1.  Nuclear Chemistry

2. Nuclear Vs. Chemical Reactions  Nuclear reactions involve a change in an atom’s nucleus, usually producing a different element.  In nuclear reactions, different isotopes of an element do not normally behave similarly  Rates of nuclear reactions are unaffected by temperature and catalysts

3. Nuclear Vs. Chemical Reactions  Nuclear reactions are independent of the chemical form of the element  Energy change accompanying nuclear reactions are much larger and comes from destruction of mass  In nuclear reactions, mass is NOT strictly conserved. Some mass is transferred into energy, E=mc 2

4. Nuclear Radiation  Alpha particle, α - emission of an He nucleus, resulting in a decrease in both mass and atomic number.

5. Beta Particle  Beta radiation, β - emission of a beta particle (an electron from the nucleus) resulting in an increase in atomic number.  How can an electron come from the nucleus?  A neutron has turned into a proton, thereby ejecting an electron

6. Nuclear Radiation  Positron Emission- emission of a positively charge electron (positron) from the nucleus, resulting in a decrease in the atomic number. A positron has the same mass as an electron, but opposite in charge. Inside the nucleus a proton is being converted into a neutron.

7. Radiation  Gamma radiation, γ -This is the photon that carries the energy (higher than x-rays) that is emitted. Gamma rays have no mass or charge. It’s strictly energy and provides no changes in the isotope.

8. Alpha, Beta, and Gamma Radiation

9. Nuclear Stability and Decay  The stability of a nucleus depends on its neutron to proton ratio.  For elements with low atomic numbers the ratio is about 1. For those with higher atomic numbers it’s ~1.5  Example: C-12, N-14, O-16 all 1:1  Example Pb-208

10. Nuclear Stability  All nuclei that have an atomic number greater than 83 are radioactive because they have too many protons and neutrons.  Most of these heavy elements emit alpha particles in order to increase the proton:neutron ratio and therefore, stability  Fission vs Fusion  Fusion-combining of nuclei  Fission-splitting of nuclei

11. Half Life  Half life is the time required for ½ of the nuclei of a radioisotope sample to decay  Half lives can be as short as a fraction of a second to as long as a billion years.  Example: Radon has a half life of 3.8 days, how long would it take for a 10 gram sample of radon to decrease to 2.5 grams?