https://padlet.com/echen201/77gpebp2a32m Scientists whose discoveries led us to our current understanding of the atom en-us 2017-09-18 02:55:36 UTC 2026-03-11 05:13:00 UTC hello@padlet.com https://padletuploads.blob.core.windows.net/prod/221741161/3ed577cf19790feccaea0cd07237fffd/atom_hi.png echen201 https://padlet.com/echen201/77gpebp2a32m/wish/188393595 Democritus proposed the first atomic theory. He came up with the idea that everything was made of atoms and that atoms were indivisible and indestructible. ]]> 2017-09-18 10:38:17 UTC https://padlet.com/echen201/77gpebp2a32m/wish/188393595 echen201 https://padlet.com/echen201/77gpebp2a32m/wish/188395923 Dalton was the first scientist to use evidence to support his proposal for the atomic theory. His atomic model was a solid sphere. ]]> 2017-09-18 10:47:05 UTC https://padlet.com/echen201/77gpebp2a32m/wish/188395923 echen201 https://padlet.com/echen201/77gpebp2a32m/wish/188398031 Thomson was the first scientist to introduce that the atoms was made up of even smaller things, particles. His discovery was based off his experiment on cathode rays. Prior to this experiment, scientists knew that cathode rays had a negative charge, but Thomson wanted to find out more about cathode rays to create his atomic model. ]]> 2017-09-18 10:56:14 UTC https://padlet.com/echen201/77gpebp2a32m/wish/188398031 echen201 https://padlet.com/echen201/77gpebp2a32m/wish/188403207 Rutherford was the first scientist to introduce the idea of protons and a nucleus of an atom. To create his model of an atom, Rutherford conducted the gold foil experiment. This experiment began with the creation of alpha particles by using a box that contained a radioactive source. ]]> 2017-09-18 11:21:27 UTC https://padlet.com/echen201/77gpebp2a32m/wish/188403207 echen201 https://padlet.com/echen201/77gpebp2a32m/wish/189159739 2017-09-20 03:23:55 UTC https://padlet.com/echen201/77gpebp2a32m/wish/189159739 echen201 https://padlet.com/echen201/77gpebp2a32m/wish/189159790 2017-09-20 03:24:18 UTC https://padlet.com/echen201/77gpebp2a32m/wish/189159790 echen201 https://padlet.com/echen201/77gpebp2a32m/wish/189159831 2017-09-20 03:24:33 UTC https://padlet.com/echen201/77gpebp2a32m/wish/189159831 echen201 https://padlet.com/echen201/77gpebp2a32m/wish/189159860 2017-09-20 03:24:48 UTC https://padlet.com/echen201/77gpebp2a32m/wish/189159860 echen201 https://padlet.com/echen201/77gpebp2a32m/wish/189161015 2017-09-20 03:33:51 UTC https://padlet.com/echen201/77gpebp2a32m/wish/189161015 echen201 https://padlet.com/echen201/77gpebp2a32m/wish/189161567 Also, he believed that there were many different atoms. For example, if a stone was cut into the smallest possible pieces, the pieces would be stone atoms. Only theory was used to come to Democritus' conclusion.]]> 2017-09-20 03:38:29 UTC https://padlet.com/echen201/77gpebp2a32m/wish/189161567 echen201 https://padlet.com/echen201/77gpebp2a32m/wish/189161703 2017-09-20 03:39:29 UTC https://padlet.com/echen201/77gpebp2a32m/wish/189161703 echen201 https://padlet.com/echen201/77gpebp2a32m/wish/189162693 2017-09-20 03:47:55 UTC https://padlet.com/echen201/77gpebp2a32m/wish/189162693 echen201 https://padlet.com/echen201/77gpebp2a32m/wish/189163337 2017-09-20 03:53:12 UTC https://padlet.com/echen201/77gpebp2a32m/wish/189163337 echen201 https://padlet.com/echen201/77gpebp2a32m/wish/189163814 He used evidence from his experiment where he took elemental gases and observed how they bonded with each other. From this experiment he discovered that all matter is made is of atoms, which are indivisible/indestructible and identical in mass and properties. He also stated that compounds are created by a combination of two or more different kind of atoms and chemical reaction are created by a rearrangement of atoms. ]]> 2017-09-20 03:57:35 UTC https://padlet.com/echen201/77gpebp2a32m/wish/189163814 echen201 https://padlet.com/echen201/77gpebp2a32m/wish/189163959 2017-09-20 03:58:35 UTC https://padlet.com/echen201/77gpebp2a32m/wish/189163959 echen201 https://padlet.com/echen201/77gpebp2a32m/wish/189164182 2017-09-20 04:00:27 UTC https://padlet.com/echen201/77gpebp2a32m/wish/189164182 echen201 https://padlet.com/echen201/77gpebp2a32m/wish/189164384 2017-09-20 04:02:04 UTC https://padlet.com/echen201/77gpebp2a32m/wish/189164384 echen201 https://padlet.com/echen201/77gpebp2a32m/wish/189164583 In this experiment, there are two electrodes which are connected to a high voltage source to create a cathode ray. Near the electrodes, he put two electric charged plates to finalize that cathode rays were made up of charged particles. The final conclusion from the experiment was that cathode rays were filled with negative particles which are attracted to positive particles. To back up this claim, Thomson did the experiment twice. The first time, the cathode ray bent downwards towards the positive charged plate, because the negative ray was