Question

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

A large black cross in a purple circle with a black line around the purple, with 10 small green balls dispersed within the purple circle.

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.
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.

Answer 1

Cathode rays were bent in the same way whenever a magnet was brought near them.

J. J. Thomson’s cathode-ray experiments showed the rays were negatively charged particles (electrons) much smaller than atoms. That evidence led him to replace the indivisible “solid” atom with the plum‑pudding model (a diffuse positive charge with embedded electrons). The other choices describe later experiments (gold‑foil → Rutherford nucleus, spectral lines → Bohr, quantum equations → electron cloud).