Let’s look at the Molecular Geometry and bond angles for CO2. The first thing we need is a good Lewis structure for CO2. Right away, we can see we have 2 Oxygens that are bonded to Carbon, a central Carbon with double bonds; and that there’s nothing else attached to that Carbon–no other atoms or lone pair electrons. Since the Oxygens are the only things attached, we know according to valence shell electron pair repulsion theory, that the valence shell electrons on the Oxygens, they’re going to repel each other. So those two Oxygen atoms are going to push as far away as they can to either side of that central Carbon.
That makes this a linear molecule. We can also use the AXN notation to determine the Molecular Geometry for CO2. A, that’s the Carbon, there’s only one of those, we’ll leave that as A; X, that’s the number of atoms bonded to that central Carbon, we have 2 Oxygen atoms, so we’ll put a 2 right there; and then N, that’s the number of nonbonding electron pairs.
Here the electron pairs are all involved in chemical bonds, so there are no nonbonding or lone pair electrons. So we won’t even worry about N.
When we refer to the table, if we look for the AX2, we can see that AX2 is linear. That’s what we predicted with the valence shell electron pair repulsion theory. We can see that the bond angle, that’s 180. That’s this line straight through the molecule. Finally, you can see the molecule, the CO2 Molecular Geometry here, as the molecule rotates at the bottom of the screen.
This is Dr. B., and thanks for reading..