https://padlet.com/tplanojevic/u09xncxjg3x8706 en-us 2020-05-12 05:06:08 UTC 2020-05-12 05:33:56 UTC hello@padlet.com tplanojevic https://padlet.com/tplanojevic/u09xncxjg3x8706/wish/566566009 The first documented use of the word atom was in 5th century Greece by philosophers Leucippus and his student Democritus; They said that if they were to keep breaking a stone it would keep getting smaller and smaller until the pieces became indivisible. They said these atoms were specific to the materials they were made up of, had a solid structure and came in a variety of shapes.]]> 2020-05-12 05:07:44 UTC https://padlet.com/tplanojevic/u09xncxjg3x8706/wish/566566009 tplanojevic https://padlet.com/tplanojevic/u09xncxjg3x8706/wish/566570898 After a period of little discovery, Dalton started to build up an atomic theory. He stated that all matter is made up of atoms, all atoms of a given element are identical, a compound consists of two or more types of atom and chemical reactions occur when atoms rearrange. He also ordered all the known atoms in order of atomic weight.]]> 2020-05-12 05:13:34 UTC https://padlet.com/tplanojevic/u09xncxjg3x8706/wish/566570898 tplanojevic https://padlet.com/tplanojevic/u09xncxjg3x8706/wish/566574223 Cathode rays were shown to have been caused when low pressure gas is in a vacuum between two oppositely charged electrodes; when J.J Thompson used cathode rays he observed how they repelled negatively charged metal and attracted positively charged metal, concluding cathode rays were negatively charged. These cathode rays were called electrons and by the 1900s Thompson used this knowledge to propose his plum pudding model of the atom which stated atoms are composed of electrons surrounded by a region of positive charge.]]> 2020-05-12 05:17:16 UTC https://padlet.com/tplanojevic/u09xncxjg3x8706/wish/566574223 tplanojevic https://padlet.com/tplanojevic/u09xncxjg3x8706/wish/566582092 Rutherford wanted to demonstrate how radioactive substances decayed at a constant rate and observed this by firing alpha particles at gold foil, what occurred is that some particles passed through and some were deflected. He concluded that atoms have a concentrated mass in the nucleus which consists of positive and neutral charge surrounded by electrons.]]> 2020-05-12 05:26:25 UTC https://padlet.com/tplanojevic/u09xncxjg3x8706/wish/566582092