MCQ Detailed View

The water molecule (H₂O) consists of a central oxygen atom bonded to two hydrogen atoms. Its molecular geometry can be explained using VSEPR (Valence Shell Electron Pair Repulsion) theory, which predicts the arrangement of atoms based on electron pair repulsion.

Oxygen has two bonding pairs and two lone pairs of electrons. According to VSEPR theory, the four pairs of electrons around oxygen adopt a tetrahedral electron geometry to minimize repulsion. However, the two lone pairs occupy more space than the bonding pairs, which compresses the H–O–H bond angle.

As a result, the molecular shape of H₂O is V-shaped (bent) with a bond angle of approximately 104.5°. This shape is different from a pyramidal geometry, which applies to molecules like NH₃, and from triangular planar, which applies to molecules like BF₃.

The V-shaped structure of water is responsible for many of its unique physical and chemical properties. The bent geometry creates a polar molecule with a net dipole moment, making water an excellent solvent for polar substances. It also explains properties such as hydrogen bonding, high boiling point, high surface tension, and specific heat capacity.

Understanding the V-shaped geometry of water is a fundamental concept in physical chemistry and is crucial for explaining molecular polarity, intermolecular forces, and chemical reactivity. The lone pair effect and bond angle compression are key concepts students must grasp to analyze molecular shapes and predict molecular behavior accurately.