Scientists have changed the model of the atom as they have gathered new evidence. One of the atomic models is shown below. Overlapping red and blue balls in the center with a circular fuzzy green cloud outside them. What experimental evidence led to the development of this atomic model from the one before it? A few of the positive particles aimed at a gold foil seemed to bounce back off of the thin metallic foil. Experiments with water vapor showed that elements combine in specific proportions. Equations were used to identify regions around the nucleus where electrons would likely be. Cathode rays were bent in the same way whenever a magnet was brought near them.