Hey, everyone. So here it says, name the following saturated heterocycle. Remember when we're numbering this heterocycle, we start out with the heteroatom. Since there's only one, we're going to start out with the sulfur atom. So this would be 1.

We then number the ring towards the next substituent. We're going to say 1, 2, 3. Our substituent is an ethyl group. So we're going to say here it's on carbon number 3. So this will be 3-ethyl.

Now remember, if our heteroatom is a sulfur, that means that the prefix will be thia. And then it's a 5-membered ring, and we know with a 5-membered ring, it would be a cyclopentane. So with this heterocycle, we say that the name is 3-ethylthiacyclopentane.