Atomic History timeline by Larry Vazquez https://padlet.com/vazquezl6/rf0iutpq8ghdk80r by larry vazquez en-us 2020-10-09 14:48:36 UTC 2025-10-08 11:59:58 UTC hello@padlet.com John Dalton 1803 vazquezl6 https://padlet.com/vazquezl6/rf0iutpq8ghdk80r/wish/816987473 Dalton believed that the atom was like a hard indestructible sphere. He then developed 4 postulates. 1, all mater is made of atoms and atoms are indivisible (not being able to divided further) and indestructible. 2 all atoms of a given element are identical in mass and properties. 3 compounds are formed by a combination of two or more different kinds of atoms. 4 a chemical reaction is a rearrangement of atoms.]]> 2020-10-09 15:03:47 UTC https://padlet.com/vazquezl6/rf0iutpq8ghdk80r/wish/816987473 J.J. Thomson 1904 vazquezl6 https://padlet.com/vazquezl6/rf0iutpq8ghdk80r/wish/817011333 J.J. Thomson is considered the founding father of the electron. while dalton had not yet known about the existence of subatomic particles (protons neutrons and electrons). with his cathode ray experiment, J.J. Thomson discovered the electron and that the electron had a negative charge.He theorized that the atom was a large positive sphere of matter with negative electrons randomly scattered within it, just as the raisins are scattered in the pudding.]]> 2020-10-09 15:10:19 UTC https://padlet.com/vazquezl6/rf0iutpq8ghdk80r/wish/817011333 Ernest Rutherford 1911 vazquezl6 https://padlet.com/vazquezl6/rf0iutpq8ghdk80r/wish/817030777 Rutherford conducted an experiment that we know today as the gold foil experiment. In this experiment, Rutherford took a beam of tiny particles called alpha particles and shot the beam at a thin sheet of gold foil (imagine something like aluminum foil that is made of gold, but much, much thinner). By doing this, Rutherford was trying to see what would happen when the particles reached the atoms of gold. From the experiment, he made 2 observations, 1 most of the alpha particles went through the gold foil.  2 a few of the alpha particles went through the gold foil. from these observations he drew 2 conclusions. 1 because most of the alpha particles went through rutherford concluded that the atom is mostly empty space. 2 because a few of the alpha particles bounced off of the gold atoms rutherford concluded that the particles must have bounced off of a small, dense, positively charged nucleus.]]> 2020-10-09 15:15:39 UTC https://padlet.com/vazquezl6/rf0iutpq8ghdk80r/wish/817030777 Niels Bohr 1913 vazquezl6 https://padlet.com/vazquezl6/rf0iutpq8ghdk80r/wish/817106823 In Niels Bohr's model of the atom, electrons can circle the nucleus only in particular orbits of fixed size and energy. To put it simply, he theorized that the electrons have only one circular path that they can follow, just as the planets circle the sun. These circular paths are called the electron orbits (see above). The term ORBIT is very important, being different that the term ORBITAL later used by De Broglie. Each of the orbits have a different amount of energy associated with them. As the orbits get further away from the nucleus, they have/possess more energy. Imagine that the nucleus is the sun and the electrons are the planets. Which planet would have the most energy according to Bohr?
What was the major problem here? We later find out that the electrons DO NOT actual travel in fixed paths as Bohr thought. De Broglie’s wave mechanical model will teach you more about what was later discovered.
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