Now when we talk about molecular orbital theory, we're talking about more than one atom kind of combining their electrons together. So we're going to say here, when atoms pool their electrons, the electron orbital diagrams are shown vertically. We're going to say even though they're shown vertically, we're going to use the same 3 principles to draw these vertical electron orbital diagrams.

So here it says film the electron orbital diagrams for two oxygen atoms that are combining their electrons. First of all, oxygen has an atomic number of eight oxygens. Electron configuration is 1S² 2S² 2P⁴, so we could think of this as being one oxygen atom here for this column and one oxygen atom here for this column. And all we're going to do here is we're going to fill in their electron orbital diagrams vertically.

SO 1S² means that we have one up, one down, one up, one down, 2S² one up, one down, one up, one down, and then 2P orbitals are all same energy or degenerate. So we follow Hund's rule. We need to fill in four electrons. So up, up, up come back around, down, same here, up, up, up, come back, around, down. So this is an illustration of us prepping the pooling of electrons for the two oxygen atoms.

Here we're still seeing them as two separate electron orbital diagrams. We haven't pulled them together yet. That's what's going to happen here in this space. So click on to the next video and let's see what happens when we start to pull together electrons found in atomic orbitals. Do they get a new description? What's going to happen?