molecular orbital theory? my teacher was like "im not teaching it, but its going to be on your test" can you please summarize what it is,

i read the online sites,tehy don't make sense...

2 answers

What text do you have, please?
Molecular orbitals are orbitals for shared electron pairs (also called covalent bonds). They are based on Quantum Mechanics and they have been developed fully for only for diatomic molecules through the second row of the periodic table.
There are two kinds of orbitals: Bonding, and anti-bonding (marked by a star).
Starting with sigma1s^2 you place the total number of electrons for the two atoms into those orbitals until you run out of electrons. I am using the word "sigma" for the Greek (Symbol) lower case letter sigma:
sigma(1s)^2, sigma(1s)*^2, sigma(2s)^2, sigma(2s)*^2, sigma(2p)^2, π(2p)^2, π(2p)^2, π(2p)*^2, π(2p)*^2, sigma(2p)*^2.
For examples of how this orbital energy sequence is used with specific diatomic molecules of ions, go to:
http://www.mpcfaculty.net/mark_bishop/molecular_orbital_theory.htm
To find the the "bonding order", use:
[#bonding electrons - #anti-bonding] / 2
The bonding order tells you if you have a single, double, or triple covalent bond.