What is the molecular shape of H2O? A) tetrahedral B) linear C) T-shaped D) bent E) trigonal pyramidal
The Correct Answer and Explanation is:
The correct molecular shape of H2O (water) is D) bent.
Explanation:
Water (H2O) has a bent molecular geometry due to the way its atoms are arranged and the electron repulsion between the lone pairs on the oxygen atom. Here’s a detailed breakdown:
- Electron Domain and Lewis Structure:
- Oxygen has 6 valence electrons, and each hydrogen atom contributes 1 electron. The molecule forms two single bonds between oxygen and hydrogen.
- Oxygen also has two lone pairs of electrons, which occupy more space around the oxygen atom.
- VSEPR Theory (Valence Shell Electron Pair Repulsion Theory):
- According to VSEPR theory, electron pairs around an atom arrange themselves to minimize repulsion. In H2O, there are 4 electron domains around the oxygen atom: two bonding pairs (O-H bonds) and two lone pairs.
- These 4 electron pairs would ideally form a tetrahedral arrangement in space. However, because lone pairs take up more space than bonding pairs, they push the bonding pairs closer together.
- Molecular Shape:
- The result of this repulsion is that the bonding pairs of electrons are pushed into a bent shape rather than forming a linear or tetrahedral structure.
- The bond angle between the two hydrogen atoms in H2O is approximately 104.5°, which is less than the 109.5° bond angle seen in perfect tetrahedral geometry due to the presence of lone pairs.
In summary, the bent shape arises from the combination of bonding and lone pairs, creating a molecular structure where the angle between the hydrogen-oxygen-hydrogen bond is less than 109.5°, and the molecule adopts a “V”-shaped or bent geometry.
