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Chapter 21: Nuclear Chemistry. Chemistry 1062: Principles of Chemistry II Andy Aspaas, Instructor. Nuclear chemistry. Chemical reactions where the nuclei change Independent of chemical surroundings (i.e. it doesn’t matter what compounds the nuclei are part of)
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Chapter 21: Nuclear Chemistry Chemistry 1062: Principles of Chemistry II Andy Aspaas, Instructor
Nuclear chemistry • Chemical reactions where the nuclei change • Independent of chemical surroundings (i.e. it doesn’t matter what compounds the nuclei are part of) • Radioactive decay: unstable nuclei spontaneously disintegrate and give off radiation • Nuclear bombardment reactions: one nucleus is physically struck by another nucleus to cause a nuclear reaction
Nuclear equations • Nuclei only! • Nuclide symbols used to show: • Mass number, A • Atomic number, Z • For particles with no protons, the atomic number represents the charge • Ex. electron: • Total mass numbers and atomic numbers must be equal on both sides of reaction
Radioactivity • Alpha emission: ejection of a helium-4 nucleus • Occurs in nuclei where Z > 83 (transuranium) • Ex. • Beta emission: ejection of a high-speed electron • Occurs when N/Z is too large (N = # neutrons) • Ex.
Radioactivity • Positron emission: ejection of a positron • Positron: positively charged particle with same mass as an electron • Occurs when N/Z is too small • Ex. • Electron capture: adding an electron to the nucleus • Competes with positron emission when N/Z is too small • Ex.
Radiation • Gamma emission: emission of a gamma photon from an excited state nucleus • Metastable nucleus: excited nucleus a lifetime of at least one nanosecond • Ex. • Spontaneous fission: when a nucleus Z > 89 spontaneously breaks apart into other nuclei • Ex.
Predict the decay • Predict the form of radioactive decay the following nuclei will have, and if possible, write a nuclear equation
Nuclear bombardment reactions • Nuclei such as uranium-235 can be caused to split into several other nuclei if bombarded by a neutron • Fission produces more neutrons, which can go on to cause other uranium nuclei to split • The result is a chain reaction which releases the energy of neutron bombs and nuclear fission reactors
Pressurized light water reactor Most commondesign in US Prairie Island, MN Nuclear fission reactor
