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John Dalton
John Dalton(6 September 1766 – 27 July 1844),
was an English scientist best known for his work on the atomic theory. He proposed five main points for his atomic theory. His main ideas were: Elements were made by extremely small particles called atoms, all atoms of the same element are exactly the same, matter cannot be created or destroyed, atoms of different elements, can be combined to form compounds, and atoms can be rearranged, combined, or separated in chemical reactions. -
Dalton's Atomic Model
Dalton's atomic model was very important and a great contribution to science. His ideas of the atomic theory were very simple: all elements are formed by particles called atoms, all atoms of the same element are exactly the same, atoms of different elements can be told by the atomic weights, atoms of different elements can be chemically combined to make compounds, and matter cannot be created or destroyed.
"John Dalton." Wikipedia. Wkimedia Foundation, 09 Feb, -
William Crookes
Sir William Crookes(17 June 1832 – 4 April 1919) was a British scientist who contributed to the Atomic Theory. He contributed to the atomic theory by making a better vacuum pump that allowed him to produce cathode-ray tubes with a small residual gas pressure. "Cathode Ray Experiments." ThinkQuest. Oracle Foundation, n.d. Web. 03 Sept. 2013. http://library.thinkquest.org/28582/history/crayexp.htm. -
Crookes' Cathode Ray Tube
The cathode ray tube was William Crookes' contribution to the Atomic Theory. He discovered that the cathode rays had the following properties: the cathode rays travel in a straight line perpendicular to the cathode, they impart negative charge to objects they hit, they cause spinwheels to spin which means they have mass, magnetic fields change the path of the cathode rays, and rays caused reactions similar to those caused by light. This later led to the discovery of electrons. -
J.J. Thomson
(18 December 1856 – 30 August 1940)
In 1897, Thompson discovered the electron, after various suggestions of the atom being made of other fundamental units. He said that the electrons were 1000 smaller than the atom. He discovered by observing the properties of the cathode rays. His theory said that the electrons were small negative units sorrounding a positive sphere. -
J.J. Thomson "Plum Pudding" Model
Thomson's atomic model, also known as the plum pudding, suggests that the atom was a sphere with a positive charge sorrounded by small negative units known as the electrons. The electrons, or "corpuscles" like he called them, were the "plums" sorrounding the pudding. This was a reference to the British dessert the plum pudding. -
Ernest Rutherford
30 August 1871 – 19 October 19
He made a very important contribution to the atomic model. After doing an experiment with a gold-foil, he realized the atom had a very tiny, dense and positively charged nucleus, where most of the mass of the atom was. He then supposed that the electrons were outside of the nucleus in an empty space. "Rutherford Atomic Model." Encyclopedia Britannica Online. Encyclopedia Britannica, n.d. Web. 03 Sept. 2013. -
Rutherford Model
The Rutherford model suggest that the atom has a very tiny and dense nucleus, which is positively charged. It is in the nuclues where most of the atom's mass is. The electrons are outside of the nuclues and they are orbiting at distance in an empty space, it resembles to the planets orbiting the sun. -
Niels Bohr
7 October 1885 – 18 November 1962
Niels Bohr made great contributions to the atomic model and quantum mechanics. In 1922, he won the Nobel-Prize in physics for his work on the atomic theory. He developed good relationships with J.J. Thomson and Ernest Rutherford, which were the factor of making wanting to study the atomic model. It was while studying the previous models when he discovered that electrons travel in different orbits around the nucleus. -
Bohr Model
After revising the model made by Ernest Rutherford, Bohr made his own model suggesting different things. First, he said that electrons travel in defined orbits. He also suggested that the electrons could jump between these orbits, but could not freely spiral inwards or outwards in intermediate states. The electrons must also absorb or emit energy in order to change between orbits. "Bohr Model." Wikipedia. Wikimedia Foundation, 29 Aug. 2013. Web. 03 Sept. 2013. -
James Chadwick
James Chadwick made an incredible contribution to the atomic model was the discovery of the neutron. He won the Nobel Prize in 1935 due to this discovery. After studying the previous atom models, he discovered that electrons do not input weight to the atom, so there had to be something else making up the atom. Then he realized that the atom had some neutral particles, and he discovered the neutron. -
James Chadwick Model
This model is very similar to the previous model by Niels Bohr, but Chadwick added something to it, the neutron. The model still contains the nuclues with the positively charged electrons and the electrons orbiting around in orbits. The neutrons are grouped together with the protons. They have no charge at all, so the atom is still balanced. "James Chadwick." Wikipedia. Wikimedia Foundation, 09 Apr. 2013. Web. 03 Sept. 2013. -
Bibliography
"John Dalton." Wikipedia. Wikimedia Foundation, 09 Feb. 2013. Web. 01 Sept. 2013. http://en.wikipedia.org/wiki/John_Dalton. "John Dalton’s Atomic Model." Universe Today RSS. N.p., n.d. Web. 01 Sept. 2013. http://www.universetoday.com/38169/john-daltons-atomic-model/.
