Question

scientists have changed the model of the atom as they have gathered new evidence. one of the atomic models is shown below.

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.
the colors of light emitted from heated atoms had very specific energies.
experiments with water vapor showed that elements combine in specific proportions.
cathode rays were bent in the same way whenever a magnet was brought near them.

Explanation:

The atomic model shown (with a central nucleus and electrons in orbits) is related to the Rutherford - Bohr model development. The gold foil experiment (where alpha particles - positive particles - were aimed at gold foil and some bounced back) led to the discovery of the nucleus, which was a key step in moving from earlier atomic models (like the plum - pudding model) to models with a central nucleus. The other options: light emission (specific energies) is related to Bohr's model but not the transition to a model with a nucleus; water vapor and element combination are about chemical bonding, not atomic structure; cathode rays bent by magnets relate to electron discovery but not the nucleus - centered model.

Answer:

A. A few of the positive particles aimed at a gold foil seemed to bounce back.