Question

Water is a liquid while all other hydrides of group 16 elements are gases at room temperature. Explain.

Answer 1

1. Water (H₂O) is a liquid at room temperature, but other hydrides of group 16 elements (H₂S, H₂Se, H₂Te) are gases.
2. This is because water molecules form strong intermolecular hydrogen bonds due to the high electronegativity of oxygen.
3. Hydrogen bonding causes water molecules to stick together, increasing its boiling point and making it a liquid.
4. Other hydrides have lower electronegativity atoms (S, Se, Te), so hydrogen bonding is absent; only weak van der Waals forces exist.
5. These weak forces result in lower boiling points and a gaseous state for other hydrides at room temperature.
6. The boiling points of other hydrides increase down the group due to stronger van der Waals forces from larger molecular size.

Hence, water is a liquid due to strong hydrogen bonding; others are gases because of weak intermolecular forces.