Hydrogen Bonding — Intermolecular, intramolecular
Chemical Bonding
15
JEE Qs
8%
Hard
45
min
Master the conditions for hydrogen bond formation and its distinct effects on physical properties (BP, MP, solubility) to correctly differentiate between intermolecular and intramolecular types and explain observed trends.
✅ Key Points for JEE
- 1Hydrogen bonding occurs when a hydrogen atom covalently bonded to a highly electronegative atom (F, O, or N) forms an electrostatic attraction with another highly electronegative atom (F, O, or N) in the same or a different molecule.
- 2Intermolecular hydrogen bonding (between molecules) increases boiling point, melting point, viscosity, and solubility in polar solvents (like water) by increasing the energy required to overcome intermolecular attractions.
- 3Intramolecular hydrogen bonding (within the same molecule) forms a stable ring structure (chelation) and can reduce intermolecular interactions, often leading to a decrease in boiling point and solubility compared to isomers lacking such bonding.
- 4The strength of hydrogen bonds is primarily determined by the electronegativity of the atoms involved and follows the general order: F-H···F > O-H···O > N-H···N, also influenced by the size and steric accessibility of the atoms.
- 5Anomalous physical properties of substances like water (high boiling point, density maximum at 4°C), HF (high boiling point), and alcohols are direct consequences of strong intermolecular hydrogen bonding.
⚠️ Common Mistakes
- ✕Assuming hydrogen bonding can occur with any electronegative atom (e.g., Cl, S, Br) instead of strictly F, O, N.
- ✕Confusing strong dipole-dipole interactions with hydrogen bonding, or mistakenly treating hydrogen bonding as a type of covalent bond.
- ✕Incorrectly predicting that intramolecular hydrogen bonding always leads to an increase in boiling point, when it often decreases it by hindering intermolecular interactions.
- ✕Failing to consider the steric and geometric requirements for effective hydrogen bond formation, especially in complex organic molecules.
📝 Practice Questions
See allQ75.Total number of non bonded electrons present in NO2− ion based on Lewis theory is 2025 (29 Jan Shift 2) JEE Main Previous Year Paper
Q71.The number of molecules/ions that show linear geometry among the following is ________ SO2, BeCl2, CO2, N−3 , NO2, F2O, XeF2, NO+2 , I−3 , O3
Q69.Arrange the following compounds in increasing order of their dipole moment : HBr, H2 S, NF3 and CHCl3 (1) H2 S < HBr < NF3 < CHCl3 (2) NF3 < HBr < H2 S < CHCl3 (3) HBr < H2 S < NF3 < CHCl3 (4) CHCl3 < NF3 < HBr < H2 S
Q64.Which of the following statement is true with respect to H2O, NH3 and CH4 ? A. The central atoms of all the molecules are sp3 hybridized. B. The H −O −H, H −N −H and H −C −H angles in the above molecules are 104.5∘, 107.5∘ and 109.5∘ , respectively. C. The increasing order of dipole moment is CH4 < NH3 < H2O. D. Both H2O and NH3 are Lewis acids and CH4 is a Lewis base. E. A solution of NH3 in H2O is basic. In this solution NH3 and H2O act as Lowry-Bronsted acid and base respectively. Choose the correct answer from the options given below: (1) A, B and C Only (2) A, D and E Only (3) C, D and E Only (4) A, B, C and E Only
Q70.Which of the following linear combination of atomic orbitals will lead to formation of molecular orbitals in homonuclear diatomic molecules [internuclear axis in z -direction] ? A. 2pz and 2px B. 2 s and 2px C. 3 dxy 2025 (24 Jan Shift 1) JEE Main Previous Year Paper and 3 dx2−y2 D. 2 s and 2pz E. 2pz and 3dx2 −y2 Choose the correct answer from the options given below: (1) A and B Only (2) D Only (3) E Only (4) C and D Only
Q53.Given below are two statements : Statement (I): Experimentally determined oxygen-oxygen bond lengths in the O3 are found to be same and the bond length is greater than that of a O = O (double bond) but less than 2025 (24 Jan Shift 2) JEE Main Previous Year Paper that of a single (O −O) bond. Statement (II) : The strong lone pair-lone pair repulsion between oxygen atoms is solely responsible for the fact that the bond length in ozone is smaller than that of a double bond (O = O) but more than that of a single bond (O −O). In the light of the above statements, choose the correct answer from the options given below : (1) Both Statement I and Statement II are false (2) Statement I is false but Statement II is true (3) Statement I is true but Statement II is false (4) Both Statement I and Statement II are true
NCERT Chapters
- Class 11 Chemistry Ch 4: Chemical Bonding and Molecular Structure
- Class 11 Chemistry Ch 5: States of Matter
- Class 12 Chemistry Ch 11: Alcohols, Phenols and Ethers
- Class 12 Chemistry Ch 13: Amines