NEET Chemistry — Chemical Bonding Complete Chapter Guide

Chapter Overview & Weightage

Chemical Bonding is the highest-weightage chapter in NEET Chemistry from the physical/inorganic section. VSEPR theory, hybridization, and molecular orbital theory form the core. If you understand WHY bonds form, the rest follows naturally.

Chemical Bonding carries 5-6% weightage in NEET with 3-4 questions. VSEPR theory (predicting shapes) and hybridization are tested almost every year.

Year	NEET Q Count	Key Topics Tested
2025	3	Hybridization, VSEPR shapes
2024	3	MOT bond order, dipole moment
2023	4	VSEPR, hydrogen bonding, lattice energy
2022	3	Hybridization, resonance, Fajan’s rule
2021	3	Bond order, shapes, ionic character

graph TD
    A[Chemical Bonding] --> B[Ionic Bond]
    A --> C[Covalent Bond]
    A --> D[Metallic Bond]
    C --> E[VSEPR Theory]
    C --> F[Hybridization]
    C --> G[MOT]
    E --> H[Shapes: Linear to Octahedral]
    F --> I[sp, sp2, sp3, sp3d, sp3d2]
    G --> J[Bond Order]
    G --> K[Magnetic Nature]
    B --> L[Fajan's Rules]
    C --> M[Dipole Moment]

Key Concepts You Must Know

Tier 1 (Always asked)

VSEPR theory — predicting shapes from electron pairs
Hybridization of central atom in common molecules
MOT: bond order = (bonding - antibonding)/2
Dipole moment and molecular symmetry

Tier 2 (Frequently asked)

Fajan’s rules (ionic vs covalent character)
Hydrogen bonding (inter vs intramolecular)
Resonance structures and formal charge
Born-Haber cycle (lattice energy)

Tier 3 (Occasional)

Back bonding (BF $_3$ , N(SiH $_3$ ) $_3$ )
Banana bonds (B $_2$ H $_6$ )
MOT of heteronuclear diatomics

Important Formulas

Electron Pairs (BP + LP)	Shape	Example
2 + 0	Linear	BeCl $_2$
3 + 0	Trigonal planar	BF $_3$
3 + 1	Pyramidal	NH $_3$
2 + 2	Bent/V-shape	H $_2$ O
4 + 0	Tetrahedral	CH $_4$
5 + 0	Trigonal bipyramidal	PCl $_5$
4 + 1	See-saw	SF $_4$
4 + 2	Square planar	XeF $_4$
6 + 0	Octahedral	SF $_6$

Lone pairs occupy equatorial positions in TBP geometry. They compress bond angles.

\text{Bond Order} = \frac{N_b - N_a}{2}

For O $_2$ : Bond order = $(10 - 6)/2 = 2$ , paramagnetic (2 unpaired electrons in $\pi^*$ )

For N $_2$ : Bond order = $(10 - 4)/2 = 3$ , diamagnetic

For hybridization, count the steric number (bonded atoms + lone pairs on central atom). Steric number 2 = sp, 3 = sp $^2$ , 4 = sp $^3$ , 5 = sp $^3$ d, 6 = sp $^3$ d $^2$ . This shortcut works for 95% of NEET questions.

Solved Previous Year Questions

PYQ 1 — NEET 2024

Problem: The correct order of bond order is: (a) O $_2^- >$ O $_2 >$ O $_2^+$ (b) O $_2^+ >$ O $_2 >$ O $_2^-$ (c) O $_2 >$ O $_2^+ >$ O $_2^-$ (d) O $_2^- >$ O $_2^+ >$ O $_2$

Solution:

O $_2$ : BO = (10-6)/2 = 2 O $_2^+$ : Remove one antibonding electron. BO = (10-5)/2 = 2.5 O $_2^-$ : Add one antibonding electron. BO = (10-7)/2 = 1.5

Order: O $_2^+ >$ O $_2 >$ O $_2^-$ . Answer: (b)

PYQ 2 — NEET 2023

Problem: Among H $_2$ O, NH $_3$ , and CH $_4$ , the correct order of bond angle is:

Solution:

All have 4 electron pairs around the central atom (sp $^3$ hybridized), but lone pairs compress bond angles:

CH $_4$ (0 LP): 109.5 degrees NH $_3$ (1 LP): 107 degrees H $_2$ O (2 LP): 104.5 degrees

Order: CH $_4$ > NH $_3$ > H $_2$ O

Students remember that lone pairs reduce bond angles, but forget WHY. Lone pairs are closer to the central atom and occupy more space than bonding pairs. Each lone pair compresses the bond angle by roughly 2-2.5 degrees.

Difficulty Distribution

Difficulty	% of Questions	What to Expect
Easy	35%	Hybridization identification, shape naming
Medium	50%	Bond order calculation, dipole moment reasoning
Hard	15%	MOT of unusual species, back bonding, Fajan’s rules

Expert Strategy

Week 1: Master VSEPR shapes for all steric numbers (2 through 6) including lone pair effects. Make a table and memorise it — this is pure recall and scores direct marks.

Week 2: MOT for homonuclear diatomics. The filling order differs for molecules with $Z \leq 7$ (N $_2$ and lighter) vs $Z \geq 8$ (O $_2$ and heavier). Know both configurations.

Week 3: Fajan’s rules, hydrogen bonding, and dipole moment. These are conceptual and need practice with specific examples rather than formula memorisation.

A molecule can have polar bonds but zero dipole moment if the geometry is symmetric. Examples: CO $_2$ (linear), BF $_3$ (trigonal planar), CCl $_4$ (tetrahedral), XeF $_4$ (square planar). This is a NEET favourite.

Common Traps

Trap 1 — O $_2$ is paramagnetic. MOT correctly predicts that O $_2$ has 2 unpaired electrons. Lewis structure incorrectly shows all electrons paired. This is a classic “why MOT is superior” question in NEET.

Trap 2 — XeF $_2$ is linear, not bent. XeF $_2$ has 3 lone pairs and 2 bond pairs (sp $^3$ d). The lone pairs occupy equatorial positions, making the molecular shape linear. Students who count only bond pairs get the shape wrong.

Trap 3 — Hybridization does not always equal bond angle. PCl $_5$ is sp $^3$ d hybridized but has TWO different bond angles (90 degrees and 120 degrees) because axial and equatorial positions are not equivalent.

Trap 4 — Ionic character increases with electronegativity difference — but not always. Fajan’s rules show that even compounds with large EN differences can have significant covalent character if the cation is small and highly charged (like Al $^{3+}$ , Be $^{2+}$ ).