posted by Adam .
Classify each as a lewis acid or lewis base...
Lewis acids are electron pair acceptors.
Lewis bases are electron pair donors.
Look at H2O, for example.
This molecule has no "holes" to accept an electron. Would you expect this to be an acid or a base by Lewis standards?
I think it would be a base because like you said it has no space to accept any electrons. As, for the other compounds is this correct:
O2- is a lewis base
Cu2+ is a lewis base
AlCl3 is an acid
SO3 is an acid
I believe Cu^+2 is a Lewis acid (isn't it accepting electrons to make it Cu?)