Name: Allotropes of Sulphur
Uploaded: 2019-07-19
Duration: 6 min 39 s
Description: Sulphur is one of the most useful non-metals which has wide applications in our industries. Watch this video to learn about the important allotropes of sulphur.

Question

Why are pentahalides of

P, As, Sb

and

Bi

more covalent than their trihalides?

Accepted Answer

The oxidation state of $+ 5$ in pentahalides is more covalent as compared to the $+ 3$ oxidation state in trihalides. Due to the higher positive oxidation state of the central atom in pentahalide state, these atoms will have larger polarising power than the halogen atom attached to them since the polarising power is directly proportional to the charge.

The central atom in pentahalide state will tend to polarise more the halide ion to which it is attached. In the case of trihalides, the central atom will polarise the halogen atom to a lesser extent as compared to a pentahalide state. More is the polarisation, larger will be the covalent character of the bond. Hence, due to larger polarisation of bond in pentahalide state as compared to trihalide state, the pentahalides are more covalent than trihalides.

Why are pentahalides of $P, As, Sb$ and $Bi$ more covalent than their trihalides?

Chapter-Wise 3D Chemistry Videos from Tripura Board Chemistry 1

Allotropes of Sulphur

Oxoacids of Phosphorus

Members of Nitrogen Family

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