My notes say that inert pair effect is the tendency of electron in the outermost atomic s orbital to remain unionised or unshared in compounds of post-transition metals. (Eg. Sncl2 is formed preferentially over SnCl4)
I've watched a video lecture on it from youtube but they just explained that electrons in s orbitals are ionised before d orbitals and hence the change from example +2 to +4 in Pb.
But I don't understand why s block tends to remain unionised in these post-transition metals. Could someone explain this for me?
This is for a general chemistry first year module! So I don't think the explanation is very difficult.
Thanks so much!