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465
Democritus's Theory
The first person to come up with the idea of an atom was Democritus. He was an Acient Greek philosopherwho was born in Abdera, Thrace in Greece. Forever he will be known at the one who formulated the atomic theory. His theory was that an atom looked the the picture you see here. He believed that matter couldn't be made into smaller particles. He was right that there are atoms but he didn't know everything about them. -
Period: 465 to
Atomic Theory Timeline
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John Dalton's Theory
John Dalton was the next person to have a new theory about the atoms. He was born on September 6, 1766 in Eaglesfield, Cumberland England and he died on July 27 1844. He lived to be only 77 but he did some great things in his lifetime. His atomic theory was that all matter is made of atoms, atoms are indestructible, all atoms are identical in mass and properties in one element, and that compounds are formed by a combination of two or more different kinds of atoms. -
Sir William Crookes' Atomic Theory
Sir William Crookes was born June 17, 1837 in London, England and he died on April 4, 1919. He is the man who discovered the electron that is inside of atoms. He discovered them by reconstructing the Cathode Ray. He put black vanes on one side and silver on the other, which caused the vacuum tube to spin when it hit light. Since the Cathode Ray had already been built, he had to call it something else, so today it is called the Crooke's Tube. -
J. J. Thomson's Atomic Theory
Joseph John Thomson, or J.J., was born December 18, 1856 and he died on August 30, 1940. He is the first man who discovered electrons that are inside atoms. His atom model was known as "The Plum Pudding Model of an Atom". His research proved that atoms are made of smaller particles, and he proved this theory using the cathode ray tube. -
Ernest Rutherford's Atomic Theory
Ernest Rutherford was born on August 30, 1871 and he died October 19, 1937 at the age of 66. He discovered protons and the nucleus of atoms in 1911, and he named them. He believed there were protons, electrons, and a nucleus in an atom but there was also a lot of empty space. He made a great breakthrough in the atomic theory and helped us understand atoms better. -
Niels Bohr's Atomic Theory
Niels Bohr was born October 17, 1885 in Copenhagen, Denmark and he died on November 18, 1962 at age 77. He figured out that electrons revolve around the nucleus of an atom in layers he called shells. Bohr's model was basically an improved version of Ernest Rutherford's model, but it was a great discovery still and an addition to the atomic theory. -
Modern Atomic Theory
Many people have contributed to the atomic theory to what it is today. Scientists have discovered, protons, neutrons, electrons, shells, valence electrons, and the nucleus in a single atom! Our technology and ways to research have gotten a lot better over the years and because of research on the atomic theory many new elements have been discovered, and many more things will be discovered. -
Aristotle's Atomic Theory
Aristotle was born in 384 B.C. and died in 322 B.C. He believed that everything was made of either earth, water, wind, or fire. He did not believe that there were atoms that made up everything, so him and Democritus disagreed. Everyone in that time believed Aristotle because he was a very smart and respected man, so that was the common belief. It wasn't until about 2,000 years later that scientists started making a major breakthrough with the atomic theory.
