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Q.
Arrange the following in the correct order of Lewis acidity: BF3, BCl3, BBr3.
NTA AbhyasNTA Abhyas 2020Chemical Bonding and Molecular Structure
Solution:
In BF3, BCl3 and BBr3 each will shown $\text{p}_{\pi } - \text{p}_{\pi }$ back bonding as follows.
Extant of overlapping as the $2 \text{p} - 2 \text{p} > 2 \text{p} - 3 \text{p} > 2 \text{p} - 4 \text{p}$ difference between the size of p orbital increases the extent of overlapping decreases the availability of vacant orbital increases and the acidic character increases.
Hence correct order of Lewis acidity represented by option (BF3 < BCl3 < BBr3) .
