p-Block Elements (Group 13 & 14)

Consider the following elements In, Tl, Al, Pb, Sn and Ge. The most stable oxidation states of elements with highest and lowest first ionisation enthalpies, respectively, are

1. +4 and +1
2. +4 and +3
3. +1 and +4
4. +2 and +3

Answer

(2) +4 and +3

Solution

First ionisation enthalpies ( kJ mol-1):

Group 13: Al 577, In 558, Tl 589

Group 14: Ge 762, Sn 708, Pb 715

Highest: Ge the inert pair effect is weak for Ge, so its most stable oxidation state is +4 (Ge(II) compounds are reducing).

Lowest: In its most stable oxidation state is +3 (the +1 state becomes the more stable one only at Tl).

Answer: (2)