Oxygen, sulfur and selenium are all nonmetals, while our metalloids are polonium and talorium. Now notice, unlike group five A and four A, which both have metals, group six A, or the calcigens, don't have any metals. Now, let's begin with oxygen. Now, in this lecture, we're only really going to look at oxygen and sulfur because they occur way more frequently than any of these three guys. So let's look at oxygen. Oxygen is the second most electronegative atom.