Alright. So now that we've introduced isotopes in this video, we're going to talk a little bit about radioactive isotopes. And so radioactive isotopes are really just defined as isotopes themselves that are really, really unstable and break down over periods of time by emitting energy in the form of rays or particles. And so if we take a look at our image down below over here on the left-hand side, notice that we're showing you an example of the radioactivity of a carbon 14 isotope. And so this here represents the nucleus of the radioactive atom, more specifically, the nucleus of the carbon 14 isotope, which we know from our last lesson video is going to have a total of 6 protons in its nucleus and a total of 8 neutrons in its nucleus since its mass number is 14.

Now carbon 14 is a radioactive isotope, meaning that it is really really unstable and will break down over time by emitting energy in the form of rays or particles. And so this arrow right here represents released energy, and this arrow down here represents released subatomic particles. And so once again, this radioactive atom is going to decay and break down over time. Now the rate that radioactive atoms break down is pretty consistent, and so from that consistency scientists can calculate what's known as the half-life. The half-life is defined as the exact amount of time it takes for exactly half of all radioactive atoms in a sample to break down.

And so these radioactive isotopes actually have several important uses in human life, and so for example radioactive isotopes are used in medicine such as, for giving MRIs, and they can be used in other fields of medicine as well, so they're very, very important, for that aspect. But radioactive isotopes can also be used for what's known as radiometric dating of fossils, and this is basically how scientists can determine how old dinosaur bones are, by just looking at the amount of radioactive isotopes that are present in the fossils and then using the half-life to calculate or approximate approximately how old the fossils are. Now we're not going to talk about that exact process but you should be aware in your biology course that radioactive isotopes will break down over time. They can have a half-life which is the time it takes for half of it to break down, and they can be used in medicine and for radiometric dating of fossils. And so this here concludes our lesson on radioactive isotopes, and we'll be able to get a little bit of practice in our next few videos.

So I'll see you all there.