Question

Why does oxygen exist as a gas, whereas other elements of the group are solids at room temperature?

Answer 1

1. Oxygen exists as a diatomic molecule (O₂) due to its ability to form strong pπ-pπ double bonds between its atoms.
2. These O₂ molecules have weak van der Waals forces between them.
3. Because of these weak intermolecular forces, oxygen remains a gas at room temperature.
4. Other group 16 elements (S, Se, Te) have larger atoms and cannot form such double bonds.
5. They form larger polyatomic molecules (e.g., S₈, Se₈) linked by single bonds.
6. These larger molecules have stronger van der Waals forces, making these elements solids at room temperature.

Thus, oxygen is a gas, while other group 16 elements are solids at room temperature due to differences in molecular structure and intermolecular forces.