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John Dalton 1766-1844
John Dalton was the first to create the atomic theory, which became a basis for many new ideas to come. Dalton's theory established four fundamental principals of atoms, number one being that they were tiny particles that could not be split up into anything smaller. -
Sir William Crookes June 17, 1832 - Apr. 4, 1919,
Crookes discovered the element thallium, he also invented the radiometer, and studied radioactivity, -
Dmitri Mendeleev 1834-1907
Dmitri Mendeleev was the first to organize the elements into a table that grouped the elements by similar characteristics. His table was an explanation to certain elements having similar properties as other elements showing a pattern across each group and throughout each family. However, a couple of elements did not fit the pattern of his table. Mendeleev had to make adjustments so that everything worked. -
Eugen Goldstein
He used a CRT to study "canal rays" which had electrical and magnetic properties opposite of an electron. Eugen Goldstein (September 5, 1850 – December 25, 1930) was a German physicist. He was an early investigator of discharge tubes, the discoverer of anode rays, and is sometimes credited with the discovery of the proton. -
Marie Curie Nov. 7, 1867 - July 4, 1934
Curie, along with her husband Pierre, discovered polonium and radium and, after Pierre's death, the further development of X-rays. -
Sir William Crookes June 17, 1832, Apr. 4, 1919
Crookes discovered thallium, and also invented the radiometer, and studied radioactivity. -
Niels Henrik David Bohr
Combining Rutherfford's description of the nucleus and Planck's theory about quanta, Bohr explained what happens inside an atom and developed a picture of the atomic structure. Bohr's greatest contribution to modern physics was the atomics model. The Bohr model shows the atom as a small, positively charged nucleus surrounded by orbiting electrons. -Kerrianna Jadunandan -
Henry Moseley
Before his finding, atomic numbers had been thought of as an arbitrary number, based on sequence of atomic weights. Moseley also predicted a number of missing elements and their periodic numbers in the periodic table. Today, we know that the atomic number gives the number of protons (positive numbers) in the nucleus. This discovery was made by Moseley. He found that certain lines in the X-ray spectrum of each element moved te same amount each time you increased the atomic number by 1. -
Thomson 1856-1940
In 1897 the British physicist discovered the electron. He was conducting a series of experiments designed to study the nature of electric discharge in a high-vacuume cathode ray tube. In 1904 he suggested a model of an atom as a sphere of positive matter in which electrons are positioned by electro static forces -
Marie Curie Nov. 7, 1867 - July 4, 1934
Maire Curie along with her husband Pierre, discovered Polonium and Radium, and went later on to work on X-Rays. -
Millikan 1868-1953
He carried out experiments to find out the quantity of an electrons charge. He tried to find this out by conducting an oil drip experiment. From the experiment he found out that an electron has one unit of negative charge and it's mass is 1/1840 of an hydrogen atom. -
Rutherford 1871-1937
He proposed that the atom is mostly empty space. The Rutherford atomic model is known as the nuclear atom. In the nuclear atom the protons and neutrons are located in the positively charged nucleus. -
James Chadwick 1891 - 1974
Chadwick discovered the neutron, the neutral subatomic particle inside of all atoms, and won a nobel prize. -
Bibliographies
Wilbraham, A., Education, I., Staley, D., Matta, M., & Waterman, E. (2012). Atomic Structure. In Pearson chemistry (pp. 102-182). Boston, MA, Florida: Pearson. Buescher, L. (n.d.). Atomic Structure Timeline. Retrieved October 5, 2015. (n.d.). Retrieved October 5, 2015. Chemistry Explained. (n.d.). Retrieved October 5, 2015. Sir William Crookes. (n.d.). Retrieved October 5, 2015.
