a recall device — not a reinterpretation of the source stories.
Ardhanarishvara, the composite form of Shiva and Parvati, is one whole made of two equal halves. Picture a non-polar covalent bond (like H–H or Cl–Cl) the same way: two identical atoms merging into one shared electron cloud, contributing and holding the pair with perfectly equal claim. Where the two halves differ in "strength" — one atom pulling the shared pair closer — you get a polar covalent bond instead: still shared, but no longer symmetric.
Think of a metal atom as a minor chieftain who finds one lone electron a burden to guard, and a non-metal atom as a well-fortified court that has room for exactly one more attendant to complete its guard of eight. The chieftain hands the electron over willingly — it's a transfer both sides are better off for, not a struggle. That willing, complete transfer, followed by the two now-charged ions holding together purely by electrostatic attraction, is the ionic bond: NCERT's own language of "complete transfer of an electron" mapped onto something easier to hold in memory.
"Loners push hardest" — lone pair–lone pair > lone pair–bond pair > bond pair–bond pair. Every "smaller than ideal angle" question in this chapter reduces to counting lone pairs and applying this one line.