Question

Mention the important physical characteristics of noble gases.

Answer 1

1. Physical state: All noble gases are colourless, odourless, and tasteless. They are monoatomic in nature. Noble gases have C_p/C_v values near 1.66, indicating they are monoatomic.
2. Atomic radius: Noble gases have van der Waals’ atomic radii, which are larger than those of halogens in group 17. Atomic radius increases as one moves down the group, from He to Xe.
3. Melting and boiling points: Noble gases have lower melting and boiling points than other substances with comparable molecular masses. Moving down the group results in regular increases in melting and boiling points.
4. Ionisation enthalpy: Noble gases have high values of ionisation enthalpy. Noble gas atoms have the maximum ionisation enthalpy during their respective periods. The ionisation enthalpy reduces as one moves down the group.
5. Electron gain enthalpy: These gases do not have a tendency to receive electrons because of their stable electronic structures. They have high positive values of electron gain enthalpy as a result.
6. Solubility in water: Water lightly dissolves noble gases. The least soluble is helium. As one moves down the group, from He to Xe, the solubility of noble gases in water increases.
7. Liquefaction tendency: Noble gases are not easily liquefied. However, the tendency for liquefaction increases on moving down the group.