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200
Democritus(440 BC)
Democritus was born in northern Greece, in Abdera and wrote language, math, and physics. Democritus thought that the world was made of an infinite number of atoms. Everything was made of differnt atoms with differnt sizes and the feeling of sensation was actually touching atoms. Democritus thought that since our world came from a combonation of atoms and everything in the world is made of atoms there must be many other worlds besides our own. -
200
Aristotle
Aristotle was one of the most famous philosiphers in Greece. His Atomic theory was that all matter was made of either earth, wind, fire, or water. Also the matter had aspects of dryness, wetness, coldness, or hotness. Aristolte thought that the elements were harmony or conflict and it made a natural peace between all elements. -
Dalton
John Dalton had a theory in 1803 that paved the way for modern chemistry. The theory stated that chemical elements are made of their own types of atoms and that a substance's fixed weight always combined with another object's fixed weight make a compound. -
Thomson
In 1895 Joseph Thomson started to look into what type of rays were in a glass test tube that had electricity running into it. Many people called them cathode rays since they came from the cathode. But Thomson thought they were made of matter particles. Thomson built a contraption that had electrical and magnet fields and ran electricity through the it. Thomson controled the rays and found they were negative, since they stayed negative he thought they were part of atoms. They were electrons. -
Rutherford (1909)
In 1909 Sir Ernest Rutherford tested a pervious theory about atoms. Rutherford shot positively charged particles at a gold coated metal sheet. Once the particles hit the sheet the gold came off and glowed, this showed Rutherford where the particles had hit the sheet. Most of them went right through the sheet, but some of them went to the side after going through and some were deflected. This meant that there was empty space in atoms and that they are very densely packed. -
Rutherford(1911)
In 1911, Ernest Rutherford created a new theory of what atoms look like. The new model has a nucleus in the center, a large particle, and smaller, fast particles circling it called electrons. The area that the electrons are in is called the electron cloud. -
Bohr
In 1913, Niels Bohr came out with a new model of an atom. This atom had several paths for electrons to follow instead of one, and a smaller nucleus made from protons and neutrons. -
Schrodinger and Heisenberg
The scientist Werner Heisenberg, in 1923 updated the ideas made by Schrodinger and a few others. This equation is the way to understand atoms today. Solving the equation predicts the reactivities and principles of molecules, it is extremly hard to solve even with the simplest of atoms.
