Classify each as a lewis acid or lewis base...
A)H20
B)O2-
C)Cu2+
D)SO3
E)AlCl3
Lewis acids are electron pair acceptors.
Lewis bases are electron pair donors.
Look at H2O, for example.
..
H:O:
..
H
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?)
Your classification is mostly correct.
A) H2O: You are correct, it is a Lewis base because it has a lone pair of electrons to donate.
B) O2-: You are correct, it is a Lewis base because it has two extra electrons available to donate.
C) Cu2+: This is incorrect. Cu2+ is a Lewis acid because it can accept a pair of electrons to fill its d-orbital.
D) SO3: You are correct, it is a Lewis acid because it can accept a pair of electrons to complete its octet.
E) AlCl3: You are correct, it is a Lewis acid because aluminum can accept a pair of electrons to complete its octet.
Your reasoning is correct for H2O as a Lewis base. It cannot accept any electrons since its electron pair is already involved in a covalent bond.
For the other compounds:
- O2- is indeed a Lewis base. It has excess electrons, making it capable of donating an electron pair.
- Cu2+ is a Lewis acid. It is a cation with an empty 3d orbital, which can accept a pair of electrons.
- AlCl3 is a Lewis acid. Aluminum has an incomplete octet and can accept an electron pair from a Lewis base.
- SO3 is a Lewis acid. It can accept an electron pair due to the presence of empty p orbitals on the sulfur atom.
So, in summary:
A) H2O - Lewis base (electron pair donor)
B) O2- - Lewis base (electron pair donor)
C) Cu2+ - Lewis acid (electron pair acceptor)
D) SO3 - Lewis acid (electron pair acceptor)
E) AlCl3 - Lewis acid (electron pair acceptor)