Question

Rank the elements Si, P, Ge and As in increasing order of their first ionization energies.

A) Si<As<P<Ge

B) Si<P<Ge<As

C) As<Ge<P<Si

D) Ge<Si<As<P

E) Ge<As<Si<P

Answer 1

The correct order is

Ge<Si<As<P (option D)

General trend - On moving downward ionisation energy decreases due to distance is increasing between nucleus and outermost electron. So, Si>Ge & P>As

On moving right to to the period ionisation energy increses because size of elements are decreasing.

So, P>Si & As>Ge

Hence we get the order

One more concept is there in nitrogen family . They have have filled p orbital which makes it more stable hance ionsiation energy automatically increase.

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