Atomic Structure and Chemical Bonding — Question 18

(a) Elements with the valence shell having 8 electrons and helium with 2 electrons, cannot gain or lose electrons so they are chemically inactive and are called inert elements.

(b) Inert elements exist as monoatoms because they have a completely filled outermost electron shell. This makes them very stable and unlikely to form chemical bonds with other atoms. Hence, they tend to exist as monoatoms in molecules rather than participating in chemical reactions.

(c) Electrons present in the outermost shell (i.e., valence shell) of an atom are valence electrons.