Ernst Rutherford: Gold Foil Experiment=Discovery of the nucleus (+) It was quite the most incredible event that has ever happened to me in my life. It was almost as incredible as if you fired a 15-inch shell at a piece of tissue paper and it came back and hit you. On consideration, I realized that this scattering backward must be the result of a single collision, and when I made calculations I saw that it was impossible to get anything of that order of magnitude unless you took a system in which the greater part of the mass of the atom was concentrated in a minute nucleus. It was then that I had the idea of an atom with a minute massive center, carrying a charge. [2 ] [2 ] —Ernest Rutherford

Protons= 1800 times as big as electrons Electron Cloud  Empty Space Atomic #=Protons Atomic Mass: A P and/or N mass= 1 u= 1/12 mass of C 1u=1.67 e-27 kg Actual Mass: A x u Isotope=different masses=Same P/Differ N Nuclide= nucleus of isotope Strong Nuclear Force=Keeps nucleons together Electromagnetic Force= Keeps Nucleus and E together

If the atomic mass is changed so is the binding energy Einstein’s mass energy equivalent: E=mc become more stable become less stable 56= Fe-Sun’s natural nuclear reaction to increase size 57 & up=Natural nuclear reaction decreases

Alpha: He +2Paper Beta: Electron -1 Aluminum Gamma: Energy 0 Lead Half Life- the time it takes for ½ the substance to decay

An incident neutron bombards unstable nuclei until critical mass is reached until it splits

Isotope of Hydrogen combines with others to form Helium