Radioactivity and Nuclear Reactions PS-2.2: illustrate the fact that the elements exist as stable or unstable isotopes PS-2.6: compare fission and fusion

Radioactivity  Nucleus Strong forces is holding nucleus together Strong forces is holding nucleus together 100X stronger then electrical force 100X stronger then electrical force Short range- protons and neutrons must be close together Short range- protons and neutrons must be close together

Radioactivity  Radioactivity Strong force is not strong enough to hold nucleus together…it breaks apart Strong force is not strong enough to hold nucleus together…it breaks apart Gives off matter and energy- nuclear decay Gives off matter and energy- nuclear decay All nuclei with more then 83 protons are radioactive All nuclei with more then 83 protons are radioactive  Isotopes Stable and unstable nuclei Stable and unstable nuclei Stable ratioStable ratio

Nuclear Decay  3 types of particles given off Alpha, Beta, and Gamma Alpha, Beta, and Gamma  Alpha Particles 2 protons and 2 neutrons 2 protons and 2 neutrons Same as what element? Same as what element? More massive then other 2 particles More massive then other 2 particles Most electric charge Most electric charge Least penetrating form of radiation Least penetrating form of radiation Stopped by paperStopped by paper

Nuclear Decay  Beta Particles Neutron decays into a proton and emits an electron Neutron decays into a proton and emits an electron The kicked out electron is the beta particle The kicked out electron is the beta particle Faster and more penetrating then alpha Faster and more penetrating then alpha Goes through paper but stopped by aluminum foilGoes through paper but stopped by aluminum foil

Nuclear Decay  Gamma Rays Most penetrating Most penetrating Electromagnetic waves Electromagnetic waves Highest frequency and shortest wavelength Highest frequency and shortest wavelength Thick blocks of dense material, lead or concrete, stop rays Thick blocks of dense material, lead or concrete, stop rays Cause less damage to biological molecules Cause less damage to biological molecules

Nuclear Reactions  Fission “to divide” “to divide” Large nucleus broken down into smaller mass Large nucleus broken down into smaller mass  Fusion 2 nuclei of smaller mass combine to form one nucleus of larger mass 2 nuclei of smaller mass combine to form one nucleus of larger mass