In alpha decay, a radioactive parent nucleus emits an alpha particle. An alpha particle is a helium-4 nucleus- that is, a nucleus that contains 2 protons and 2 neutrons, for a mass number of 4. The daughter nucleus therefore always has a mass number that is 4 less than the parent, and an atomic number that is 2 less than the parent. Here is an example of an alpha decay. 228 90 232 Th 88 Ra+He 4 This equation represents a thorium-232 nucleus decaying into a radium-228 nucleus and a helium-4 nucleus (i.e. an alpha particle). Notice that total atomic numbersthe number of protons, which is also the total charge-on both sides of the equation are equal. That is, there is a charge of +90e (where e is the charge of a proton) on one side, and a charge of +88e and +2e on the other: 90 = 88 + 2. Similarly, the total mass numbers (number of nucleons) on both sides of the equation are equal. That is, 232 = 228 + 4. Let's try a few examples. 238 A U nucleus undergoes an alpha decay. What is the atomic number of the daughter nucleus? 92 Remember that the atomic number is the number of protons. How many protons are in U? Remember that an alpha particle has two protons and two neutrons. How many protons remain after the alpha particle is emitted? 238 92 What is the mass number of the daughter nucleus? Remember that the mass number is the total number of nucleons (protons plus neutrons). How many nucleons are in U? Remember that an alpha particle has a total of four nucleons. How many nucleons remain after the alpha particle is emitted? 238 92 Write the symbol for this nucleus in full AX notation. Use the periodic table of elements linked below as needed. Z Using chemPad: To write chemical isotopes in the notation shown above, type the caret symbol ^ before superscript numbers and the underscore symbol _ before subscript numbers. Type the superscript and the subscript numbers before the chemical symbol. For example, to enter the symbol 233 chemPad XX" Pa 91 type out ^233_91Pa 1L Help Greek Polonium-210 decays via an alpha decay, according to the equation below. Fill in the daughter nucleus of the equation. chemPad XX 210 84 Po -> + He Greek Help Your answer contains an improperly or incompletely formatted chemical formula. Your answer contains improper superscript or subscript formatting.