Lec03 Nuclear Reactions - NUCLEAR REACTIONS NUCLEUS The...

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LALaput Chemistry 16 Lecture 3 NUCLEAR REACTIONS NUCLEUS •The nucleus consists of protons and neutrons in a very small volume. Protons and neutrons are made of other fundamental particles called quarks . •Nuclei have a diameter of approximately 10 -12 cm and a density of approximately 2 x10 14 g/cm 3 . •The strong nuclear force binds the nucleus together at extremely short distances of 10 -13 cm NEUTRON-PROTON RATIO AND STABILITY 1. Nuclides denotes different nuclei. 2. Isotopes are nuclei that have the same number of protons but different neutron numbers. – Isotopes are the same element. •Experimentally, it can be shown that nuclei have a preference for even numbers of protons and neutrons. •Special stability is associated with certain proton and neutron numbers due to shell effects in nuclei similar to the s, p, d, and f shells in atoms •These proton and neutron numbers are called “ Magic Numbers ”: 2 8 20 28 50 82 126 •This is a plot number of neutrons (N) vs the number of protons (Z) For the stable nuclides ( the band of stability ) •For low AN, the most stable nuclides have N = Z. •For AN > 20, more stable nuclides have N > Z. RADIOACTIVE DECAY •Nuclei whose neutron-to-proton ratio lies outside the belt of stability experience spontaneous radioactive decay. •Decay type depends on where the nuclei is positioned relative to the band of stability. •Radioactive particles are emitted with different kinetic energies. –Energy change is related to the change in binding energy from reactant to products. EQUATIONS FOR NUCLEAR REACTIONS •Two conservation principles hold for nuclear reaction equations. 1. The sum of the mass numbers of the reactants EQUALS the sum of the mass numbers of the products. 2. The sum of the atomic numbers of the reactants EQUALS the sum of the atomic numbers of the products.
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Lec03 Nuclear Reactions - NUCLEAR REACTIONS NUCLEUS The...

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