BF3 is non polar but NF3 is polar why?

BF3 is non polar as it has trigonal planer shape (sp 2 hybridisation) which is symmetrical in all respects. here, the bonded electrons as you know, are situated at the verticies of an equilateral triangle. thus its resultant dipole is 0.

but, NF3 is pyramidal (hybridisation sp 3 with a lone pair) in structure.flourine being more electronegative, its resultant dipole is downwards and hance not 0.

hope you got the answer.

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