6DaltonLaw of multiple proportions and the first model of the atom
7Concept ReviewThe atoms of elements A (blue) and B (orange) form two compounds shown here. Do these compounds obey the law of multiple proportions?Yes, the ratio of atoms represented by B that combine with A in these two compounds is (2/1):(5/2) or 4:5
9Cathode Ray Tube Evacuated tube Anode Cathode Battery − + The electric current creates the cathode ray (invisible) which spans the whole length of the tube. Its only visible because of the coating on the inside of the tubeBattery
11J.J. Thomson Charge to mass ratio and the Plum-Pudding Model Thomson found the mass to charge ratio of the beam particles to be ~2000 times smaller than that observed for Hydrogen ions. This result suggested that the particles were either extremely highly charged, or were much lighter than the lightest element, Hydrogen.
12R.A. Millikan Millikan Oil Drop An atomizer produces fine oil droplets The oil droplets fall through a hole in the first chamber as a stream of tiny dropletsX-rays negatively charge the oil dropletsAn applied voltage on two plates surrounding the oil droplets creates an electric field. The electric force pulls some droplets upwardThe rate at which the oil droplets are falling and rising between the two charged plates is measured through a microscope