Answering Exam Questions

Question 1

Inert Pair effect

Answer 1

Tendancy of the 2 electrons in the outer most s atomic orbital to remain unionized or unshared of post-transition metals.

Highest s electrons held in tightly which means harder for this ionization to happen and therefore Ti exists as Ti(I) and not Ti(III).

Al exists as Al(III) as it finds it easier to remove its 3s electrons.

Question 2

Irving williams series

Answer 2

1) finding the effect of varying M(II) on stability of complex
2) equilibrium: [M(OH2)6]2+ + en equib [M(OH2)4(en)]2+ + 2H2O
3) equilibrium constant to be big, product must be more abundant, therefore more stable.
4) stability generally inc. ion gets smaller, zeff increases and pulls ligands closer. More stability. Superimposed: CFSE values
5) Cu sudden jump due to jahn teller distortion

Question 3

Explain the Chelate Effect

Answer 3

Formation constant always higher for chelate complexes.

1) Statistical effect: Once chelate ligand attaches other is near by
2) delta S increases therefore delta G decreases therefore more feasible
3) hydration energy increases (delta H) which inc delta G. NH3 can H bond more than en therefore NH3 more hydration energy.
4) NH3 more repulsion for ligands when attacking metal ligand. Repulsion in (en) removed upon synthesising (en).