Final answer:
The discovery of protons and electrons refuted the idea that the atom is indivisible and that it resembles plum pudding. Instead, it showed that atoms are composed of smaller particles with positive and negative charges. This discovery led to the development of new atomic models and a better understanding of atomic structure.
Step-by-step explanation:
The discovery of protons and electrons most directly refuted the idea that the atom is indivisible and that the atom resembles plum pudding. Prior to the discovery of subatomic particles, the prevailing belief was that atoms were indivisible and had no internal structure. However, the discovery of protons and electrons showed that atoms were composed of smaller particles with positive and negative charges. This refuted the idea that atoms were indivisible and led to the development of new atomic models that better represented the experimental evidence.
For example, J.J. Thomson's plum pudding model, which proposed that the atom was a spherical ball of positive charge with negatively charged electrons scattered throughout, was replaced by Ernest Rutherford's nuclear model. Rutherford's experiments with alpha particles showed that the atom had a small, dense nucleus containing protons and neutrons, with electrons orbiting around it. This new understanding of atomic structure replaced the idea of the atom resembling plum pudding.
Furthermore, the discovery of protons and electrons also provided evidence that the atom is electrically neutral. The positive charge of the protons is balanced by the negative charge of the electrons, resulting in an overall neutral atom.