Q.Why do the noble gases (Group 18) generally show a valency of zero?

Step 1. Valency measures how many electrons an atom typically gains, loses or shares to reach a stable, completed valence shell.

Step 2. Group 18 elements already have a completely filled valence shell in their neutral, ground-state form — 8 electrons (an octet) for all noble gases except helium, which has 2 (a duplet).

Step 3. With no unfilled orbital to complete and no obvious energetic benefit to disturbing an already-stable shell, these elements have essentially no tendency to combine with others under ordinary conditions. …

Connect valency's definition (electrons needed to complete the valence shell) to the …

• Stating noble gases 'never' form compounds, ignoring the known xenon and krypton compounds that m …