Question

Nobel gases have comparatively large atomic radius. Why?

Hint:

Van der Waals radius>Covalent radius, therefore noble gases appear to have larger atomic sizes.

Answer 1

Step 1: Nature of noble gases.
Noble gases (He, Ne, Ar, Kr, Xe, Rn) are monoatomic and chemically inert elements. They exist as isolated atoms rather than molecules.
Step 2: Mode of atomic radius measurement.
For noble gases, the atomic radius is determined as van der Waals radius, while for other elements, it is usually the covalent radius.
Step 3: Explanation.
The van der Waals radius is the distance between the nuclei of two non-bonded atoms in adjacent molecules. This distance is always larger than the covalent radius because the atoms are not bound tightly.
Step 4: Conclusion.
Hence, noble gases have comparatively large atomic radii because their atomic radius is measured as the van der Waals radius, not the covalent radius.