1. Nuclear Chemistry Nuclear Chemistry The study of nuclear reactions and their use in chemistry

2. Basic Definitions Nucleons - particles that reside in the nucleus – protons and neutrons Nucleons - particles that reside in the nucleus – protons and neutrons Isotopes – atoms of an element with the same number of protons but different numbers of neutrons Isotopes – atoms of an element with the same number of protons but different numbers of neutrons Mass Number – sum of p+ and n 0. Mass Number – sum of p+ and n 0. Atomic Number – number of p+ and e- in a neutral atom Atomic Number – number of p+ and e- in a neutral atom

3. A Brief History In 1896, Henri Becquerel expanded the field of chemistry to include nuclear changes when he discovered that uranium emitted radiation. Soon after Becquerel's discovery, Marie Sklodowska Curie began studying radioactivity and completed much of the pioneering work on nuclear changes. Curie found that radiation was proportional to the amount of radioactive element present, and she proposed that radiation was a property of atoms (as opposed to a chemical property of a compound). Marie Curie was the first woman to win a Nobel prize and the first person to win two (the first, shared with her husband Pierre and Becquerel for discovering radioactivity; the second for discovering the radioactive elements radium and polonium). In 1896, Henri Becquerel expanded the field of chemistry to include nuclear changes when he discovered that uranium emitted radiation. Soon after Becquerel's discovery, Marie Sklodowska Curie began studying radioactivity and completed much of the pioneering work on nuclear changes. Curie found that radiation was proportional to the amount of radioactive element present, and she proposed that radiation was a property of atoms (as opposed to a chemical property of a compound). Marie Curie was the first woman to win a Nobel prize and the first person to win two (the first, shared with her husband Pierre and Becquerel for discovering radioactivity; the second for discovering the radioactive elements radium and polonium). elementatoms compoundelements elementatoms compoundelements

4. Marie Curie Marie Curie Radiation – wave energy from any power source Radiation – wave energy from any power source Radioactivity – energy emitted from decaying atoms Radioactivity – energy emitted from decaying atoms

5. Stability of Atoms Most atoms are stable Most atoms are stable Certain nuclides are unstable because of the size of the atom or the ratio of protons and neutrons in the nuclei Certain nuclides are unstable because of the size of the atom or the ratio of protons and neutrons in the nuclei Radioisotopes – are atoms of an element that produce nuclear radiation ( they are radioactive ). Radioisotopes – are atoms of an element that produce nuclear radiation ( they are radioactive ).

6. Types of Nuclear Radiation Alpha Radiation (a) Alpha Radiation (a) An a particle contains 2 protons and 2 neutrons (and is similar to a He nucleus: ). An a particle contains 2 protons and 2 neutrons (and is similar to a He nucleus: ).protonsneutronsprotonsneutrons When an atom emits an a particle, the atom's atomic mass will decrease by 4 units (because 2 protons and 2 neutrons are lost) and the atomic number (z) will decrease by 2 units. When an atom emits an a particle, the atom's atomic mass will decrease by 4 units (because 2 protons and 2 neutrons are lost) and the atomic number (z) will decrease by 2 units. atom atomic massunitsprotonsneutrons atomic numberunitsatom atomic massunitsprotonsneutrons atomic numberunits

7. The element is said to 'transmute' into another element that is 2 z units smaller. The element is said to 'transmute' into another element that is 2 z units smaller. element unitselement units An example of an a transmutation takes place when uranium decays into the element thorium (Th) by emitting an alpha particle as depicted in the following equation: 238 234 4 An example of an a transmutation takes place when uranium decays into the element thorium (Th) by emitting an alpha particle as depicted in the following equation: 238 234 4alpha particlealpha particle U ----> Th + He U ----> Th + He 92 90 2 92 90 2