Nuclear Chemistry Chapter 21

Nuclear Chemistry Study of nuclear reactions and their uses in chemistry nuclear reactions – change in matter originating in the nucleus of an atom radioactive – nuclei spontaneously changing and emitting radiation

Nuclear Chemistry Subatomic particles are involved proton and neutron  nucleons Can be determined by atomic number and mass number Same atomic number, different mass number  isotope Radioactive nuclei  radionuclide Atoms with radionuclides  radioisotopes

Nuclear Chemistry Radionuclides Radioactive decay Unstable Emit particles and electromagnetic radiation Radioactive decay

Radioactive Decay 1 – alpha radiation α Helium - 4 particles, aka alpha particles 42He 23892U  23490Th + 42He

Alpha radiation - Sample What product is formed when radium-226 undergoes alpha decay? 22688Ra  22286Rn + 42He What element undergoes alpha decay to form lead-208? 21284Po  20882Pb + 42He

Radioactive decay 2 – beta radiation β High speed e- 0-1e or 0-1 β 13153I  13154Xe + 0-1e

Radioactive decay 3 – gamma radiation γ High energy photons 00γ Energy lost when nucleons reorganize

Radioactive decay 4 – positron emission Same mass as e-, opposite charge 01e 116C  115B + 01e Positron can convert proton to neutron

Radioactive decay 5 – electron capture Capture of electron by nucleus from electron cloud 0-1e consumed, not formed

Electron Capture - Sample Write nuclear equations for the following processes: a) Mercury-201 undergoes electron capture b) Thorium-231 decays to form protactinium-231 a) 20180Hg + 0-1e  20179Au b) 23190Th  23191Pa + 0-1e

Electron Capture-Sample 2 Write a balanced nuclear equation for the reaction in which oxygen-15 undergoes positron emission 158O  157N + 01e

Nuclear Transmutations Nuclei changed by being struck by neutron or nucleus Commonly represented by listing in order the target nucleus, the bombarding particles, the ejected particles, the product nucleus 147N (α,p)178O 147N + 42He  11p + 178O

Nuclear Transmutations-Sample Write the balanced nuclear equation for the process summarized as 2713Al (n, α) 2411Na 2713Al + 10n  42He + 2411Na Using shorthand notation, write the nuclear reaction 168O + 11H  137N + 42He 168O (p, α) 42He