Atomic Theory Scientists - Timeline by Juan Ignacio Alende https://padlet.com/jalende/q2j69zychh531374 by Juan Alende en-us 2021-10-01 10:56:59 UTC 2021-10-04 10:48:50 UTC hello@padlet.com Democritus jalende https://padlet.com/jalende/q2j69zychh531374/wish/1783950984 He lived around the 5th century BC in Ancient Greece. He proposed that matter was made up of small, indivisible particles, called atoms. He knew that if a stone was divided in half, the halves would have the same properties as the whole stone. If he kept cutting it in half, eventually, the stone would not be able to be cut in half anymore.
Fact: His travels are believed to have extended from Greece as far as India to the east and Ethiopia to the south.
]]> 2021-10-01 11:41:33 UTC https://padlet.com/jalende/q2j69zychh531374/wish/1783950984 Antoine Lavoisier jalende https://padlet.com/jalende/q2j69zychh531374/wish/1783952201 He lived in the 18th century in France. He established the law of conservation of mass, which means that after a chemical reaction that was identified by weight, it would be conserved by any reaction. He carefully measured the mass of reactants and products in different chemical reactions. It was the same. This showed that matter is not created or destroyed.
Fact: He was executed in 1794 using a guillotine.
]]> 2021-10-01 11:42:19 UTC https://padlet.com/jalende/q2j69zychh531374/wish/1783952201 John Dalton jalende https://padlet.com/jalende/q2j69zychh531374/wish/1783953105 He lived in the 18th and 19th centuries in Great Britain. He established many theories, like:
- all of the atoms of a specific element are identical in mass and properties.
- that chemical reactions are just a rearrangement of atoms. - he investigated the properties of compounds and how they are always made up of the same whole-number ratio.
Fact: After his studies of colour blindness, it was named Daltonism in his honour.
]]> 2021-10-01 11:42:56 UTC https://padlet.com/jalende/q2j69zychh531374/wish/1783953105 J.J. Thomson jalende https://padlet.com/jalende/q2j69zychh531374/wish/1783955469 He lived in the 19th and 20th centuries in Great Britain. He established that all atoms contain negatively charged subatomic particles which he called electrons. He said that the atom structure was like a plum pudding, which was a popular dessert in England at the time. The pudding would be the positively charged energy, and the plums would be the negatively charged electrons. He tested this by seeing through a tube with no gas that the electric charge was more invisible toward the end.
Fact: He was admitted into college at 14.
]]> 2021-10-01 11:44:37 UTC https://padlet.com/jalende/q2j69zychh531374/wish/1783955469 Ernest Rutherford jalende https://padlet.com/jalende/q2j69zychh531374/wish/1783957806 Ernest Rutherford lived in the 19th and 20th centuries in England. He contradicted Thomson’s plum pudding model, as he established that there was a positive charge in the middle of the atom, called the nucleus, which contains a lot of the atomic mass. He tested this nucleus by firing alpha particles into a sheet of thin gold. He got 3 results:
- some passed through the gold
- others changed direction after hitting the sheet
- some of them bounced back violently.
Fact: He had 11 siblings and was the 4th eldest.
]]> 2021-10-01 11:46:12 UTC https://padlet.com/jalende/q2j69zychh531374/wish/1783957806 Albert Einstein jalende https://padlet.com/jalende/q2j69zychh531374/wish/1783962623 Albert Einstein lived in the 19th and 20th centuries in Germany. He mathematically proved the existence of atoms and helped revolutionize all sciences that used statistical methods and probability. He tested this by observing groups of small molecules. Sometimes, they would move in the same way, but other times, they moved in different directions. Some atoms could be seen in the motion he called the “zig-zag” 
Fact: Even though Einstein is considered a smart scientist, it took him 3 years to start speaking.
]]> 2021-10-01 11:49:11 UTC https://padlet.com/jalende/q2j69zychh531374/wish/1783962623 Niels Bohr jalende https://padlet.com/jalende/q2j69zychh531374/wish/1783969207 Niels Bohr lived in the 19th and 20th centuries in Denmark. He came up with the “Planetary” model, which basically described that the nucleus stays in its place, meanwhile, the electrons, which he also discovered have constant energy, move around the nucleus like planets. But, electrons could only be seen in certain discrete energy levels.
Fact: His son Aage also won a Nobel Prize.
]]> 2021-10-01 11:53:34 UTC https://padlet.com/jalende/q2j69zychh531374/wish/1783969207 Louis de Broglie jalende https://padlet.com/jalende/q2j69zychh531374/wish/1783974470 Louis de Broglie, who lived in the 19th and 20th centuries in France. He introduced the idea that electrons could not only be described as particles but also as waves. It was substantiated by the way streams of electrons reflect against crystals and spread through thin metal foils. 
Fact: His validity paper was given to Einstein, and he approved it, so he got his PhD in Physics.
]]> 2021-10-01 11:56:52 UTC https://padlet.com/jalende/q2j69zychh531374/wish/1783974470 Erwin Schrodinger jalende https://padlet.com/jalende/q2j69zychh531374/wish/1783976147 Erwin Schrodinger lived in the 19th and 20th centuries in Austria. He contradicted Bohr’s theory somewhat, by saying the electrons actually move in more of a wave shape, but they are still moving around the nucleus. The experiment he did was called Schrodinger’s cat. A vial breaks if an atom decays inside of a box. Thus, the cat is both in alive and dead states.
Fact: A moon crater is named after him.
]]> 2021-10-01 11:58:00 UTC https://padlet.com/jalende/q2j69zychh531374/wish/1783976147 Werner Heisenberg jalende https://padlet.com/jalende/q2j69zychh531374/wish/1783977511 Werner Heisenberg lived in the 20th century in Germany. He studied quantum mechanics, discovering the uncertainty principle, which states that a particle's position and momentum cannot both be known exactly. He tried to observe the positions of electrons using a gamma-ray microscope, but a photon changed the momentum of the electron, moving it in an unknown way,
Fact: He was captured by American soldiers in WW2, and he was moved to England.
]]> 2021-10-01 11:58:56 UTC https://padlet.com/jalende/q2j69zychh531374/wish/1783977511 Sources: jalende https://padlet.com/jalende/q2j69zychh531374/wish/1783979729 Stubbings, Janice. History of Atomic Theory Chemistry Tutorial, https://www.ausetute.com.au/atomichist.html.  (Democritus)

