Lately, as I have driven around, I have seen a bunch of billboards about Radon. You can actually pay people to come to your house and get rid of the radon. Having taught about nuclear chemistry a few times, my initial reaction was very skeptical. What did these “professionals” know that I didn’t, and what’s with all the hype lately. Well, I’ll tell you……
The leading cause of lung cancer is smoking, everyone knows this, or should. But does everyone know the second leading cause is radon exposure? There are more than 150,000 deaths from lung cancer each year and, depending on who is reporting the statistic, usually around 90% (give or take a few percentage points) of those are caused by smoking. It is reported that around 21,000 of those deaths are caused by radon exposure. Which seems to be the cause of all of the hype. That are a lot of people suffering from radon exposure and it is usually occurring in their own home.
Here are some basics about Radon….
It is found in the noble gas family on the periodic table. Check out my post on the periodic table. It has some great info on why that is one of the coolest (aka most useful) charts in science (or life).
Its position in this family, pegs it as nonreactive, since it has all of the electrons that it likes and it would take quite a bit of energy to pull one of them away from it. That doesn’t mean that this element is stable in all respects. It is radioactive, so instead of its electrons forming bonds and wreaking havoc, like fluorine or chlorine, its nucleus is unstable (its protons and neutrons, people. There aren’t any membranes or other particles or anything like that, it is just a location for the protons and neutrons) and falls apart. Its most stable isotope, Radon-222, only takes a little more than 3 days to fall apart. This is called radioactive decay and it releases ionizing radiation. There are a few different types of decay and the one that Radon prefers is alpha decay. Alpha decay is when a couple of protons and a couple of neutrons fall out of the nucleus. (btw, it is pronounced nu-cleeeee-us, not nu-cu-lus) There is a special name for this group of rogue particles, I bet you can’t guess what it is….. it is an alpha particle, but it can also be known as Helium. If you check the periodic table (come on, don’t you just have one hanging in your room?) you will see that helium has 2 protons and if you subtract that from 4, the atomic mass, you will find that there are 2 neutrons as well. So what is so ionizing (aka bad, or detrimental to our health) about helium? I thought we love to put it in balloons or breathe it in and make our voices sound funny. So, are you asking yourself if you are going to get lung cancer from singing like a chipmunk? Let me just say upfront that you are safe from getting lung cancer when we are talking about your everyday average helium atom. (So that’s a “No” you aren’t getting lung cancer from sucking in helium from your little brother’s birthday balloons) Helium is also considered a noble gas and thus doesn’t react with anyone or anything and is considered stable. The alpha particle, on the other hand, is ionizing radiation. It is different from regular old helium in one way, it doesn’t have electrons. I know what you are thinking, “of course it doesn’t have electrons because there weren’t any falling out of the nucleus during radon’s radioactive decay. Only protons and neutrons come from the nucleus, silly”. Due to this terrible situation the alpha particle finds itself in, it will steal electrons from anyone or anything (any atom or compound actually) it runs into first. This theft causes that particular atom or compound to then need electrons to stabilize itself and you can see how there is a chain reaction of ions being created. Hence the term, ionizing radiation. It makes ions, and unless you need to conduct electricity in solutions, ions just tend to cause trouble.
There are 3 main types of radioactive decay.
Alpha (⍺), Beta (𝛽) and Gamma (𝛾). Atoms that undergo radioactive decay in one of these three methods, can also give off ionizing radiation. Radon-222, the kind that is in your basement, will undergo alpha decay and release an alpha particle. This transforms, actually it transmutes, radon into polonium. Check the periodic table again. Since radon loses 2 protons, it also loses its identity. It was #86 but since 2 of those protons are gone, it is now #84 on the periodic table (polonium). Polonium also undergoes alpha decay and we are left with……… 2 more protons have left thus instead of 84 protons we now have 82 which is atomic number 82 on the periodic table……… lead. This next decay transmutes lead into Bismuth. Can you find that on the table? Bismuth actually has 1 more proton than Lead. So where does that proton come from?
Are you thinking, “I thought this was decay not growth?”
Well, let me tell you what just happened……..
The atom we were dealing with was lead-214 which isn’t stable and thus undergoes a beta transmutation. Beta decay is really interesting because one of the neutrons actually turns into a proton. That is seriously cool quantum mechanics. So the mass of the atom stays the same but its chemical and physical properties all change due to the change in the atomic number (which is the number of protons). Bismuth-214 is also unstable and undergoes another beta transmutation which turns it back into polonium. The difference between this polonium and the one we had before is the atomic mass. This is polonium-214 and before it was polonium-218. Polonium-214 isn’t quite as stable as the more massive isotope with a half-life of less than a second instead of about 3 minutes. When it transmutes, it releases that alpha particle and is much more stable. Can you figure out which atom it turns into? We know that an alpha particle has 2 protons and 2 neutrons (at least by now I hope that we all know that. If not, there is always re-reading to be done or you can check out the “Ask A Tutor” page where we can definitely go over this more) Now, we subtract 2 from the atomic number and 4 from the atomic mass number (2+2=4, right? This is a quick reminder that adding up all of the protons AND neutrons will give you the atomic mass number of an atom. So we had better add up the protons and neutrons of the alpha particle to find out its Atomic mass number) Polonium is #84 so we subtract 2 and get #82 which is lead. We can then subtract 4 from 214 and get 210. Yay! We figured out which atom it turns into. Lead 210.
I hope you are very proud of what you have just done. Not a lot of people know how to handle alpha and beta decay but now you can count yourself as one of them.
Lastly, we have gamma decay. I saved the best for last. Gamma radiation isn’t a particle, it is a light wave. Just like sunlight, or the light from your cellphone screen but this light is ionizing. It has enough energy to knock an electron off of an atom. That’s not good if that atom is helping to make up your skin. It can cause quite a bit of damage to you. Gamma decay, therefore, doesn’t change any particles and thus doesn’t change the element’s identity. Gamma decay is just an atom’s way of blowing off a little steam, so to speak. Releasing that gamma radiation, lowers the overall energy of the atom, thus making it more stable.
Well, you started reading this article because you were worried about radon in your basement but now you know all about alpha particles and beta decay and what really goes on in radioactive elements.
Are you still wondering about that radon?
Since it is radioactive and can harm you if you breathe it in, it is definitely worth measuring and determining how much you have in your house. There are super cheap test kits that you can buy and place in your house. Then, you will need to send them to a lab for analysis to find out how much radon is in your basement. The EPA recommends less than 4 picocuries/liter (that is a crazy measurement, right? Just think of a unit you are more familiar with like miles per gallon. How many miles your car can drive with each gallon of gas. Now compare that to how this unit works in a similar fashion) Curies are the measurement of how many times a certain radioactive sample decays in a minute and by adding the prefix “pico” makes it an even smaller measurement (like inches are smaller than feet or like centimeters are smaller than meters). So in this case, it just means 4 picocuries, or decays, in one liter of air.
Below are a few links about Radon and where to get test kits and find professionals. I hope you find them helpful. I also hope you feel like you have a better understanding of what they are talking about too.