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Joseph Proust - Constant Composition
The law stated that the composition of a substance is always the same, no matter where it was found or how it was made.Said table salt contained 1.5 more chlorine than sodium.Conclusion- The ratio by the mass of an element in a chemical compound always stays the same. -
John Dalton
John Dalton
Experiment: Dalton had many experiments but his main one was trying to figure out if atoms of elements would have different masses. He figured out through alot fo independent thinking since he didnt know the chemical formulas back then and he also figured out that spherical atoms have measurable properties which are more accurate then others.
Contribution:A book
Conclusion:That atoms are unchangeable and indestructable & that elements are characterized by the mass of there atoms. -
John Dalton discovered the Atomic Theory
John Dalton was one of the first scientists to decide that all matter is made up of small particles, or atoms. He did other studies about water vapor and mixed gases. From there Dalton decided that all matter, not only gases, must consist of small particles. Experiment Summary- Dalton didn't really use any experiments he used the laws to come up with his theories. Contribution- Dalton contributed the Atomic theory law and also Law of Partial Pressures. -
Joseph John Thomson
Experiment: The cathode ray. He observed how electric and magnetic fields asre effected using the CRT. The defection as the eam, same as negative charge behavior. Conclusion: Electrons have negative charge and are stuck to positive atoms. Contribution: The negative charged electron. www.iun.edu/~cpanhd/C101webnotes/.../dalton.html http://www.aip.org/history/electron/jjhome.htm: -
Joseph John Thomson discovered Charge/mass of the electron
Experiment- showed that a cathode ray consists of particles that have mass and negative charge. Contribution- The discovery of the electronConclusion- Electrons are negatively charged, but atoms have no charge. Atoms contain some positive charges that balance the the negative charges of the electrons. -
Ernest Rutherford
Experiment: He used the gold foil to shoot the particles at the center. Some bounced off and some went through. Conclusion: The center of the atom is positive and atoms contain empty space around the centerContribution: He founded the nucleus. http://chemed.chem.purdue.edu/genchem/history/rutherford.html -
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Ernest Rutherfordn- Proton
He noticed that when alpha particles we shot into nitrogen gas his scintillation detectors showed the signatures of hydrogen nuclei. He determind that the only place his hydrogen could have come from was nitrogen. Suggested that hydrogen nucleus was an elementary particle. This e named proton.Contribution- The charge of the proton being positive.Conclusion-One or more protons are present in each atom. -
James Chadwick
Beam was not deflected by electric or magnetic field. Conclusion: He concluded that the particles carried no electic charge. Contribution: The neutron. 1 Jan 1803
Conclusion: He did the model of the atomic theory and there was matter made up of atoms that are identical and cannot be destroyed.Contribution: Atoms of different elements differ. astr.gsu.edu/hbase/particles/neutrondis.htmlExperiment: -
James Chadwick discovered the Neutral Neutron
Experiment- Tried to figure out other particles that repelled. And found the neutrons.Contribution- found that this beam was not deflected by electric or magnetic fields.Conclusion- that the particles carried no elcetric charge. Further investigation showed that these neutral particles, which were named neurons, are part of all atomic nuclei. -
Murray Gell-Mann -Quarks
Suggested the existence of new elementary particles. Quarks are used has building blocks of neutrons and protons and objects in the study of the stucture of hadrons.Contributions- TheQuark model QCDConclusion- Protons and Neutrons have an underlying elementary particle.
