Alpha decay of Polonium-210, nuclear decay reaction and released energy in MeV.
00:00 Alpha decay of Po-210: Polonium-210 is a daughter nucleus of Uranium-238 that alpha decays with a halflife of 138 days. In this problem, we are given the mass of Polonium-210 in atomic mass units, the mass of Lead-206 in atomic mass units, the mass of Helium-4 in atomic mass units and the atomic mass unit in MeV/c^2. We are going to write the nuclear reaction equation for the alpha decay of Polonium-210, then calculate the released energy in MeV for the nuclear decay reaction.
01:23 We write the nuclear decay equation for the decay of Po-210 by emitting an alpha particle. We use the periodic table to verify that Pb-206 is the daughter nucleus of the reaction, since lead has two fewer protons in the nucleus. The mass number is determined by subtracting the four nucleons that ran off with the alpha particle.
02:12 Now we compute the energy released in MeV. We need to find out how much mass has vanished in the nuclear reaction, so we take the mass of our initial nucleus Po-210 and subtract the combined mass of the daughter Pb-206 and the alpha particle He-4. We arrive at a number for the missing mass or mass defect in atomic mass units, then we convert the mass defect to MeV/c^2 by using the given atomic mass unit in MeV/c^2 (the derivation of this conversion factor is covered in another video). Once we have the mass defect in MeV/c^2 we apply E=mc^2 and obtain the energy released in the nuclear decay in MeV.
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