Step-by-step explanation:
J.J. Thomson made several significant contributions to the development of the atomic theory. His most notable contribution was the discovery of the electron.
In 1897, using cathode ray experiments, Thomson demonstrated that cathode rays (electrons) could be deflected by magnetic and electric fields. This led him to propose the "plum pudding" model of the atom. According to this model, atoms were thought to be composed of a positively charged "pudding" with embedded negatively charged electrons, similar to plums in a pudding.
Thomson's work provided important evidence for the existence of subatomic particles and challenged the previously held view that atoms were indivisible. His discoveries and model of the atom contributed to our understanding of the fundamental structure of matter and laid the foundation for further developments in atomic theory.
Additionally, Thomson's research and advancements in gas discharge tubes (cathode ray tubes) played a crucial role in the subsequent discoveries of other subatomic particles, such as protons and neutrons, by scientists like Ernest Rutherford and James Chadwick.
Overall, J.J. Thomson's discovery of the electron and the subsequent model of the atom significantly contributed to our understanding of atomic structure and paved the way for further advancements in the field of atomic theory.