So here we're taking an overall look at the different types of isomers that exist. Remember, structural isomers have the same molecular formula but different connectivity. In both of these images, we have C4H10, 4 carbons, 10 hydrogens. The one on the left has them all oriented in a chain, but the one on the right has 3 of them in a chain, and one branching group. So they're connected differently, but they still have the same molecular formula of C4H10. On the other side, we're looking at stereo isomers, which we just learned can be further divided into geometric and optical isomers. Here in the geometric one, we're able to tell that they're geometric isomers by the inclusion of a double bond. Now if we're looking at the double bond, we see we have these 2 CH3 groups on the same side with each other. And then here we have them on opposite sides of each other. Later on, we'll learn that when they're on the same side, these two groups, they are cis. And then when we have 2 groups opposite each other, they're called trans.
Optical isomers, the way we are able to tell we have optical isomers is just imagine you're looking into a mirror. Looking into a mirror, we'd see the inversion of ourselves. But another way we can show that we have an optical isomer, is we look at the bonds that show spatial orientation. Instead of looking into a mirror, if we looked into a mirror what we would see would be the same molecule. This is looking into a mirror, so OH would be over here, and then this H would be back here, and this C H3 would be here. That would be our mirror image. Sometimes it's hard to depict that because you're moving things and orienting them in a different way. An easier approach would just be to look at the bonds that have spatial orientation, and invert them. So here, this is a dashed, wedged bond, we change it to a solid wedged bond. This is a solid wedged bond, we change it to a dashed wedged bond. Doing it this way by inverting the bonds that show actual spatial orientation, and holding everything else in the same position, this actually becomes its optical isomer. This is its mirror image. Okay? So again, you can look into a mirror and actually draw this, which is a bit trickier, or you can just invert the bonds that are solid or dashed. Right? So these are the different types of isomers that exist. Remember isomers here have the same molecular formula, but they may have the same connectivity or spatial orientation, or different connectivity and spatial orientation. Depending on what happens, you can fit under structural isomers or stereo isomers.
