NUCLEAR RADIATION

What is radioactivity? A process where an unstable nucleus emits one or more particles of energy in the form of radiation. That means an element on the periodic table has atoms that are unstable. This is called an ISOTOPE – atoms that have the correct number of protons as said in the periodic table square, but a different number of neutrons. Nuclear radiation – charged particles or energy emitted by an unstable nucleus (ex. uranium, thorium, radium, radon)

Natural Radiation Radiation from natural sources Sun Gas (radon) Potassium in our food and water Uranium/radium/thorium found in Earth’s crust Cosmic rays No, these do not have levels high enough to be concerned about!

Man-made Radiation Radiation from synthetic (not natural) sources TV Smoke detectors Building materials Lanterns X-rays Tobacco Nuclear medicine Computer screens Some of these can have high amounts of radiation, specifically in the medical field.

Types of Radiation Alpha particles α – positively charged particles made of 2 protons and 2 neutrons, do not travel far b/c they are massive. They remove electrons from material as they pass through so alpha particles lose energy and slow down. Symbol: Basically, alpha radiation is radiating of helium atoms Charge : +2 (has 2 protons) Beta particles β – a negatively charged electron emitted during radioactive decay, travels farther than an alpha particle, faster moving and smaller. Still ionizes (removes electrons as it passes through matter). Symbol: Beta radiation is radiating of an electron Charge: -1 (it is one electron)

Gamma rays γ – discovered by Marie Curie in 1898, NOT made of matter but made of electromagnetic energy such as visible light and x-rays. They are high energy and travel farthest, causes most damage. Symbol: γ Charge: none, because they are rays Neutron emission – the release of a high energy neutron, do not ionize b/c they are neutral.

Comparing the types of radiation, you can see how alpha particles are big so do not travel far or through many things. Beta are smaller and can get through more. Gamma, since they are rays, are the most dangerous. These are in x-rays which is why you must wear lead vests to protect your organs when having those procedures done.

Nuclear Decay When an unstable nucleus gives off an alpha or a beta particle and the number of protons or neutrons changes, thus changing the original element. Recall: ALPHA PARTICLE BETA PARTICLE

Decay Problems Written as equations similar to chemical equations. Before decay = reactants. After decay = products. You will need a periodic table to look at. Ex. Alpha decay of 226 4 88 Ra  2 He + __________ Since it is alpha decay, you see the alpha particle used.

226 4 88 Ra  2 He + __________ Since it is the alpha particle plus something you have to subtract. Ask yourself “226 minus 4 is what?” and “88 minus 2 is what?” Fill in the new element info and look up on the periodic table what the new element is (bottom number). 226 – 4 = 222 so… 226 4 222 88 – 2 = 86 88 Ra  2 He + 86 Rn *Look up element 86, it is Rn.

Try this one Alpha decay of 208 4 84 Po  2 He + ____________ 208 – 4 = 204 84 – 2 = 82 Look up element 82. It is Pb. So… 208 4 204 84 Po  2 He + 82 Pb

Beta decay problem Ex. Beta decay of 14 0 6 C  -1 e + _____________ Notice since it is BETA decay we use the beta particle. Solve the same way. 14 – 0 = 14 6 – (-1) = 7 (subtracting a negative is like adding it) Look up element 7. So…. 14 0 14 6 C  -1e + 7 N

Try this one Beta decay of 87 0 37 Rb  -1 e + ___________ 87 – 0 = 87 37 – (-1) = 38 Look up element 38. It is Sr. So… 87 0 87 37 Rb  -1e + 38 Sr Now, it is your turn to do a sheet of them on your own. ASK for help if you do not understand. Turn it in when finished.