Final answer:
Democritus proposed early ideas of atoms based on philosophical reasoning, whereas John Dalton developed a more scientifically robust atomic theory based on experimental evidence. Dalton's work marked a critical transition from philosophy to modern scientific inquiry in chemistry.
Step-by-step explanation:
The difference between Democritus and John Dalton in terms of discovering an atom lies in their methodologies and the robustness of their theories.
- Democritus, the Greek philosopher, suggested the concept of atomos which were indivisible particles. He believed that they had different shapes, sizes, and masses and that atoms were responsible for the properties of matter such as color and taste due to their arrangement, not due to the properties of atoms themselves.
- On the other hand, John Dalton, a British scientist, used experimental evidence to support his atomic theory. Dalton conducted experiments on the weights of elements and compounds, leading to his formulation of a scientific atomic theory. His work signified a transition from philosophical speculation to empirical science and introduced the idea that atoms of different elements are different in all respects, which laid the foundation for modern chemistry.
However, Dalton's theory suggesting that atoms of different elements are different in all respects was not completely accurate, as evidenced by the discovery that argon and calcium have the same atomic mass.