The difference in the physical states of oxygen and water at room temperature primarily comes down to the nature of their molecular structures and the types of intermolecular forces that hold their molecules together.
Oxygen (O2) is a diatomic molecule consisting of two oxygen atoms bonded together. At room temperature, the molecular force between oxygen molecules is relatively weak. This weak van der Waals force allows oxygen to exist as a gas under normal atmospheric conditions. The molecules move freely and are spread out, which is characteristic of most gases.
On the other hand, water (H2O) exhibits strong hydrogen bonding due to the polar nature of its molecules. Each water molecule can form hydrogen bonds with up to four neighboring molecules. These intermolecular forces are significantly stronger than those in oxygen. As a result, water molecules are held close together, which allows water to remain in a liquid state at room temperature.
In summary, the key factor that differentiates oxygen from water at room temperature is the strength of the intermolecular forces at play. While oxygen’s weak interactions enable it to exist as a gas, the strong hydrogen bonds in water keep it as a liquid.