Began the search for the description of matter, theorising that there eventually would be a point where matter could no longer be divisible, naming this substance, "atomos." He concluded the atomic model was similar to that of a billiard ball.
Approx. 1800 - 1809
Performed a number of experiments, eventually leading to the acceptance of the idea of atoms. He deduced that elements were composed of atoms; being indestructible and indivisible particles. Concluding that atoms of the same element are exactly alike and compounds were formed by the joining of atoms.
Provided the first hint that atoms were composed of smaller particles. The Thomson Model was an atomic model which theorised atoms were composed of a negatively charged substance with positively charged particles throughout. He came to this conclusion through his experiments, he named these smaller particles "corpuscles," today known as electrons.
Performed experiments, seemingly unravelling the mystery of the atomic structure; involving firing a stream of positively charged particles into gold foil. These experiments assisted in coming to the conclusion that atoms had a positively charged centre, known today as the nucleus.
Proposed adjustments to Rutherford's Model; according to Bohr's Model, electrons travelled in a definite orbit, encircling the nucleus, these electrons were a certain distance from the nucleus.
Conducted investigations on radiation, leading the discovery of the existence of neutrons and presence of such within the atom.
The present day model of the atomic structure is the Wave Model; based on wave mechanics; electrons do not move in definite orbits around the nucleus. It is impossible to determine the exact position of electrons within an atom. According to this theory, the nucleus is placed at the centre of the atom, with enough electrons encompassing the nucleus to ultimately make the atom neutral in charge.