Correct Answer - Option 4 : II, III, IV
Concept:
Isoelectronic species :
- Those species having the same number of electrons but differ in nuclear charge are called isoelectronic species.
- Example: Mg2+, Na+, F–, and O2– have 10 electrons each so they are isoelectronic.
- But, their radius is different due to differences in nuclear charges.
- Ionic radius decreases along a period for Isoelectronic ions.
Isostructural species:
- The species which have different atoms or elements in them but have the same hybridization and structure are called isostructural species.
- Examples are NF3 and NH3, they have both sp3 hybridization and pyramidal shape.
Explanation:
- The species and their structures and number of electrons are given below:
Molecule |
Number of electrons |
CH3+
|
6(from C) + 3 (from H) - 1(charge) = 8 |
H3O |
8(from O) + 3(from H) - 1(positive charge) = 10
|
NH3 |
7(from N) + 3 × 1(from H) = 10
|
CH3-
|
6(from C) + 3 (from H) + 1(charge) = 10
|
- From the table above we see that CH3-, NH3, H3O+ all have 10 electrons in them.
- Hence, they are isoelectronic species.
Thus the correct option is II, III, IV.