History of the Atom

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  • Topic: Atom, Ernest Rutherford, Electron
  • Pages : 6 (2172 words )
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  • Published : October 5, 2010
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* Democritus
Democritus had a theory that all matters are composed with tiny unbreakable particles called atom. He tried to break down matters into smallest particles. His model was that the matter would stop splitting in halves when it reaches its smallest matter. He called that an atom. * John Dalton

In 1803, John Dalton proposed a theory. The theory had 4 parts into it. 1. Elements are made of identical atoms.
2. Atoms of different elements are physically different
3. Compounds are formed by a combination of two or more different kinds of atoms. 4. A chemical reaction is arrangement of atoms.
Dalton formed different compounds from its elements. Adding extra of one reactant made no different. He tried variety of different combinations to form a new compound. The ratio that he was combining was inaccurate, but for the time back then, his experiment was closer to the modern technology.

* JJ Thomson
He tested the origin and properties of cathode ray using a cathode ray tube. And his observation was with electricity, a metal plate produces a cathode ray. The model is called plum pudding model. Because it has negative charged particles named electrons inside atom. They can be removed or added to form an iron.

* Loard Ernest Rutherford
* Lord Ernest Rutherford came from Nelson New Zealand. In 1911, his observation was the atom should be, if the plum theory was correct, solid pudding, small particles might not pass through the pudding. For experiment, Alpha particles were shot through the gold and beamed out. Almost all alpha particles passed through a thin sheet of gold but some were deflected or bounced back.

* Neil bohr
Neils Bohr came up with a observation that, since + and – charges electrons on the outside should come crashing into the nucleus cancelling both out. His experiment involved studying light coming from atoms that are ‘excited’ by electricity or flame. The light is made of distinct colour liens called an emission spectrum. Electrons were absorbing and releasing specific of energy. The theory was electrons could be found in fixed levels. -James Chadwick

James Chadwick predicted that atoms are heavier than electrons and protons. The experiment was looking at beryllium when it hit alpha particles- which caused a neutral beam to be emitted. His theory was that the nucleus of an atom contains neutrons.

The History of the Atom

In many ways our learning of the atom has influenced human’s knowledge. In addition to that, the history of the atom, and how it’s been used has equally affected human’s knowledge. This knowledge of the atom we have acquired can help us improve life from day to day and explain the phenomenon known as the Theory of Everything. The founder of the atom was Democritus (460-370B.C.), an ancient Greek philosopher whose goal in life was to explain the natural world. It was he who made the basis for which the foundation of the atom was created. This foundation was his theory that all tangible objects in the world had a “primary matter” which was used in different variations to make everything that surrounds us. He also discovered that this “primary matter”, or atom, as he first established, only had three main differences; he discovered shape, size, and weight differed between atoms. All of the work that Democritus did is seen as a more or less basic description of an atom. Despite his uncanny accuracy of the atom with such limited technology, and without being able to do any experiments, the atom was ignored for the subsequent 2000 years. The next essential scientist to be recorded as an innovator in history for the atom was John Dalton(1766-1844). “Dalton's theory can be summarized as follows: 1. Matter is composed of small particles called atoms.

2. All atoms of an element are identical, but are different from those of any other element. 3. During chemical reactions, atoms are neither created nor destroyed, but are...
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