Neils Bohr and Atomic Theory
In ancient Greek the word atom meant the smallest indivisible particle that could be conceived. The atom was thought of as indestructible; in fact, the Greek word for atom means "not divisible." Knowledge about the size and make up of the atom grew very slowly as scientific theory progressed. What we know/theorize about the atom now began with a core theory devised by Democrotus, a Greek philosopher who proposed that matter consisted of various types of tiny discrete particles and that the properties of matter were determined by the properties of these particles. This core theory was then modified and altered over years by Dalton, Thompson, Rutherford, Bhor, and Chadwick. The atoms original structure was simple, but as more and more research was done the atom became more complex and puzzling The five atomic theories of the past two centuries represent the sudden advancement of science in modern times. Beginning with a basic theory on the behavior of atoms to the current model, some changes have been made, and some ideas are still the same. Ancient Greek philosophers believed that everything was made up of invisible particles called atoms.
With all of these alterations to the theory of an atom a few, five to be exact, problems still arose. One of the major problems was the size of an atom. If each electron had its own orbital and the atom had 23 electrons then the atom would be enormous. Another problem with the orbital of an electron was that no energy could be observed by the electron orbit decay. Next, if the center of an atom was composed of protons (+) and the electrons (-) orbited this positive core why didn't the electrons crash into the protons, causing an ultra violet catastrophe. Also, if the core was composed of just positive protons and opposite charges repel then how did the protons stay together. And the final problem, the atom didn't weigh enough. When scientists added the weight of the electrons and the weight of the protons and subtracted that from the overall weight of the atom there was a remainder. Something had to be missing from the model of an atom to make up for the weight difference. 2. All atoms of the same element are exactly alike; in particular, they The answer to these questions came along with the work of Neils Bohr. Danish physicist Neils Bohr used new knowledge about the radiation emitted from atoms to develop a model of the atom significantly different from Rutherford's model. Neils Bohr developed a theory known as the Bohr theory of the atom. He assumed that electrons are arranged in definite energy levels, or quantum levels, at a specific distance from the nucleus. The arrangement of these electrons is called the electron configuration. It is much like that of our planetary system. All of Dalton's ideas account for the laws of definite and multiple proportions and the law of conservation of mass. Some of Dalton's points are still thought to be true, but over time this original theory has been modified. John Dalton was the first scientist to compose a theory of matter based on atoms. Dalton's atomic theory is based
Some common words found in the essay are:
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Approximate Word count = 1312
Approximate Pages = 5 (250 words per page double spaced)
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