William Crookes

Chandler Elliott, Nicko Calcara, Josh Pezzulo, Ethan Williams

William Crookes

William Crookes was an English chemist and physicist who was most known for his experiments on the cathode ray phenomena. These "Crooke's Tubes" as they were named were designed to test electricity in low pressure gasses, and with different metals. Crookes discovered that as the gas pressure lowered the negative end (cathode) appeared to emit rays (later known to be free flowing electrons). He also changed the metals inside the tube and found the experiment remained the same. The work of Crookes led to other theories such as those by J. J. Thomson. Thomson further took Crooke's cathode rays and developed the idea of what they actually are, negatively charged particles called electrons.

(http://www.nndb.com/people/965/000100665/)

Eugen Goldstein

Eugen Goldstein was a German physicist who did extensive research on cathode ray tubes which were mainly used by William Crookes. Goldstein continued on with the research and discovered that along with the cathode rays(later to be electrons) which make up the negatively charged rays, there is a second ray that travels in the opposite direction from the anode in the tube. These rays are positively charged since they move in the opposite direction of the cathode rays. He knew that since the second ray was positively charged, it had to be made of a different particle then the first ray. This was the first discovery of the proton. The positively charged rays move through holes in the cathode, so Goldstein named these rays "canal rays". Goldstein noticed that the canal rays traveled directly through perforated holes in the cathode and stopped once they hit the glass past the cathode. This backed up his idea that the canal rays are positively charged. This discovery led to to the research and design of concave cathodes to produce more concentrated rays.

(http://chemed.chem.purdue.edu/genchem/history/goldstein.html)

Ernest Rutherford

To study for his graduate degree in 1899 ernest rutherford began testing the effect of xrays on various substances. With the discovery of radiation he turned his focus towards the study of uranium - a radioactive element. Rutherford discovered that with a strong beam of radioactive particles would have the power to pass through a small thin sheet of metal (0.000004 cm thick). The thinnest material he could use was gold which because it was extremely ductile could be stretched to extremely thin distances. When the particle beam went through the gold foil the beam scattered into different directions due to it hitting atoms. With this theory he was able to derive an equation to calculate the size of the nucleus based on the degree of the angle.

http://chemed.chem.purdue.edu/genchem/history/gold.html

Max Planck

Max Planck was a German philosopher who researched radiation. He showed that the problems with radiation were almost all considered electromagnetic in nature. From his previous studies he noticed the problem of the distribution of energy in the spectrum of radiation. His observations on the wavelength distribution of the energy emitted from a black body as a function of temperature were different from the observations of classical physics. He was then able to figure out the relationship between energy and the frequency of radiation. After that, he announced his findings, energy emitted by a resonator can only take on discrete quanta(minimal amount of a physical entity in an interaction). Planck's research and observations are known as a turning point for modern physics. It is said that some of Albert Einstein's theories are derived from Planck's work.

(http://www.nobelprize.org/nobel_prizes/physics/laureates/1918/planck-bio.html

J. J. Thomson

J. J. Thomson a British Physicist became famous through his discovery and identification of the electron, and even broader the first subatomic particle. Thomson based his research primarily off of that of William Crookes, and the cathode ray phenomena. Thomson interpreted the deflection of the rays by electrically charged plates and magnets as evidence of particles much smaller than atoms. Thomson suggested a model of the atom as a sphere of positive matter in which electrons spread out in this body of positive force. This model was referred to as the plum pudding model. Thomson was also the first to put a number on the charge-to-mass ratio of the electron. Due to Thomson's research one of his students, Ernest Rutherford went on and became known as the father of Nuclear Physics. Thomson's work also helped influence that of Robert Millikan, who was known for discovering the charge of the electron.

(http://www.chemheritage.org/discover/online-resources/chemistry-in-history/themes/atomic-and-nuclear-structure/thomson.aspx)

Robert Millikan

Robert Millikan an American experimental Physicist was most famously known for determining an electric charge carried by a single electron. Millikan got the groundwork for his work from that of J.J Thomson, who discovered the electron. Millikan worked on an oil-drop experiment in which he measured the charge of a single electron. Thomson had previously discovered the charge-to-mass ratio of the electron, but the actual values were unknown. Millikan's experiment measured the force on tiny charged droplets of oil suspended against gravity between two metal electrodes. Millikan then interpreted the results and was able to conclude that electrons had a negative charge. Millikan's work helped convince the owner of

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