CHEM101 Chapter Notes -Oil Drop Experiment, Electric Field, Atomic Number

• School: University of Alberta
• Department: Chemistry
• Course: CHEM101
• Professor: Yoram Apelblat

Document Summary

2. 4 the observations that led to the nuclear atom model. Cathode rays: stream of electrons: cathode = negative (negative cat), anode = positive, straight line/ bent in magnetic field/ towards positive plate in electric field. Observation: bends in mag. field, bends toward positive plate in electric field. Consists of negative particles: ray = identical regardless of cathode used particles found in all matter. 1897 thomson"s charge to mass ratio: weight of electron implied that atom = divisible into smaller particle. 1909 milikan"s oil drop experiment: experiments showed charge of droplets always multiple of a minimum charge, figured out mass to be 9. 109e-28 g = 9. 109e-31 kg. Rutherford"s gold foil experiment: shot beams of particles at thing sheet of gold foil -> sometimes particles would bounce back, discovery of the nucleus! Atomic number (z) - # of p+ Mass number (a) p+ + n0: number of neutrons = mass number atomic number = a z.