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Period: to
famous experiments/other historic events
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A new element
Joseph Priestly in 1774, discovered oxygen. He, at the time called it dephlogisticated air. He did it by heating up materials and creating vapours.
It was later named oxygen by Antoine Lavoisier. -
Fire mysteries answered
Antoine Lavoisier was a french chemist who discovered that mass is conserved in a chemical reaction. He called it the conservation of matter theory and explained the mysteries of fire. -
Useful Theory
John Dalton developed the first effective and useful atomic theory of matter. -
Periodic table
Lothar Meyer published a periodic table which described the placement of 28 elements. Meyer's periodic table ordered the elements into groups arranged in order of their atomic weights. His periodic table arranged the elements into 6 families according to their valence, which was the first attempt to classify the elements according to this property. This graph is a later version. -
improved theory
Dmitri Ivanovich Mendeleev created the first plausibe periodic table (as seen on the left) also improving on Dalton's theory. -
failed experiments\Thomson
J.J. Thomson sugested that atoms have particles. He promoted the idea that cathode rays are really streams of very small pieces of atoms. He tried to prove this. In the 1890s, thomson built a cathode ray tube. He wanted to see if, by bending the rays with a magnet, he could seperate the charges from the ray. As Thomson saw, the negative charge and the cathode rays must somehow be stuck together. You cannot seperate the charge from the rays. He decided he'll take a different approach. -
Rutherford discovery
Ernest Rutherford discovers alpha and beta raiation.
Rutherford used an electrometer to measure an electric current created by the radiation rather than the more crude technique of photograhic plates. -
J.J. Thomson Info
J.J. Thomson was the first to measure the electron and he developed the plum-pudding model of the atom. He describes the atom as a slightly positive sphere with small electrons inside. -
First man-made flight
The Wright brothers build the first flyable aircraft, airplane, etc. -
Einstein theory
Albert Einstein proposed the quantum of light in which he states that light behaves like a particle but also has a wave nature, giving it a dual nature. It stated the equal of energy and mass
through the theory of special relativity. -
Rutherford's award
Rutherford gets a nobel prize in chemistry "for his investigations into the disintegration of the elements, and the chemistry of radioactive substances". -
Rutherford experiment
Ernest Rutherford used a small, dense, positively-charged nucleus as the result of the alpha particle scattering gold foil experiment. -
world war 1
The great war starts. The fighting lasted until 1918. -
To Bohr's hard work
In 1922, Niels Bohr won the noble prize for physics mainly for his work on atomic structure. -
The neutron
Rutherford's assistant, James Chadwick discovers the neutron.
Chadwick put a piece of beryllium in a vacuum chamber with some polonium. The polonium emitted alpha rays, which struck the beryllium. When struck, the beryllium emitted the mysterious neutral rays. In the path of the rays, Chadwick put a target. When the rays hit the target, they knocked atoms out of it. The atoms, which became electrically charged in the collision, flew into a detector. Then he found out it was a neutron. -
Rutherford's theory comes true
Rutherford always knew that there was a neutron to go with the proton and electron. His assistant James Chadwick added and improved to Rutherford's theory by actually discovering the neutron. -
second world war
World war 2 begins. Ended 1945. -
Manhattan project
The Manhattan project was started. It was the invention of the atomic bomb that was later dropped on Hiroshima and then Nagasaki, Japan. That was the first time they learned to control the atom and use it. Unfortuantly they used it to kill. Over 200,000 people were killed.
Albert Einstein was part of the Manhattan project. -
Man-made elements?
Glenn Seaborg succeeded in making man-made elements.
Seaborgium was named in his honour, making him the only person for whom a chemical element was named during his lifetime. -
Uranium exp.
Laser separation of uranium isotopes created. -
Periodic table now
Since the earth was created there were elements. Just since the 1700s and up people have created the periodic table. Just now, there are more elements discovered than before. The latest periodic table is quite a difference from Dmitri Mendeleev's version in the 1700s or even Lothar Meyer's version back in the 1860s. I am sure that there are a lot more elements still to be found.
