Student Exploration: Nuclear Decay Vocabulary: alpha particle, atomic number, beta particle, daughter product, gamma ray, isotope, mass number, nuclear decay, positron, radioactive, subatomic particle Prior Knowledge Questions (Do these BEFORE using the Gizmo.) The chart below gives the locations, charges, and approximate masses of three subatomic particles. The approximate mass of each particle is given in universal mass units (u). Particle Location Charge Approximate mass Proton Nucleus 1 + 1 u Neutron Nucleus 0 1 u Electron Orbitals 1 - Ou The mass number of an atom is equal to the sum of protons and neutrons in the nucleus. A helium atom has 2 protons and 2 neutrons. What is the mass number of this atom? 2. The atomic number of an element is equal to the number of protons in each atom of the element. All helium atoms have 2 protons. What is the atomic number of helium? Gizmo Warm-up Key While most atoms are stable, some are radioactive, which Proton means that they have a tendency to undergo spontaneous Neutron nuclear decay. The decay of radioactive atoms generally Electron results in the emission of particles and/or energy. o Positron Several types of nuclear decay can be explored with the > Gamma Nuclear Decay Gizmo. On the Gizmo, check that Alpha decay and Uranium are selected. 1. Click Play ( ), and then click Pause ( " ) when the alpha particle is clearly visible. What is an alpha particle made of? 2. Click Play and observe. Besides the alpha particle, what else is emitted from the nucleus during alpha decay? Gamma rays are energetic electromagnetic waves; they are often emitted in nuclear decay