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Period: 350 to
The Evolution Of The Atomic Thoery
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425
Democritus
Democritus lived in the time period of around 425 BC. He was the first man that thought that atoms were real. Democritus thought that atoms are small hard particles, made of a single material formed into different shapes and sizes, they are always moving and they form different materials by joining together. No one believed him because he couldn't find any evidence to prove his theory. Democritus’s theories were brought back after many years. -
425
Aristotle
Aristotle lived also in the time period of around 350 BC. He was a philosopher. He believed that there was only 5 elements. Those 5 elements were water, fire, earth, wind and ether (the air above the clouds). Everyone beleived Aristotle's theory. -
John Dalton
John Dalton brought back Democritus’s theory of atoms. John Dalton lived in 1808 in Cambridge, England. He was a scientist. He did many experiments to prove that elements can join together and create new substances. Dalton came up with four new theories about atoms. The theories were all substances are made up of atoms which are small particles that cannot be created, divided or destroyed, atoms of the same element are exactly alike and atoms of different elements are different, atoms join with -
Sir William Cookes
Sir William Crookes was a chemist during London, England during 1835. He discovered in an experiment that discovered that a glass tube with electrodes connected to either side of the glass tube and a battery. This experiment showed Crookes how electrons traveled. This experiment was also called the vacuum tube experiment. -
Mendeleev
Dmitri Mendeleev was a Chemist in Russia during 1896. He decided that he was going to arrange the elements. This was the beginning of the modern periodic table. Mendeleev also started the octet rule. -
J.J. Thomson
J.J. Thomson was a physicist from England in the late 1800s to the early 1900s. Thomson discovered more about the particles electrons. He brought back Crookes vacuum tube experiment. Thomson’s experiment was different than Crookes. He used a different type of tube. This made no difference. Thomson made the diagram called the Plum-Pudding model or nowadays it is called the Chocolate Ice Cream Model. -
Erwin Schrödinger
Erwin Schrödinger was a physicist from Vienna, Austria-Hungary during 1900. Schrödinger created The Cloud Model. The cloud model was a more modern look to it. -
Ernest Rutherford
Ernest Rutherford was a chemist and a physicist. in 1911 from New Zealand. Rutherford was Thomson’s student. Rutherford did an experiment called the Gold Foil experiment. He thought that all of the particles would go straight through the gold foil barrier. Actually some of the particles did not go straight through the gold foil barrier. Most of the particles did though. -
Niels Bohr
Niels Bohr was a physicist from Denmark in 1913. Bohr created the planetary model. Bohr’s model is still used today. His model shows what the shape of an atom is. His model shows the movement of the electrons around the outside of the atom in the electron cloud. -
James Chadwick
James Chadwick was a physicist from Cambridge, England during 1932. Chadwick in 1932 discovered neutrons. Neutrons are the nutreual part in the nucleus. Chadwick was the apprentice of Rutherford. In 1935 Chadwick earned the Nobel Prize in science.
