# Short Story Essay

1335 Words6 Pages
Mini Unit 13: Nuclear Chemistry! You are stardust….. I. What is the difference between a chemical reaction and a nuclear reaction? In chemical reactions In nuclear reactions 1. 1. 2. 2. 3. 3. 4. 4. 5. 5. II. Mass Defect and Nuclear Binding Energy Consider a helium-4 atom: (_______ protons, _________ neutrons, and __________ electrons) Recall: 1 proton = 1.007277 u, 1 neutron = 1.008665 u, and 1 electron = 0.000548 u We would expect the mass of a helium-4 atom to be as follows: 2(1.007277 u) + 2(1.008665) + 2(0.000548) = 4.032980 u However the observed mass of a helium-4 atom is 4.002596 u!!!!!! There is a difference of 0.030384 u between the observed mass and the calculated mass. This difference is called the mass defect. mass defect--the difference between the mass of a nucleus and the sum of the masses of its constituent particles. The mass defect is converted into energy by using Einstein's equation: E = mc2 nuclear binding energy-the energy released when a nucleus is formed from its constituent particles The nuclear binding energy is released when a nucleus is formed from the particles that compose it and must be supplied to a nucleus to separate it into its constituent particles. The higher the binding energy, the harder it is to break the atom. nuclear binding energy binding energy per nucleon = -------------------------------- # of nucleons Draw a Binding Energy Curve Here: So, iron-56 is the ____________ stable of all isotopes in the universe. the lightest and heaviest elements have the _________________ binding energy per nucleon (____________ stable) the elements with intermediate atomic weights have the __________ binding energy per nucleon (_____________ stable) III. Stability of Isotopes Isotopes that are stable tend to: