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John Dalton and his atomic theory
John Dalton was born in England on Sept. 6, 1766. John was a teacher who loved to study weather, so he studied the actions of gases in the air. John Dalton eventually developed his own theory based on the way gases exert pressure. He said that a gas consists of individual particles. He believed that all matter is made up of individual particles, called atoms, which cannot be divided. He used wooden spheres which represents a tiny atom. Each sphere has a different mass. -
J.J. Thomson
J.J. Thomson learned more about atoms by using an electric curent to create his theory. Thomson used a device that has a center sealed glass tube from which all air has been removed. There is also a metal disk at each end. When turned on, a current creates a glowing beam. To test his idea, Thomson placed a plate on both sides which changed the beam's direction. He said that atoms are even smaller than Dalton's theory. -
Paul Drude and the Drude Model
Paul was the first to introduce the symbol "c" for the speed of light in a perfect vacum. In 1900, he created a strong model that showed the relationship between the electrical, thermoal, and optical properties of matter. -
The Saturnian Model-by Hantaro Nagaoka
Hantaro studied for years on Kinetic Theory of Gases and on the stability of Saturn's rings, this would later lead to the creation of his model of the atom in 1904. His model was based on an analogy of the explanation of Saturn's rings. His model made two predictions: 1) a very massive nucleus, 2) electrons revolving around the nucleus. His predictions were confirmed correct, but the details were not. So he abandon his theory in 1908. -
The Rutherford Model-by Ernest Rutherford
In 1911, Ernest theorized that atoms have their positive charge concentrated in a very small nucleus, which later created the Rutherford Model of atoms, because of his discovery during his gold foil experiment. He believed that a very small positively charged nuleus is orbited by electrons. He came with this model, when he discovered rare alpha particles with high deflection angles, these deflections were smooth and had high-ordered angles. -
Neils Bohr
Neils Bohr offically introduced is Theroy of Atomic Structure in 1913. His theory introduced the idea of electrons traveling orbits around the atom's nucleus and that the chemical properties of each element are determined by the number of electrons outside the nucleus. It also introduced the idea that an electron could drop from a higher energy-level to a lower one. This is known as the Quantum Theory. -
Erwin Schrodinger
Erwin made several contributions to the study of Physics. He wrote many books, including the well-known book called "What is life" which explained how complex molecules have genetic codes for living organisms....this book helped lead to the discovery of DNA double helix structure. In his first paper, it talked about what is known as the Schrodinger Equation...which gave a example of the wave equation for time independent systems. -
Ernest Marsden
Marsden did not have is own model, but he founded the Department of Scientific and Indusrial Research in 1926. He organized its research to focus on mainly agriculture. During World War 2, he worked on radar research, but died on Dec 15, 1970. -
James Chadwick
James discovered a unknown particle, which became known as the neutron....because of its lack of electric charge. His discovery made it possible the creation of uranium 235. His discovery also made it possible to create elements heavier than uranium in the lab. -
Louis De Broglie- And Thermodynamics
Louis had several theories involving mechanics and thermodynamics. According to Louis, the neutron and photon have rest masses that are non-zero, but still very low. He also believed that the true mass of particles is not constant, but variable, and that each particle can be represented as a thermodynamic machine the same as a cycle intergal of action. He created several mathmatical thermodynamic equations for his theories. -
Period: to
Time of the study of atoms
The study of atoms started around 489 B.C-November 18, 1962 -
Democritus
Democritus thought and believed thta all matter consisted of very small paricles that can not be divided, he called the atoms(This word comes from the Greek word: atomos, meaning "uncut"). He believed that there were specific atoms for different atoms, for example: he believed liquid atoms were round and smooth but solid atoms were rough. -
Aristotle
Aristotle was born on 384 B.C. and did not believe that there was a limit to the number of times matter could be divided. Instead, he believed that all substances, therefore matter, was built up from air, earth, fire, water....the four elements, which are a combination of four qualities- hot, cold, dry, wet.