“Antoine-Laurent Lavoisier.” Science History Institute, 15 Sep. 2021, https://www.sciencehistory.org/historical-profile/antoine-laurent-lavoisier.  (Lavoisier)


“Dalton's Atomic THEORY (ARTICLE).” Khan Academy, Khan Academy, https://www.khanacademy.org/science/chemistry/electronic-structure-of-atoms/history-of-atomic-structure/a/daltons-atomic-theory-version-2.  (Dalton)


“The Nobel Prize in Physics 1906.” NobelPrize.org, https://www.nobelprize.org/prizes/physics/1906/thomson/biographical/.  (Thomson)


“Ernest Rutherford.” Science History Institute, 11 Jan. 2018, https://www.sciencehistory.org/historical-profile/ernest-rutherford.  (Rutherford)


Bowersox, Paul. “Albert Einstein and the Most Elemental Atomic Theory.” ANS, https://www.ans.org/news/article-969/albert-einstein-and-the-most-elemental-atomic-theory/. (Einstein)


Stubbings, Janice. History of Atomic Theory Chemistry Tutorial, https://www.ausetute.com.au/atomichist.html. (Bohr)  


“The Nobel Prize in PHYSICS 1929.” NobelPrize.org, https://www.nobelprize.org/prizes/physics/1929/broglie/facts/. (de Broglie)


Stubbings, Janice. History of Atomic Theory Chemistry Tutorial, https://www.ausetute.com.au/atomichist.html. (Schrodinger)

“The Nobel Prize in Physics 1932.” NobelPrize.org, https://www.nobelprize.org/prizes/physics/1932/heisenberg/biographical/. (Heisenberg)  
]]> 2021-10-01 12:00:23 UTC https://padlet.com/jalende/q2j69zychh531374/wish/1783979729