Exercise 9.12
What kind of ion will oxygen (O) form?
NCERT’s answer
Anion (\(\displaystyle O^{2-}\))
Oxygen forms an anion — the oxide ion, \(\displaystyle O^{2-}\).
Oxygen (\(\displaystyle Z = 8\)) has the configuration $\displaystyle 2$, $\displaystyle 6$: six valence electrons, two short of an octet.
An atom with more than $\displaystyle 4$ valence electrons gains electrons rather than losing them, so oxygen accepts $\displaystyle 2$.
It then has $\displaystyle 8$ protons but $\displaystyle 10$ electrons, a net charge of $\displaystyle 2$−, and the stable arrangement $\displaystyle 2$, 8.