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445 BCE
Democritus
Democritus was one of the first people to discover and talk about the atom, or as he called it, the atomos. He believed that atoms were small solid, indestructable, invisible, and homogenous structures. He never performed an experiment to test these theories; he only wrote down his ideas. -
300 BCE
Aristotle
Aristotle declared that there were only four elements that exist (fire, earth, water, and air) and that they all had the same properties (wet, dry, hot, and cold). He also believed that no matter how many times you cut an object/material/substance/etc. in half, you still had a small piece of the original. He did not test out his theories and only had a philosophical view on them. -
John Dalton
John Dalton composed Dalton's Theory which stated that all matter is composed of atoms, which are excessively small particles, that atoms cannot be created, divided into smaller particles, or destroyed, and that in a chemical reaction, the atoms are changed in some way, whether that be in separation, combination, or rearrangement. His theory is one of the first theories dealing with atoms that was supported by scientific experimentation. -
William Crookes
William Crookes created the cathode ray, which lead to the development of the television. The cathode ray is basically a tub that has electrically charged particles shooting to and from the cathode disk and the anode disk (negative and positive metal disks) that creates a source of light. -
J.J Thomson
J.J Thomson created the ratio of charge to mass using Crookes' cathode ray. He also discovered subatomic particles, which are particles that are smaller than the atom. He was the first to find the electron, which is negatively charged. Thomson developed the plum pudding model of the atom, which presented that negative electrons were spread out evenly through a positive charge, which would make matter neutral. -
Robert Milikan
Robert determined that the electron carries a charge of -1.
