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Unformatted text preview: Chem Final Study Guide Units of Mass AMU- 1/12 the mass of a carbon atom with 6 protons, 6 neutrons, and 6 electrons J.J, Thomson Experiment- found the charge to mass ratio of an electron by observing the deflection of an electron beam in a magnetic or electric field Millikan oil-drop experiment- found the charge of an electron by observing oil droplets charged by an X-ray source Rutherford Experiment- bombarded gold foil with alpha particles to observe the presence of a tiny, dense nucleus. Alpha particles are helium nuclei. Determining that the electron is a spinning particle- nonuniform magnetic field produces two detections Atomic number- number of protons in the nucleus o I t defines a chemical element Mass Number- the sum of protons and neutrons Atomic mass- mass of one isotope Atomic weight- mass average of all naturally occurring isotopes Isotopes- same number of protons but different numbers of neutrons are isotopes of the same element, isotopes have virtually identical chemical properties Nuclide- same as an isotope but refers to the nucleus instead of the whole atom Radioactive elements spontaneously emit energy. Three types of emission: alpha, beta, and gamma Nuclei having an even number of protons have more stable isotopes than those with an odd number of protons Most common number of isotopes per element is 1 Mass spectrometer separates different isotopes of an element o Positively charged ions are deflected by a magnetic field: the heaviest ions are deflected the least and the lightest ions the most. o Plotted as atomic mass versus relative abundance All elements with atomic number greater than 83 have unstable nuclei (they are radioactive) 1 eV= 96.485 KJ/Mole 1 amu= 931.5 MeV mass difference between component atomic parts and total atom is the binding energy of the nucleus Gas Laws PV=nRT Charles Law- Volume is proportional to temperature Boyles Law-Volume is inversely proportional to pressure (used monometer) The densities and molar volumes of liquids vary because sizes of molecules are important Different gases have about the same molar volume because the actual size of the molecules is basically irrelevant Mercury Barometer- single tube (pressure is a measure of the liquid height in Hg its 760mm) Daltons law of partial pressures- total pressure is the sum of the partial pressures (partial pressures depend on mole fractions) Ideal gas law applies to individual gas: PAV=nART=(nA +nB) A RT PBV=nBRT=(nA +nB) B RT PTOTALV = (nA + nB) RT Real gases use van der waals equation Part 1: The pressure inside a sample of gas is larger than the measured pressure, which represents attraction between the bulk of the sample and those molecules close to the walls Part 2: the internal volume available for atomic motion is less than the measured volume because each atom occupies a finite volume A- parameter larger and more variable Percent error- 1-calculated/ideal...
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- Spring '10