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200
Kanada
• It is Estimated Kanada lived in the 2nd century bc but is also said that he may of lived in the 6th century bc. • Had a theory that the Atom was an indestructible particle of matter.• This is where the word Atom first originated. -
460
Democritus
• Democritus was born in 460bc in Abdera, Greece. He lived to the age of 90, passing in the year 370bc.• He did not originally come up with the Atomic theory but soon adopted it from his mentor Leuscippus.• The Atomic theory stated that “The universe is composed of two elements: the atoms and the void in which they exist and move.” -
460
Democritus
• Democritus emphasized that Atoms were Invisible, could not be destroyed, differed in shapes, sizes and temperature, and were always moving.• He also stated that Atoms were tiny quantities of matter. -
Robert Boyle
• Robert Boyle was born on January 25th, 1627 in Ireland. He died on the 30th of December 1691 in London. • Robert Boyle took Aristotle’s conception of the four elements, and replaced it with a modern idea that an element is a substance that cannot be separated into simpler components by chemical.• With his studies, he created the foundations for modern chemistry. -
Antoine Lavoisier
• Antoine Lavoisier was born on the 26th of August 1743 in Paris. He died on the 8th of May 1794 in Place de la Concorde. • He discovered that matter may change it’s shape or form but it’s mass always remains the same. • He recognized and named hydrogen and oxygen. • He wrote the first extensive list of elements.• He helped create the Metric system and put an end to the phlogiston theory. • He also helped to reform chemical nomenclature. -
John Dalton
• John Dalton was born in September the 6th 1766 in Eaglesfield England. He died on the 27th of July 1844 in Manchester, England. • John Dalton was the creator of the Daltons law and also created a system of symbols to represent atoms of different elements. • His theory was basically a more modern and in depth version of Democritus’s and a basis for other scientist to explain the evidence about atoms. -
Robert Brown
• Robert Brown was born on the 21st of December 1773 in Montrose, Scotland. He died on the 10th of June 1858 in London.• He did a test through a microscope, which was putting particles found in pollen grains, in water, noting that the particles moved through the water but was not able to determine how this motion occurred. -
Robert Brown
• Many decades later, Albert Einstein published a paper in 1905 explaining precisely how the motion Robert Brown had seen was a result of the pollen being moved by individual molecules of water. • This confirmed that atoms and molecules actually exists, and was further verified by Jean Perrin in 1908. -
William Crookes
• William Crookes was born on the 17th of June 1832 in London. He died on April the 4th, 1919 in London. • Discovered that Cathode rays travel in straight lines from the cathode, cause’s glass to fluoresce, Send a negative charge to the objects they strike, and is reflected by electric fields and magnets suggesting a negative charge, that they have mass because pinwheels span when they were in the cathode path. -
Dmitri Mendeleev
• Dmitri Mendeleev was born on the 8th of February 1834 in Tobolsk. He died on the 2nd of February 1907 in Saint Petersburg. • Created the Periodic Law. • Arranged elements into 7 categories with similar properties• He discovered that the properties of the elements “Were periodic functions of their atomic weights”. -
J.J Thomson
Joseph John Thompson was Born on the 18th of December 1856 in Cheetham hill. Died on the 30th of August, 1940 In Cambridge.• Found the particle now known as electron.• Made a formula to calculate the mass ratio of the electron. • Discovered that the electron is a component of all matter. -
Ernest Rutherford
• Ernest Rutherford was born on the 30th of August 1871 in Brightwater, New Zealand. He died on the 19th of October 1937 in Cambridge. • Him and Hans Geiger did the "Golden Foil Experiment” Discovering the Atomic Nucleus. -
Ernest Rutherford
• He had theory that the atom included a central positive nucleus surrounded by negative orbiting electrons. This suggested that most of the mass was contained with the small nucleus and that the rest was mostly empty space. This was all discovered because of the “Golden Foil Experiment”. -
Otto Hahn
• Otto Hahn was born on the 8th of March 1879 in Frankfurt. He Died on the 28th of July 1968 in Gottingen.• Discovered a way to make Atoms smaller and to still not destroy them. • He discovered this by bombarding Uranium with Neutrons, which makes smaller nuclei.• He also discovered another way to split the atom. -
Hans Geiger
• Hans Geiger was born on the 30th of September 1882 in Neustadt an der Weinstrabe. He died on the 24th of September 1945, Potsdam. • Hans Geiger and Ernest Marsden did the “Gold Foil Experiment” Resulting in the Discovery of the Atomic Nucleus. • He also was co-inventor of the Geiger Counter which Detects Radioactive Particles. -
Niels Bohr
• Niels Bohr was born on the 7th of October 1885 in Copenhagen, Denmark. He died on the 18th of November 1962 in Copenhagen. • Bohr Developed a theory that electrons travelled in stationary orbits defined by their angular momentum. He compared this to the planets orbiting the sun. • This theory was used in Ernest Rutherford’s atomic structure.• This then lead to the ability to calculate energy levels. -
James Chadwick
• James Chadwick was born on the 20th of October 1891 in Cheshire, England. He died on the 24th of July 1974 in Cambridge. • He discovered the particle within the atom that we know now as the neutron because of its lack of electric charge. • This was a very significant find and was a key foundation for the further research into the atom. -
Aristotle
• Aristotle lived from 384bc – 322bc in Greece. • He Strongly Disagreed with Democritus and his theory for most of his theories were based more on thought then science. • He believed everything was made of the four elements, Fire, Water, Earth, Air.
