-
300
Aristotle
Aristotle’s theory made a great generalization off all matter being made of the four elements: fire, water, earth, and air. He also believed that there were four qualities to these elements: dryness, hotness, coldness, and moistness. -
400
Democritus
He was the first to creat an atomic model and hiss model of the atom depended on analogies from human senses.HIs model was just a round solid ball. Democritus didn't know about a nucleus or electrons, all he knew was that everything is made of atoms. -
Issac Newton
English physicist and mathematician who was born into a poor farming family. Luckily for humanity, Newton was not a good farmer, and was sent to Cambridge to study to become a preacher. At Cambridge, Newton studied mathematics, being especially strongly influenced by Euclid, although he was also influenced by Baconian and Cartesian philosophies. Newton was forced to leave Cambridge when it was closed because of the plague.Proposed a mechanical universe with small solid masses in motion. -
Jhon Dalton
He was nicknamed the "Father of Atomic Theory" because he was the first one to come up with the modern atomic model. His model was claimed to be one of the fundamentals of physics and chemistry and was the first model to have claims backed up by scientific experiments. He sees atoms as tiny, indestructible particles that have no internal structure. His model is like a tiny, solid sphere. -
Joseph John Thomson
In 1897 the British physicist Joseph John (J. J.) Thomson (1856–1940) discovered the electron in a series of experiments designed to study the nature of electric discharge in a high-vacuum cathode-ray tube, an area being investigated by numerous scientists at the time. -
Cathode Ray
Cathode rays are streams of electrons observed in vacuum tubes. If an evacuated glass tube is equipped with two electrodes and a voltage is applied, the glass opposite of the negative electrode is observed to glow, due to electrons emitted from and travelling perpendicular to the cathode the electrode connected to the negative terminal of the voltage. -
Hantaro Nagaoka
Though some atom models were proposed in the world of physics in the early 20th century, it was Hantaro Nagaoka, then professor at the University of Tokyo, who was the first to presented a Saturnian atomic model close to the presently accepted model. -
Rutherford
He discovers that an atom has a positve region which he called "nucleus", with electorns orbiting around it and the rest of the atom is mostly empty space. -
Rutherford's Gold-Foil Experiment
Rutherford reasoned that if Thomson's model was correct then the mass of the atom was spread out throughout the atom. Then, if he shot high velocity alpha particles (helium nuclei) at an atom then there would be very little to deflect the alpha particles. He decided to test this with a thin film of gold atoms. As expected, most alpha particles went right through the gold foil but to his amazement a few alpha particles rebounded almost directly backwards. -
Frederick Soddy
Frederick said with nuclei having the same number of protons but different numbers of neutrons. His theory of isotopes explains that different elements can be chemically indistinguishable but have different atomic weights and characteristics. -
Bohr
The Bohr Model has an atom consisting of a small, positively-charged nucleus orbited by negatively-charged electrons.Bohr Model is a modification of the earlier Rutherford Model, some people call Bohr's Model the Rutherford-Bohr Model. -
Werner Heisenberg
Werner Heisneberg discovered the Heisenberg Uncertainty Principle which states that the momentum and postion of a particle cannot be simultaneously measured with high precision. -
James Chadwick
He is an English physicist. James discover the neutron that has no charge. It is inside the atomic nuclei with protons. -
Atomic bomb
Leo Szilard conceived of the possibility of a controlled release of atomic power through a multiplying neutron chain reaction, and also realized that if such a reaction could be found, then a bomb could be built using it. Szilard described not only the basic concept of using neutron induced chain reactions to create explosions, but also the key concept of the critical mass. The patent was awarded to him - making Leo Szilard the legally recognized inventor of the atomic bomb. -
Enrico Fermi
Enrico Fermi made important discoveries about the atom, which led to the splitting of the atom (atomic bombs) and the harnessing of its heat into an energy source (nuclear energy).
