🧪Chemistry

Chemical Bonding

Ionic, covalent, metallic bonds, VSEPR theory, hybridisation, MO theory, and hydrogen bonding.

Class 11Class 12

What You Will Learn in Chemical Bonding

Chemical bonding is the force of attraction that holds atoms together in a molecule or compound, arising from redistribution of electrons.

Ionic bond: complete electron transfer from metal to non-metal (e.g., NaCl). High mp/bp, conducts when molten/dissolved.
Covalent bond: electron sharing between non-metals (e.g., H₂O, CO₂). Can be polar or non-polar.
VSEPR theory: electron pairs repel — lone pair > bond pair; determines molecular geometry.
Hybridisation: sp (linear, 180°), sp² (trigonal planar, 120°), sp³ (tetrahedral, 109.5°).
Hydrogen bond: weak electrostatic attraction between H (bonded to N/O/F) and electronegative atom.
Fajan's rules: higher charge density → more covalent character in ionic compounds.

Key Formula

Bond order = (Bonding electrons - Antibonding electrons) / 2. VSEPR: AXₙEₘ (A=central, X=bond, E=lone pair).

Example

Water (H₂O) has sp³ hybridisation with 2 lone pairs giving a bent shape (104.5°).

Solved Numerical Example

Calculate bond order of O₂ using MO theory.
Molecular orbital config of O₂: σ1s² σ*1s² σ2s² σ*2s² σ2p² π2p⁴ π*2p².
Bonding e⁻ = 8, Antibonding e⁻ = 4. Bond order = (8-4)/2 = 2. O₂ has a double bond and 2 unpaired electrons (paramagnetic).

Expected Exam Questions — Chemical Bonding

Q1.Explain the VSEPR theory. Predict the shape of NH₃ and H₂O.

Answer: VSEPR: electron pairs (bonding + lone) around central atom arrange to minimise repulsion. NH₃: AX₃E₁ — 3 bonding, 1 lone pair → trigonal pyramidal (107°). H₂O: AX₂E₂ — 2 bonding, 2 lone pairs → bent/V-shape (104.5°). Lone pair repulsion > bond pair repulsion reduces angle.

Q2.Why is the boiling point of H₂O much higher than H₂S?

Answer: H₂O forms extensive intermolecular hydrogen bonds (O-H···O) because oxygen is highly electronegative and small. H₂S cannot form hydrogen bonds (sulphur is less electronegative, larger). Stronger intermolecular forces in H₂O require more energy to overcome → higher bp (100°C vs -60°C).

Q3.What is the hybridisation of carbon in CH₄, C₂H₄, and C₂H₂?

Answer: CH₄: sp³ (4 single bonds, tetrahedral). C₂H₄: sp² (double bond = 1σ + 1π, trigonal planar). C₂H₂: sp (triple bond = 1σ + 2π, linear). Formula: hybridisation = ½(valence e⁻ + bonds - charge).

🔘 MCQ Practice — Chemical Bonding

MCQ 1.Which of the following has a tetrahedral geometry?

A. BF₃

B. NH₃

C. CH₄ ✓

D. H₂O

✓ Correct Answer: CH₄

MCQ 2.The type of bond present in NaCl is:

A. Covalent

B. Metallic

C. Ionic ✓

D. Hydrogen bond

✓ Correct Answer: Ionic

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Frequently Asked Questions — Chemical Bonding

What is Chemical Bonding in Chemistry?

Chemical bonding is the force of attraction that holds atoms together in a molecule or compound, arising from redistribution of electrons.

Explain the VSEPR theory. Predict the shape of NH₃ and H₂O.

VSEPR: electron pairs (bonding + lone) around central atom arrange to minimise repulsion. NH₃: AX₃E₁ — 3 bonding, 1 lone pair → trigonal pyramidal (107°). H₂O: AX₂E₂ — 2 bonding, 2 lone pairs → bent/V-shape (104.5°). Lone pair repulsion > bond pair repulsion reduces angle.

Why is the boiling point of H₂O much higher than H₂S?

H₂O forms extensive intermolecular hydrogen bonds (O-H···O) because oxygen is highly electronegative and small. H₂S cannot form hydrogen bonds (sulphur is less electronegative, larger). Stronger intermolecular forces in H₂O require more energy to overcome → higher bp (100°C vs -60°C).

What is the hybridisation of carbon in CH₄, C₂H₄, and C₂H₂?

CH₄: sp³ (4 single bonds, tetrahedral). C₂H₄: sp² (double bond = 1σ + 1π, trigonal planar). C₂H₂: sp (triple bond = 1σ + 2π, linear). Formula: hybridisation = ½(valence e⁻ + bonds - charge).

How do I prepare Chemical Bonding for exams?

To master Chemical Bonding, start by reading the theory carefully, then go through solved examples step by step. Practice numericals (if applicable), revise key formulas, and attempt previous year questions. SII notes cover all these aspects in a structured manner.

Are these Chemical Bonding notes free?

Yes! SII provides free access to Chemical Bonding notes and introductory study materials. Enrolled students get full access to detailed notes, solved papers, and live doubt-clearing sessions.

Which exams ask questions from Chemical Bonding?

Chemical Bonding is an important topic tested in Class 11, Class 12 board exams, as well as JEE Main, JEE Advanced, NEET. It frequently appears in both short-answer and long-answer sections.