Question

4. which of the following is most likely to exhibit covalent bonding

a. MgCl2 b. NaCl c. OCs2 d. SO2 e. LiF

it is either c or d not sure which is most covalent

Answer 1

A covalent bond is one that forms between two non-metal atoms, and so obviously requires two non-metal atoms to be present. NaCl, MgCl₂, LiF and Cs₂O therefore do not have covalent bonds as Sodium (Na), magnesium (Mg), Cesium (Cs) and Lithium (Li) are all metals, meaning these molecules only have one non-metal atom.

Only Bigger cation (or anion) and a small anion (or cation) respectively will form a covalent bond, this is in accordance with Fajan's Rule. Fajan rules for the Polarisation:

Polarization will be increased by:
1. High charge and small size of the cation.

2. High charge and large size of the anion.

Due to higher lattice energies of Bromides and iodides they have higher stability than expected from theoretical calculations. This results in formation of a polar covalent Bond. This covalent bond is more stable than ionic bond.

Examples: aluminium iodide (AlI₃) is a covalent compound

Sulfur dioxide is purely composed of two non-metals Sulfur & Oxygen, both belongs to same group in periodic table. There is small difference between their electronegativites, we might expect this molecule will be polar, but purely covalent.

Hence SO₂ is polar covalent molecule.

Answer: d. SO₂

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