Addums become ions when they donate electrons or they gain electrons and they have an overall electric charge. Here's an example. Lithium, three protons. Electron configuration, two electrons in the inner shell, one electron in the next shell. Four diagram looks like this. So as you can see, it has one electron in its outer shell because atoms have a tendency to want a complete outer shell, this lithium atom has a tendency to want to donate this electron in its outer shell. So it removes that shell and it's got a full outer shell here. So it donates this electron to another atom under certain conditions. So then it only has two electrons left. So two negative charges and but it's got three protons. So it's got three positive charges. So overall there's one more positive than there is negative. So it's got an overall charge of one plus. I'm going to express that like this. Lithium ion is Li1 plus or we can just say Li plus because that implies the one. So that's lithium, that's one example. Okay. Now positive ions are called cations. Now that T there kind of reminds me of the plus sign. So it helps me remember cat ions are positive. The other thing it helps me remember is that cat ions are metals. They're in groups one, two and three in the periodic table. They're the ones with one, two or three electrons in their outer shell and they have a tendency to donate electrons. The other ones are anions. Here's an example of an anion. Okay. So oxygen has got an atomic number of eight. There's got eight electrons, two in the inner shell, six electrons in the next shell. There can fit eight electrons in the second shell. So therefore oxygen has a tendency to want to accept two more electrons. So therefore it can become more negative. Let's explain what I mean. Probably the best thing to do is to show on a board diagram. So it's currently got two electrons in its inner shell. And shell has got eight, six. So it's got six electrons in its outer shell. It can receive two more electrons. So if it receives two more electrons to have a full outer shell, it then has ten electrons in total. Only eight protons, eight positives. So what's the overall charge? There's two more negatives than there is positive. So it has an overall charge of two minus. And the way we express that is, oh, two minus. And they are called anions. Anions are negative ions. The N here reminds me of negative. Anions are negative. They're their non-metals. So again, the N for non reminds me of anions. Okay? Anions are negative and the non-metals.