Question

Which is the most ionic
(1) LiF
(2) Li2O
(3) Li3N
(4) All same
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Answer 1

Answer:

The correct option is (1) LiF

Explanation:

1. Bigger is the charge on the cation, greater will be the covalent character in the bond, according to Fajan's Rule.
2. By contrasting the electronegativity (EN) of the two elements in each compound, one can ascertain the ionic character.
3. The more electronegativity that exists between the two elements, the more ionic the property.
4. Lithium oxide and Lithium Nitride are less ionic than lithium fluoride because the Li+ cation is very small in size, which increases its polarising power and makes it easier to polarise a less electronegative element.
5. As a result, lithium oxide and lithium nitride will have a higher covalent character (than lithium fluoride), but overall, they is less ionic than lithium fluoride.
6. Also, F is the most electronegative element than oxygen and Nitrogen. So, more is the difference of Electronegativity between the cation and anion, more is the ionic character.
7. Hence, LiF is the most ionic.

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