Question

(b) Helium is an unreactive gas and neon is a gas of extremely low reactivity. What, if anything, do their atoms have in common?

Answer 1

Element	Electronic configuration	Valence electrons	Group
$He\left(2\right)$	$2$	$2$	$18$
$Ne\left(10\right)$	$2,8$	$8$	$18$

Their outermost shells are full leading to high stability. They react only in extreme
circumstances and hence are called noble gases.