Boron trihalides () are notable for their Lewis acidity and susceptibility to hydrolysis. Which of t — p Block Elements Chemistry Question

💡 Solution & Explanation

Boron trihalides are Lewis acids because of their vacant $p$ -orbital. Back bonding ($p\pi-p\pi$) is *strongest* in $BF_3$ due to ideal orbital size matching ($2p-2p$), which greatly reduces its electron deficiency. Hence, Lewis acidity increases from F to I as back bonding becomes less effective. Hydrolysis of $BCl_3$ gives $H_3BO_3$ and $HCl$.