Question

How would you account for the following: Phosphorus shows a greater tendency for catenation than nitrogen.

Answer 1

Catenation is the property of atoms or elements to bind with the same kind of atom and form a long series of atoms or the chain. This chain can be open or in ring form. This tendency is found more peculiar in relatively larger atoms than smaller atoms. Comparatively, nitrogen is smaller than phosphorus.

Complete answer:
Catenation is the property of the formation of the single bond between the same atom to form a long chain structure. The higher stability of the single bond between the same atoms will have more affinity to undergo catenation.
The comparative size of nitrogen and phosphorus indicates that the size of nitrogen is smaller than that of phosphorus. This causes the weakness in the N-N bond as there is more repulsion of electron density due to smaller atomic size. While in the case of phosphorus, the bond is relatively stronger as the repulsion due to electron density is lower than nitrogen. Thus this causes phosphorus to have a higher tendency of catenation than nitrogen. Also as the P-P bond is stronger than the N-N bond, the enthalpy of the P-P bond is higher.
Hence, we can say that due to relatively larger atomic size, higher bond enthalpy, and lower repulsion due to electron density, phosphorus shows a greater tendency for catenation than nitrogen.

Note:
Catenation occurs more readily in carbon, and that’s the reason we can observe a very large number of hydrocarbon chains in nature. Other than carbon, a prominent catenation tendency is observed in hydrogen, silicon, sulfur, phosphorus, and some other semi metallic elements.