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500 BCE
Greeks
Democritus and Leucippus had the idea that all matter was made up of tiny indivisible particles or atoms. Aristotle then rejected Democritus's theory which was then buried away for thousands of years. -
Christiaan Huygens
Huygens developed the wave theory of light, which is important because his theory was eventually applied to the electron. -
Isaac Newton
Isaac Newton contributed to the atomic model by theorizing a mechanical universe, with small and solid masses in motion. He studied gases and the possibility of atoms existing and like boyle his work was impeded by the church. He proposed a mechanical universe where small solid masses were in motion, thus meaning that he thought that there were small pieces of mass ‘swimming’ everywhere. -
Dalton
Dalton's theory was that all matter was composed of atoms, individual and indestructible building blocks. He thought that all atoms of an element were identical, different elements had atoms differing size and mass. Dalton also based his theory on the law of conservation of mass and the law of constant composition.https://www.youtube.com/watch?v=kJ-6Qy05u_Q -
Gustav Kirchhoff
Gustav Kirchhoff discovered the spectrum analysis which is a technique that analyzes different chemicals that emit heat and lights from different elements. -
James Maxwell
Maxwell introduced the concept of electromagnetic field theory and made a connection between electromagnets and waves in light.
He showed that electromagnetic wave was possible. This was important because it showed our electrons might be able to perform like waves. -
Heinrich Hertz
Heinrich Hertz contributed to the atomic model by being the first physicist who conclusively proved the existence of the electromagnetic waves. Hertz also discovered the photoelectric effect, providing one of the first clues to the existence of the quantum world. The unit of frequency, the hertz, is named in his honour. -
Max Planck
Max Planck first introduced the notion of light quantum to explain the blackbody curve. This was the beginning of the quantum theory.https://www.youtube.com/watch?v=vhxjQ3-gYko -
Thomson
Thomson contributed to the atomic model by discovering the electron. He discovered the electron by experimenting with a crookes or cathode ray, tube. He was able to demonstrate that the cathode rays were negatively charged and he also studied positively charged particles in neon gas. -
Albert Einstein
Einstein formulated the theory of relativity which laid the basis for the atomic energy. He also mathematically proved the existence of atoms -
Rutherford
Rutherford overturned Thomson's model with his gold foil experiment (an experiment that used the alpha particles emitted by a radioactive element as probes to the unseen world of atomic structure). This taught us that the atom has a tiny but heavy nucleus -
Bohr
Bohr contributed to the atomic model by proposing a theory for the hydrogen atom, which was based on quantum theory. This means that the energy is transferred only in certain well defined quantities. Thus meaning that electrons should move around the nucleus but only within their prescribed orbits. A light quantum is then emitted when jumping from one orbit to another with lower energy.
