https://padlet.com/omar_m3/q2636znjw0nm From 400 B.C - 2000 en-us 2017-09-17 10:14:29 UTC 2023-02-07 23:32:40 UTC hello@padlet.com omar_m3 https://padlet.com/omar_m3/q2636znjw0nm/wish/188210295 Democritus hypothesized that all matter is made of extremely small, unbreakable circular units, that we today call atoms. The inspiration behind his theory was to answer the question 'How finely can one go cutting up matter?' At the time he had not claimed any solid information due to lack of experiments and research. Which, means no science was applied to answer the question, only curiosity and random ideas.
Democritus' atomic theory:


]]> 2017-09-17 10:18:02 UTC https://padlet.com/omar_m3/q2636znjw0nm/wish/188210295 omar_m3 https://padlet.com/omar_m3/q2636znjw0nm/wish/188337311 Aristotle was a Greek philosopher who helped extend the theory of the atom. His idea was that all matter consisted of 4 elements; fire, water, earth and air. He thought that these 4 elements were everywhere, however in very small particles. Considering Aristotle was a philosopher, he didn't perform any experiments and had no scientific evidence behind the theory. 
This is Aristotle's atomic theory]]> 2017-09-18 06:35:39 UTC https://padlet.com/omar_m3/q2636znjw0nm/wish/188337311 omar_m3 https://padlet.com/omar_m3/q2636znjw0nm/wish/188342995 - http://timelineoftheatom.blogspot.ae/p/2.html
- https://www.barcodesinc.com/articles/timeline-on-atomic-structure.htm
- https://the-history-of-the-atom.wikispaces.com/Aristotle
- http://atomictimeline.net/index.php
- http://www.abcte.org/files/previews/chemistry/s1_p5.html
- http://study.com/academy/lesson/robert-millikan-biography-atomic-theory-oil-drop-experiment.html
- http://www.abcte.org/files/previews/chemistry/s1_p6.html]]> 2017-09-18 07:01:47 UTC https://padlet.com/omar_m3/q2636znjw0nm/wish/188342995 omar_m3 https://padlet.com/omar_m3/q2636znjw0nm/wish/188451750 2017-09-18 13:27:33 UTC https://padlet.com/omar_m3/q2636znjw0nm/wish/188451750 omar_m3 https://padlet.com/omar_m3/q2636znjw0nm/wish/188453310 2017-09-18 13:30:39 UTC https://padlet.com/omar_m3/q2636znjw0nm/wish/188453310 omar_m3 https://padlet.com/omar_m3/q2636znjw0nm/wish/188454619 Dalton's theory was the first to describe atoms and their properties. He also stated that all matter is made up of atoms that are indivisible. His theory revolved around the law of conservation of mass and the law of constant composition. He began the idea that the atoms in liquids are identical in mass and properties, and the same thing goes for any given element.]]> 2017-09-18 13:32:44 UTC https://padlet.com/omar_m3/q2636znjw0nm/wish/188454619 omar_m3 https://padlet.com/omar_m3/q2636znjw0nm/wish/188741108 2017-09-19 05:03:27 UTC https://padlet.com/omar_m3/q2636znjw0nm/wish/188741108 omar_m3 https://padlet.com/omar_m3/q2636znjw0nm/wish/188855961 In 1897, Thomson discovered the electron during his research. He used a chathode ray to determine the charge to mass ratio of an atom.

Thompson discovered that atoms have positively charged cores, with negatively charged particles within them. ]]> 2017-09-19 12:47:22 UTC https://padlet.com/omar_m3/q2636znjw0nm/wish/188855961 omar_m3 https://padlet.com/omar_m3/q2636znjw0nm/wish/188913369 2017-09-19 14:28:27 UTC https://padlet.com/omar_m3/q2636znjw0nm/wish/188913369 omar_m3 https://padlet.com/omar_m3/q2636znjw0nm/wish/188913520 Millikan calculated the charge of a single elctron in 1908. This discovery allowed us to understand greater information about the structure of the atom and the atomic theory.
Millikan used an oil drop to calculate the charge of an atom.]]> 2017-09-19 14:28:45 UTC https://padlet.com/omar_m3/q2636znjw0nm/wish/188913520 omar_m3 https://padlet.com/omar_m3/q2636znjw0nm/wish/188927443 Niels introduced the idea that an atom is a positively charged nucleus that is orbitted by electrons. He calculated possible energy levels for the atom to orbit. 

]]> 2017-09-19 14:52:53 UTC https://padlet.com/omar_m3/q2636znjw0nm/wish/188927443 omar_m3 https://padlet.com/omar_m3/q2636znjw0nm/wish/188928706 2017-09-19 14:55:05 UTC https://padlet.com/omar_m3/q2636znjw0nm/wish/188928706 omar_m3 https://padlet.com/omar_m3/q2636znjw0nm/wish/188938123 2017-09-19 15:12:51 UTC https://padlet.com/omar_m3/q2636znjw0nm/wish/188938123 omar_m3 https://padlet.com/omar_m3/q2636znjw0nm/wish/188940737 Using mathematical equations, erwin calculated the likelihood of an electron being in a certain position.

This model is called the quantum mechanical model of the atom.]]> 2017-09-19 15:16:49 UTC https://padlet.com/omar_m3/q2636znjw0nm/wish/188940737 omar_m3 https://padlet.com/omar_m3/q2636znjw0nm/wish/188964163 2017-09-19 15:56:18 UTC https://padlet.com/omar_m3/q2636znjw0nm/wish/188964163