Welcome to Nuclear Chem It’s a bizarre-o world, where things are one thing, then they change into another. Leave your normalcy in the hall! Welcome to crazy! Pull out tables N and O now (like now without the “W”) Table N lists all of the radioisotopes that you need worry about in our class. Radioisotopes are radioactive, they are unstable atoms with a p+ to n° ratio that is out of synch with normal. They exist naturally, or they can be formed. As you recall, isotopes are chemically identical atoms with different numbers of neutrons, and therefore different masses. These are unstable isotopes, they literally cannot stay together the way they are, so they EMIT radioactivity (or radiation). Radiation, in our class, comes in 6 forms, all listed neatly in table O. These unstable atoms (radioisotopes) literally spit out parts of themselves, to change the ratio of p+ to n° in their nucleus, in an attempt to get stable. Doing this changes them from one kind of an atom to another, which is called transmutation. Transmutation can just happen naturally (natural transmutation), or people can cause it (artificial transmutation) Transmutation Is one of the weirdest things that you’ll learn from me. Atoms “wake up” one day as some unstable atom and on that day, for no obvious reason that this is the day, they will emit radiation (some of their nucleus) and become something else, a different kind of atom. That’s like if you go to bed tonight and wake up normally, but just after lunch (or before) you turn into a dog. A dog named Redox, or something else, like a fish maybe. That’s how weird it is. When an atom that is unstable, a radioisotope (as compared to many stable isotopes with different but stable numbers of neutrons), decides to emit radiation to change its nucleus to become more stable, the radiation comes in six forms we’ll learn about. All of the radiation forms are dangerous to living things. There is NO safe dose, all radiation is bad for your health. Radiation can cause cancer, or with a big enough dose, kill you in a few days, or even hours. Radiation sickness is when you get a big dose, which might or might not kill you. Until you do die, you’ll wish you were already gone. If you don’t die, you will likely end up with a variety of cancers, often of your glands or blood. Controlled forms of radiation are actually used for medical treatment, but let’s not get into that right now. All radiation is bad for living things all of the time. In our class radiation comes in these forms: Alpha particles, beta particles, gamma radiation (energy, not particles), protons, neutrons, and positrons (which are really cool and super duper odd) Let’s stop thinking too much and start doing some stuff, let’s look hard at table N. The first radioisotope is called gold-198 The 198 is the atomic mass of this isotope. It has 198 amu or 198 total protons plus neutrons in the nucleus. It’s on this list because that is an unstable ratio. What is that ratio you might ask (I was hoping someone would ask right now) 198 Au 198 79 This is really… 198 p+ plus n° Au this Of those 198 total, 79 are protons Table N says that this stuff will undergo β– decay, or beta decay. That means it emits a beta particle as radiation to adjust the proton – neutron ratio in the nucleus to get stable. Table O shows us the symbols. It’s a chemical reaction but with simple math to figure everything out. 198 79 Au 198 79 Au A beta particle of radiation + what ever then heck it turned into. Radiation emission causes transmutation 0 -1 e + 198 79 Au 0 -1 e + 198 80 Hg Radioactive gold atoms will emit beta particles and transmute into mercury-198 This has many names: 1. Radioactive decay 2. Spontaneous radioactive decay 3. Beta decay 4. Natural transmutation 5. Beta radiation emission Let’s do the next to radioisotopes, carbon 14, and then calcium 37. Carbon is also going to emit a beta particle, but watch out for that calcium, when it emits a positron particle of radiation, the math adds up differently. 14 C 37 Ca 0 -1 e + 0 +1 e + 14 6 C 0 -1 e + 14 7 N Carbon 14 is unstable so it naturally transmutes into nitrogen 14 and a beta particle. The radioactive carbon 14 emitted a beta particle to get more stable, and transmuted into a stable isotope of nitrogen, N-14. Radioactive Ca-37 emitted a positron from it’s nucleus and transmuted into K-37. The calcium 37 under went natural radioactive decay (positron decay) to become more stable, transmuting into K-37. 37 20 Ca 0 +1 e + 37 19 K Both cobalt-60 and cesium-137 undergo beta decay. The Iron-53 transmutes by emitting radiation called positron particles. Do the decay reactions now. (tables N and O without the “W”) 60 Co 137 53 Cs Fe Both cobalt-60 and cesium-137 undergo beta decay. The Iron-53 transmutes by emitting radiation called positron particles. Do the decay reactions now. (tables N and O without the “W”) 60 27 Co 0 -1 e 60 28 + Ni Cobalt 60 transmutes into nickel 60 by emitting a beta particle 137 55 Cs 0 -1 e + 137 56 Ba Cs-137 undergoes natural beta decay and transmutes into barium 137 53 26 Fe 0 +1 e + 53 25 Mn Iron-53 emits positron radiation and transmutes into a manganese isotope: Mn-53 Just for the record, a beta particle is sort of built like an electron, but is not an electron. It has no mass in our class, and it’s got a -1 charge like an electron, but it’s from inside a nucleus, so we call it a beta particle. Here’s the strangeness. It’s formed when a neutron which has no net charge emits a particle of no mass with a negative charge, leaving the neutron with the same mass as before, but without any negative charge (so now it’s positive). One neutron emits one beta particle, and the neutron is now a proton. No change in atomic mass, but a change in the number of protons. A positron is emitted from the nucleus as radiation by some isotopes. Positrons have a positive charge and no mass (like an opposite electron). A proton emits the positive part of itself, and it becomes a neutron. There’s no change in atomic mass, but a change in the proton to neutron ratio. 13 Alpha particles are much bigger, mass of 4 amu, containing 2 protons plus 2 neutrons. It’s got the same form as a helium nucleus, but it’s not helium, it’s an alpha particle. Remember the Gold Foil experiment, Rutherford shot alpha particles at the gold to see what these positively charged (+2) particles would do when they got to the gold atoms. 220 Fr What does this francium-220 do?? Look over table N. 220 87 Fr 4 2 216 85 He + At Francium 220 undergoes natural transmutation by emitting an alpha particle, and becoming astatine 216 Do the next alpha particle emitting radioisotope, which is plutonium-239 239 Pu 4 2 He 239 94 Pu 4 2 He + U 235 92 For classwork/homework, finish up the rest of table N as neatly as you can. Skip lines between each isotope, count carefully, peace love and nuclear chemistry. PS: for every time I hear the word NUKE-u-LAR, I deduct one point from your nuclear celebration score. The word is not NUKE-u-LAR, and if you pronounce it like that, you are not being cute, or speaking with an accent, you just sound like you don’t really know what you’re talking about and I will find it hard to cope. I’m serious! I will undergo some weird personal transmutation into a fish or something worse. What could be worse?