Is quantum theory the true foundation of chemistry?

[pivoxa15]

Chemistry deals with say 10^10 atoms or more (many types of molecules intermolecularly bounded together by dipole or disperson forces) so saying that quantum theory is the foundations of chemistry may be not be fully correct as quantum theory deals with countable number of atoms and only small molecules. Chemistry also grew out before the advent of quantum theory. Is it more correct to say that it is the 2nd law of thermodynamic which is at the foundations of chemistry? Chesmitry deals a lot with energy changes of molecules. i.e a molecule will change to a lower energy state. That use to puzzle me. How does a molecule 'know' there is a lower energy state in the first place? However I now realize it is really the 2nd law of thermodynamics and so the molecule doesn't 'know' but just does it 'naturally' according to this law.

 

[t!m]

quantum theory deals with countable number of atoms and only small molecules

Not true. At the present time, only relatively small molecules can be treated (almost) exactly with quantum theory, but this is only due to their computational intractability. Nonetheless, quantum mechanics is applicable to everything, it's just silly to use it to describe macroscopic objects, where Newtonian physics applies (and is much simpler). The interactions of atoms and molecules is still very much determined by quantum mechanics.