Question

Which of the following has pseudo inert gas configuration?

• A. ${\mathrm{K}}^{+}$
• B. ${\mathrm{S}}^{2-}$
• C. ${\mathrm{Cu}}^{+}$
• D. ${\mathrm{Na}}^{+}$

Answer 1

The correct option is C

${\mathrm{Cu}}^{+}$

The explanation for the correct option:-

c) ${\mathrm{Cu}}^{+}$

• If an element has $18$ electrons instead of eight electrons in its outermost shell after losing or gaining electrons, then that element has a pseudo inert gas configuration.
• The ion is stable as it has a complete valence shell but does not have the configuration of inert gas.
• Electronic configuration of $\mathrm{Cu}$:-
• $1{\mathrm{s}}^{2}2{\mathrm{s}}^{2}2{\mathrm{p}}^{6}3{\mathrm{s}}^{2}3{\mathrm{p}}^{6}3{\mathrm{d}}^{10}4{\mathrm{s}}^1$
• Electronic configuration of ${\mathrm{Cu}}^{+}$:-
• $1{\mathrm{s}}^{2}2{\mathrm{s}}^{2}2{\mathrm{p}}^{6}3{\mathrm{s}}^{2}3{\mathrm{p}}^{6}3{\mathrm{d}}^{10}$
• Therefore ${\mathrm{Cu}}^{+}$has $18$ electrons in the outermost shell after losing an electron, hence it has a pseudo inert gas configuration.

The explanation for incorrect options:-

a) ${\mathrm{K}}^{+}$

• Electronic configuration of $\mathrm{K}$
• $1{\mathrm{s}}^{2}2{\mathrm{s}}^{2}2{\mathrm{p}}^{6}3{\mathrm{s}}^{2}3{\mathrm{p}}^{6}4{\mathrm{s}}^1$
• Electronic configuration of ${\mathrm{K}}^{+}$
• $1{\mathrm{s}}^{2}2{\mathrm{s}}^{2}2{\mathrm{p}}^{6}3{\mathrm{s}}^{2}3{\mathrm{p}}^6$
• ${\mathrm{K}}^{+}$ has eight electrons in the outermost shell after losing an electron and hence it has an inert gas configuration.

b) ${\mathrm{S}}^{2-}$

• Electronic configuration of $\mathrm{S}$
• $1{\mathrm{s}}^{2}2{\mathrm{s}}^{2}2{\mathrm{p}}^{6}3{\mathrm{s}}^{2}3{\mathrm{p}}^4$
• Electronic configuration of ${\mathrm{S}}^{2-}$
• $1{\mathrm{s}}^{2}2{\mathrm{s}}^{2}2{\mathrm{p}}^{6}3{\mathrm{s}}^{2}3{\mathrm{p}}^6$
• ${\mathrm{S}}^{2-}$ has eight electrons in the outermost shell after gaining two electrons and hence it has an inert gas configuration.

d) ${\mathrm{Na}}^{+}$

• Electronic configuration of $\mathrm{Na}$
• $1{\mathrm{s}}^{2}2{\mathrm{s}}^{2}2{\mathrm{p}}^{6}3{\mathrm{s}}^1$
• Electronic configuration of ${\mathrm{Na}}^{+}$
• $1{\mathrm{s}}^{2}2{\mathrm{s}}^{2}2{\mathrm{p}}^6$
• ${\mathrm{Na}}^{+}$has eight electrons in the outermost shell after losing an electron and hence it has an inert gas configuration.

Therefore c) ${\mathrm{Cu}}^{+}$has a pseudo inert gas configuration.