Question

Which of the following ions are isoelectronic
Arrange the isoelectronic ions in decreasing order of their size.

A) Al+³B)F C)Cl^- D)O-² E)K^+ F)Mg+²


Arrange the isoelectronic ions in decreasing order of their size.​

Answer 1

Explanation:

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CHEMISTRY

K

+

,Cl

−

,Ca

2+

and S

2−

ions are isoelectronic. The decreasing order of their size is :

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ANSWER

For isoelectronic species, anions will be larger than cations.

Anions are formed when an electron is gained. As a result there is greater electron-electron repulsion and the effective nuclear charge experienced by an electron decreases. The size becomes bigger to account for these changes. Hence an electron will be larger than a neutral atom.

Similarly, cations are formed when electrons are lost. Thus there is a greater nuclear charge experienced by each electron. The electrons are pulled closer towards the nucleus. Hence the cations are smaller than the neutral atom.

For isoelectronic species,

Anion > Neutral atom > Cation.

In this case, S

2−

will be the largest and Ca

2+

will be the smallest.

The order is S

2−

>Cl

−

>K

+

>Ca

2+

.

Hence, option A is the right answer.