Question

7. Explain the trend on Lewis acidity strength BF;< BC1z< BBrz<Blz and dissociation energies: B-F 649 kJ/mole, B-CI 447 kJ/mole, B-Br 372 kJ/mole, B-1 274 kJ/mole in terms of the sp² bonding model and trigonal planar geometry? 8. Which are the two common chlorides of lead? Which is more stable and why?

Answer 1

- 7 x = F, Cl, Br Iz BX spus trigonal planner. . . This type of Backbonding or resonance happens i in Bkz mo tecule. Because of the the race unt orbital on B (p orbital), which is responsible for it's acidity does not always remain vaeeunt. So, depending on the availability of the vacunt. ponbital id extent of resonance acidity differe in BX3 system. As B and if belong to : the same period so they have they highest Orbital overlap (20-20). So, it shows the least acidie behaviowi. As principle quantum no. inerieoses the overlap decreases, so, Geidity inegrease. So, Lewis acidity order is . . . BIL BBr₂ Lt BF3 LB elz <B Brz L BP3. . Also as due to this resonance, the B- bond gets partial double bond character. So, the bond energy also increases. As the be resonance is highest in B-F bond ,So, it has the righest orbital Overlap bence wighest bond energy. as overlop decreases, so if the Bond energy. So, Bond energy order BF > Belz > BBrzy Bhz 649447372274

two common chlorides of lead are abely and the bely Among these Pbele is more stable because of inert pair effect. Due to inert pair effect very high energy is required to ionised the 65t electrons. So, compared to pbely, Pbela is more stable. Pb - [xe] 4 saº - - PE) Xe 4 saº sº Prº – Txel 4 sº