What causes CO2 to have a 180 degree angle?

A2A. Anonymous' answer is a good explanation. When I was learning about hybridization and molecule shape, though, the sp, sp2, sp3 hybridization did not immediately form a mental image of what was going on with the molecule and its shape. read more

In CO2, the carbon atom is sp hybridised, so we expect a bond angle of 180 degrees. We have 2 hybridised orbitals and 2 oxygen atoms, leaving no lone pair of electrons. So, the sp hybridisation plus non-availability of lone pair(which prevents the repulsion) causes the molecule to have a bond angle of 180 degrees as expected. read more

It's hard to believe CO2 is exactly 180 degrees unless there were some symmetry, but the same symmetry argument should apply to H2O then. read more