attracted to the positive, however people could have claimed that gravity was pulling the ray down. To clarify that the ray was lighter than air, Thomson flipped the position of the charged plates, and sure enough, the ray bent upwards towards the positively charged plate. ]]> 2017-09-20 04:03:40 UTC https://padlet.com/echen201/77gpebp2a32m/wish/189164583 echen201 https://padlet.com/echen201/77gpebp2a32m/wish/189164769 From this experiment, he came up with the Plum Pudding diagram. This diagram shows that an atoms is filled with negatively charged particles, electrons which are the plums of the diagram, and the pie part, or the empty space is positively charged. The major conclusions of this experiment was that atoms are neutral and negative electrons are present in all atoms. ]]> 2017-09-20 04:04:53 UTC https://padlet.com/echen201/77gpebp2a32m/wish/189164769 echen201 https://padlet.com/echen201/77gpebp2a32m/wish/189164918 2017-09-20 04:05:49 UTC https://padlet.com/echen201/77gpebp2a32m/wish/189164918 echen201 https://padlet.com/echen201/77gpebp2a32m/wish/189165312 2017-09-20 04:08:22 UTC https://padlet.com/echen201/77gpebp2a32m/wish/189165312 echen201 https://padlet.com/echen201/77gpebp2a32m/wish/189165623 2017-09-20 04:10:20 UTC https://padlet.com/echen201/77gpebp2a32m/wish/189165623 echen201 https://padlet.com/echen201/77gpebp2a32m/wish/189166218 From this experiment, Rutherford's model had the nucleus in the center which contained protons and orbits around the nucleus which contained electrons. ]]> 2017-09-20 04:13:50 UTC https://padlet.com/echen201/77gpebp2a32m/wish/189166218 echen201 https://padlet.com/echen201/77gpebp2a32m/wish/189166643 In front of the box was a piece of one atom thick gold foil that the alpha particles would go through. In front of the gold foil was a detector that detected where the alpha particles that went through the gold foil hit. Many alpha particles traveled through the gold foil un- deflected, but some particles got deflected by the gold foil through small angles. Since the alpha particles deflected the gold foil, Rutherford concluded that the foil was positive because the alpha particle repelled. Through this experiment, Rutherford concluded that atoms have empty space, a very dense center, which is the nucleus, and that there are positively charged particles, protons. ]]> 2017-09-20 04:17:06 UTC https://padlet.com/echen201/77gpebp2a32m/wish/189166643 echen201 https://padlet.com/echen201/77gpebp2a32m/wish/189166677 2017-09-20 04:17:23 UTC https://padlet.com/echen201/77gpebp2a32m/wish/189166677 echen201 https://padlet.com/echen201/77gpebp2a32m/wish/189166892 2017-09-20 04:19:04 UTC https://padlet.com/echen201/77gpebp2a32m/wish/189166892 echen201 https://padlet.com/echen201/77gpebp2a32m/wish/189167076 2017-09-20 04:20:27 UTC https://padlet.com/echen201/77gpebp2a32m/wish/189167076 echen201 https://padlet.com/echen201/77gpebp2a32m/wish/191514365
Image of Democritus:
https://the-history-of-the atom.wikispaces.com/Democritus
Image of Democritus/ Dalton Atom Model:
http://www.timetoast.com/timelines/cjg-ekm-tjga-s-atomic-theory-timeline
Image of Democritus Atomic Theory: https://www.visionlearning.com/en/library/Chemistry/1/Early-Ideas-about-Matter/49
Image of John Dalton:
https://www.biography.com/people/john-dalton-9265201
Image of Dalton's Atomic Theory:
https://www.universetoday.com/38169/john-daltons-atomic-model/
Image of JJ Thomson:
https://the-history-of-the-atom.wikispaces.com/J.J.+Thomson
Image of Thomson's Experiment:
http://study.com/academy/lesson/jj-thomsons-cathode-ray-tube-crt-definition-experiment-diagram.html
Image of Thomson's Plum-Pudding Model:
https://www.electrical4u.com/thomsons-plum-pudding-model/
Image of Ernest Rutherford:
https://www.nobelprize.org/nobel_prizes/chemistry/laureates/1908/rutherford-bio.html
Image of Alpha Particles:
http://physicsopenlab.org/2016/02/11/alpha-α-radioactivity/
Image of Rutherford's Experiment:
https://socratic.org/questions/what-did-rutherford-s-gold-foil-experiment-prove
Image of Rutherford's Atomic Model:
https://www.electrical4u.com/rutherfords-atomic-model/
Image of Niels Bohr:
https://en.wikipedia.org/wiki/Niels_Bohr]]> 2017-09-27 03:15:19 UTC https://padlet.com/echen201/77gpebp2a32m/wish/191514365 echen201 https://padlet.com/echen201/77gpebp2a32m/wish/191645236 2017-09-27 13:16:59 UTC https://padlet.com/echen201/77gpebp2a32m/wish/191645236 echen201 https://padlet.com/echen201/77gpebp2a32m/wish/193592242 2017-10-03 18:25:30 UTC https://padlet.com/echen201/77gpebp2a32m/wish/193592242 echen201 https://padlet.com/echen201/77gpebp2a32m/wish/193593706 Electrons should move around the nucleus but only in prescribed orbits. When jumping from one orbit to another with lower energy, a light quantum is emitted. Bohr's theory could explain why atoms emitted light in fixed wavelengths.]]> 2017-10-03 18:28:33 UTC https://padlet.com/echen201/77gpebp2a32m/wish/193593706