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🧪 Chemistry  ·  Chemical Bonding and Molecular Structure  ·  NEET & JEE

Why is the bond angle in water (104.5°) less than in NH<sub>3</sub> (107°)?

Answer: Water has two lone pairs vs one in NH 3 ; greater lone pair repulsion compresses the angle more in water.

  • A Water has two lone pairs vs one in NH<sub>3</sub>; greater lone pair repulsion compresses the angle more in water
  • B Nitrogen in NH<sub>3</sub> carries a noticeably larger atomic radius than oxygen does in water in general practice
  • C Water's O-H bonds are generally shorter in length than NH<sub>3</sub>'s N-H bonds as frequently described in most textbook accounts
  • D Water possesses a greater overall molecular polarity than ammonia does during normal conditions as generally observed

Correct answer: A. Water has two lone pairs vs one in NH<sub>3</sub>; greater lone pair repulsion compresses the angle more in water

Explanation: Two lone pairs in H<sub>2</sub>O cause greater repulsion than one lone pair in NH<sub>3</sub>, reducing the bond angle further from tetrahedral.

Linear180 deg, e.g. CO2Trigonal Planar120 deg, e.g. BF3Tetrahedral109.5 deg, e.g. CH4Trigonal Bipyramidale.g. PCl5Octahedrale.g. SF6

VSEPR theory predicts molecular shape from the number of bonding and lone electron pairs around the central atom.

Concept context

Understand how atoms join to form molecules. Covers ionic and covalent bonding, VSEPR theory, hybridization (sp, sp², sp³), molecular orbital theory, bond polarity, and intermolecular forces like hydrogen bonding.

Read the full Chemical Bonding and Molecular Structure notes →