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Modern Physics Radioactive Decay Radioactive Decay Look at the periodic table given to you. Find element with the atomic number 6 What is it? Radioactive Decay The element with the atomic number 6 is Carbon Look at the atomic mass below the word Carbon What is it? Radioactive Decay The mass is 12.011 amu. Remember that protons and neutrons are about 1 amu each Therefore you can assume that there are 12 particles in the nucleus, 6 protons 6 neutrons Radioactive Decay You would then write the nuclear symbol for Carbon – 12 as 126C (with the 6 over the 6) Radioactive Decay Find Oxygen on the chart. Radioactive Decay Find Oxygen on the chart. Atomic number 8. How many protons does oxygen have? Radioactive Decay Find Oxygen on the chart. Atomic number 8. How many protons does oxygen have? Yes – 8 protons How many neutrons does the most common Isotope of Oxygen have? Radioactive Decay Find Oxygen on the chart. Atomic number 8. How many protons does oxygen have? Yes – 8 protons How many neutrons does the most common Isotope of Oxygen have? 8 Radioactive Decay Find Argon on the chart. Number 18 Radioactive Decay Find Argon on the chart. Number 18 How many protons does it have? Radioactive Decay Find Argon on the chart. Number 18… How many protons does it have? 18 I think you are getting it. How many total Protons and Neutrons? Radioactive Decay Find Argon on the chart. Number 18… How many protons does it have? 18 I think you are getting it. How many total Protons and Neutrons? 40 Radioactive Decay • Write the symbols for the following atoms most common isotope. • Fluorine(9) • Neon(10) • Sodium(11) • Radon(86) • Uranium(92) Radioactive Decay • Review from yesterday • An atom is stable (not radioactive) if it is in the belt of stability • An atom is unstable (radioactive) if it is outside the belt of stability • All elements beyond number 83, Bismuth are unstable - WHY? Radioactive Decay • Above element 83, the protons are farther and farther away from each other in the nucleus, therefore requiring a greater nuclear force to overcome the electrostatic repulsive forces. The nuclear force is not strong enough to hold together the protons when more than 83 of them are packed into a nucleus. Radioactive Decay • Three types of radioactive decay • 4α 2 • 0 -1 • 0 +1 alpha particle decay also shown as 24He ß Beta particle decay (An electron from a neutron) ß Positron emission (a positively charged electron) • ϒ gamma ray High energy electromagnetic waves Radioactive Decay • 4α 2 alpha particle decay also shown as 24He An alpha particle is two protons and two neutrons bound together and emitted from the nucleus. Alpha particle are identical to a helium nuclei and have a charge of 2+ Radioactive Decay • 0 1 Beta particle decay ß • A beta particle is actually an electron emitted from the nucleus. To create a beta particle, a neutron converts itself into a proton and ejects the right combination of quarks to make an electron Radioactive Decay • 0 +1 Positron emission ß • Elements below the belt of stability have too many protons. To decrease the number of protons, a proton emits a positron, or positively charged electron Radioactive Decay • Not a decay per say, but another way to get rid of too many protons, is Electron Capture • In electron capture, an inner orbital electron is captured by the nucleus of its own atom. This electron combines with a proton and forms a neutron. Radioactive Decay Radioactive Decay
