Why are noble gases monoatomic?
Due to its high stability, the noble gas atoms do not combine with other atoms. Hence, they do not form bonds with any other atoms and stay free. Therefore, they are always monoatomic.
Is sodium monoatomic ? How ? I think only noble gases are monoatomic ?
Why are noble gases sometimes called rare gases?
Being monoatomic, the atomic radius of noble gases are very small compared to covalent radius of other elements.