[oakthomas]

I'm very confused on how to interpret electron configuration of molecules. For example, how do I interpret (2a_1)^2(1b_2)^2(3a_1)^2(1b_1)^2 as water vapor? What do the subscripts and superscripts mean?
Thank you!

[mjc123]

a1, a2, b1 and b2 are symmetry labels indicating how the molecular orbitals behave under the symmetry operations of the water molecule. For example, a1 is the totally symmetric representation of the point group C_2v. If that last sentence meant nothing to you, you need to study symmetry and group theory.