P Block Elements Group 13 Question 6
Question 6 - 31 January - Shift 2
The Lewis acid character of boron tri halides follows the order :
(1) $BBr_3>BI_3>BCI_3>BF_3$
(2) $BCl_3>BF_3>BBr_3>BI_3$
(3) $BF_3>BCl_3>BBr_3>BI_3$
(4) $BI_3>BBr_3>BCl_3>BF_3$
Show Answer
Answer: (4)
Solution:
Formula: Back Bonding
Extent of back bonding, reduces down the group leading to more Lewis acidic strength
$BF_3>BCl_3>BBr_3>BI_3$ (extent of back bonding)
$(2 p-2 p)(2 p-3 p)(2 p-4 p)(2 p-5 p)$
$BF_3<BCl_3<BBr_3<BI_3$ (lewis acidic nature)
