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Jan 1, 1000
The Origin of Atomic Theory (Atoma) 5th Century B.C
The theory of matter being consisted of many small indivisible particles, Was started in the 5th Century B.C by a greek philospher named Leucippus of Miletus and his student Democritus. Atom comes from the word Atamos which in greek means indivisible. They also added that even though they were too small to see, that they were also solid with no internal structure. Color, taste, and other qualties were thought to be composed of atoms. -
Period: Jan 1, 1000 to
Atomic Theory Survives 5th Century B.C - Modern Day
Atomic Theory Surives through many centuries with the help of Aristoles writings going against it and other greek philosphers trying to continue it. -
Solid Sphere Model
The solid sphere model is the theory that atoms are seen as solid, indestructible spheres. This theory is used to explain how many chemicals work together to form new arrangements. Made By John Dalton. -
John Dalton
He determined the method for determining atomic weight. Included A list of atmoic weights for 21 elements. Was the first scientist to propose standard symbols for all the elements. Dalton's work was mainly about the chemistry of atoms—how they combined to form new compounds—rather than the physical, internal structure of atoms, although he never denied the possibility of atoms' having a substructure. -
Modern Atomic Theory - John Dalton
Started with the English Chemist and Meteoroligist John Dalton. He published A book on the Atmosphere and behaivor of gases. Daltons Theory of Atoms rested on four basic Ideas: Chemical Elements Were Composed of atoms. The atoms of an element are were identical in weight, the atoms of different elements had different weights, and atooms only combined in small whole-number ratios such as 1:1 1:2 2:1 2:3 to form compounds. -
J. J. Thomson
Disovered cathode rays in 1897. Actually, what Thomson discovered was that cathode rays were streams of negatively charged particles with a mass about 1,000 times smaller than a hydrogen atom. He claimed that these particles, which he called “corpuscles,” were the things that atoms were made from. He was a physicist the suggested his ideas. G.J Stoney Found the negatively charged electron. -
J.J. Thomson Part 2 Plum Pudding Model
Thomson Made a Plum-Pudding Model that shows where electrons. Thomson proposed (1904) a model in which the atom was a positively charged sphere studded with negatively charged electrons. It was called the “plum-pudding” model, since the electrons in the atom resembled the raisins in a plum pudding. This model did not survive unchallenged for long. -
Albert Einstein
At the time Physicists believed light was in waves. But, according to einstein the quanta behaved like discrete particles. The light particles were named photons. Atoms not only emit photons, but they can also absorb them. He discoverd the Photoelectric Effect. Einstein Also had the equation E=mc2 which was used by many physicists. -
Ernest Rutherford
Rutherford experiments with alpha rays mallowed him to describe the atom as a small nucleus with electrons orbiting around it. This model of the atom became the basis for the one that is still mostly used today. He discovered the proton in 1919. A proton carries a single positive electrical charge. Rutherford proposed the existence of a neutral subatomic particle called a neutron in 1920. -
Planetary Model
Also known as the Rutherford Model. This model was made because of J.J Thomson's so called "plum-pudding" model was incorrect. contained the new features of a relatively high central charge concentrated into a very small volume in comparison to the rest of the atom. This center point would later because the nucleus. -
Nuclear Model
The model states that the atom consists of a dense positive center and is surrounded by negatively charged electrons.
The nuclear model first discussed by New Zealand scientist Ernest Rutherford while working under J. J. Thomson.
Made by Niels Nohr -
Niels Bohr
He studied under both Thomson and Rutherford, made the model more advanced by proposing that electrons moved only in restricted orbital shells and the outer, higher-energy orbits determined the chemical properties of the elements. Bohr was able to explain the spectral lines of the elements by saying that electrons jumped from higher to lower orbits, they emit energy in the form of light. Bohr's theory became the basis for quantum mechanics, explaining the complex structure and behaivor of atoms. -
Robert Millikan
In 1916 Millikan took up with similar skill the experimental verification of the equaion introduced by Albert Einstein in 1905 to describe the photoelectric Effect. -
Louis de Broglie
In 1924 Frenchman Louis de Broglie thought about particles of matter. He thought that if light can exist as particles and waves, why couldnt atom particles act as waves?/ He showed what matter waves could behave like using einsteins equation E=mc2. Later Experiments proved him right. -
Wolfgang Pauli
Austrian Physicist Wolfgang Pauli Predicted in 1924 that the electron could spin like a top. While it orbits the nucleus. The electron could spin in wither of two directions. Spin consisted of a fourth quantum number. Electron spins. If one electron had a certain quantum number the other electrons couldnt have it. -
Werner Heisenberg + Schrödinger
In1925 Just before Schrödinger. German physicist Werner Heisenberg made a theory of his own named matrix mechanics. Which explained the behaivor of atoms. The two theories seemed to have entirely different sets of assupmtions yet they both worked. Heisenberg based his theory on matices that fit with the conception of electrons as particles. Schrödinger based his theory on waves. The results came up as matematically the same conclusion. Made electron Cloud because they didnt know the location. -
Erwin Schrödinger
In 1926 the Austrian physicist Erwin Schrödinger had an idea to make a model of an atom based on particle waves. His theory worked kind of like harmonic theory for a violin string except that the vibrations traveled in circles. He found it difficult to create a picture of an atom based on the waves because nothing else compares to them. Schrödinger named the waves that he discovered psi. -
James Chadwick
Discovered the neutral subatomic particle, the neutron in 1932. He was a former student of Rutherford. In contrast to the helium nuclei (alpha rays) which are charged which therefore repelled by the considerable electrical forces present in the nuclei of heavy atoms. Allowed cutting the nuclei of even the heaviest elements. He prepared the way for the fssion of uranium 235 and towards the atmic bomb being created. -
Citations Information
"Atomic Theory." Infoplease. Infoplease, 2007. Web. 22 Sept. 2013. "James Chadwick - Biographical." James Chadwick - Biographical. Nobel Foundation, n.d. Web. 22 Sept. 2013.
"History of Atoms." History of Atoms. Nobeliefs, n.d. Web. 22 Sept. 2013.
"Robert Andrews Millikan." Wikipedia. Wikimedia Foundation, 17 Sept. 2013. Web. 23 Sept. 2013. -
Modern Atomic Model
Main Atomic Model Used Today -
Citations Pictures
http://2012books.lardbucket.org/books/principles-of-general-chemistry-v1.0m/s05-introduction-to-chemistry.html
http://ganymede.nmsu.edu/tharriso/ast301/class20.html
"Happy Halogens." : More of a History Lesson! Happy Hallogens, n.d. Web. 22 Sept. 2013.
"E-10 Photoelectric Effect." - Physics 6510/4410 Wiki. N.p., n.d. Web. 23 Sep
"History of Atoms." History of Atoms. Nobeliefs, n.d. Web. 22 Sept. 2013.
"Robert Andrews Millikan." Wikipedia. Wikimedia Foundation, 17 Sept. 2013. Web. 23 Sept. 2013. -
Citations Pictures Part 2
"How Do I Make a Model of an Atom?" How Do I Make a Model of an Atom? N.p., n.d. Web. 23 Sept. 2013.
