Question

Which of the following isoelectronic species has lowest IE1? (A) K (B) Ca2+ (C) S2- (D) Cl-

Answer 1

Answer:

if we are starting w/ ions as indicated then note they are all isoelectronic w/ Ar - thus the one with themost protons will have greatest ionication energy

P-3 < S -2 < Cl- < K+ < Ca+2......

Answer 2

Answer:

least value is for S⁻²

Explanation:

as the isoelectric species have same no.of electrons hence the I.E mainly depends on Atomic size

more the -ve charge more is the size of the atom

and more is the positive charge less would be its size

"so it means that if u add electrons size increases and if u remove them the size would decrease"

so order of I.E in the given elements is:

Ca⁺² > K⁺ > Cl⁻ > S⁻²

hence the least value is for S⁻²

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