[Music] hi I'm welcome back to three times less than coal UK by the end of this video you should be able to like nuclear equations to show alpha and beta decay now a nuclear equation shows us what's produced when a radioactive nucleus decays this sounds tricky but it really isn't if you just learn the rules that I'm going to show you let's start by looking at alpha decay remember that an alpha particle has got two protons and two neutrons so it's the same of the nucleus of a helium atom scientists represent another particle by using the symbol for helium like this so looking at the atomic number which is 2 we can see that an alpha particle contains two protons the mass number 4 tells us that the earth particle has got 4 protons and neutrons added together so it must have 2 neutrons ok so let's look now the nuclear equation for alpha decay this showed the element radium William decays by releasing another particle and it produces the element radon now you could be asked to work out the atomic number and the mass number for the element produced by alpha decay so let's welcome and for the radon that's produced here well radium has an atomic number of 88 and here it is so the original radium atom had 88 protons the alpha particle has got 2 protons and there they are to work out the atomic number of the radon produced we've got to subtract 2 from 88 so that means that the atomic number for radon is 86 and there it is so this gives us the first rule for alpha decay giving alpha decay the atomic number increases by 2 now the mass number of the radium atom is 226 and there it is however the alpha particle released has a mass number of 4 this means that the mass number of the radon isotope produced by alpha decay must be 226 minus 4 222 and there it is so here's the second group of alpha decay during alpha decay the mass number decreases by four here's one for you to try this shows the alpha decay of the elements our Marisa this is the element that we find in smoke detectors when I'm a lithium undergoes alpha decay it forms neptunium I'd like you to work out the atomic number and the mass number of the neptunium so pause the video now and try this yourself okay the atomic number americium is 95 armed there it is the atomic number of another particles 2 subtracting 2 from 95 gives us an atomic number of 93 for neptunium the mass number on our SEM is 241 on the mass number of another particle as for subtracting 4 from 241 gives us a mass number of 237 for this isotope of neptunium ok so let's take a look now at nuclear equations for beta decay remember that in beta decay a neutron changes to a proton and an electron the electrons ejected from the nucleus and we now call it a beta particle so this shows the beta decay of an isotope of the element aluminium it's changing the silicon by releasing a beta particle because a neutron has changed to a proton the atomic number increases by 1 so in this case the atomic number of the silicon must be 14 and here it is in beta decay the mass number does not change that's because the total number of protons and neutrons in the nucleus stays the same so this silicon isotope has a mass number 29 here's the roof of beta decay in beta decay the atomic number increases by 1 but the mass number does not change here's one for you to try this shows iodine turning into xenon by releasing a beta particle I bet you to work out the atomic number and the mass number of the xenon atom so pause the video now and try this yourself okay and beta decay the atomic number increases by one so the atomic number of xenon must be 54 and there it is in beta decay the mass number does not change so in this case there's an isotope must have a mass number of 131 now we've looked at alpha and beta decay but what about gamma decay well in this case both the atomic number and the mass number are not changed at all remember your find plenty of questions on nuclear equations in my vision workbook and you can get that by clicking on the link above ok so hopefully now you should be able to write nuclear equations to show alpha and beta decay [Music]