Tue February 14, 2012 By: Sagar

If catenation decreases down a group, then why does P show maximum catenation?

Expert Reply
Wed February 15, 2012

Catenation is much more common in phosphorous compounds than in nitrogen compounds. This is because of the relative weakness of the N?N single bond as compared to the P?P single bond. Phosphorus shows maximum catenation because of most stable P-P bond. Since nitrogen atom is smaller, there is greater repulsion of electron density of two nitrogen atoms, thereby weakening the N?N single bond.  The bond dissociation energy of N-N bond is less than that of P-P bond.

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