Saturday, July 28, 2007

History of Atom Models

If we talk about the history of atom, we can separate this into two periode, classic and modern. At the classic periode we find Democritus and Aristoteles. Aristoteles think that a matter have discontinue properties. If us divide a matter, hence we can continue the dividing of infinite. While according to Aristoteles, we will until in the situation that matter is other impartible. The impartible matter at later was called atom by Dalton.

The next person who released atom model theory is Dalton. He say that atom like ball of bilyard. One otem and another have different in form and properties. Chemical reactions are rearrangements of atoms (mass is conserved). Then Thomson continue idea concerning atom with the theory of that atom is positive electricity particle and electron spread over in it.

At next period, Rutherford release Solar System Model. Having taken steps attempt shot off alpha rays to a gold plate, he find that shot off alpha rays continued, to be turned and re-bounced. From this experiment result Rutherford trigger the idea of concerning atomic nucleus. Electron reside in around nucleus like our solar system with atomic nucleus as his center.

Next model of the atom conceived by Danish physicist Niels Bohr in 1913. It assumes that the following rules govern the behaviour of electrons: (1) electrons revolve in orbits of specific radius around the nucleus without emitting radiation; (2) within each orbit, each electron has a fixed amount of energy; electrons in orbits farther away from the nucleus have greater energies; (3) an electron may ‘jump’ from one orbit of high energy to another of lower energy causing the energy difference to be emitted as a photon of electromagnetic radiation such as light; (4) an electron may absorb a photon of radiation and jump from a lower-energy orbit to a higher-energy one.(http://encyclopedia.farlex.com)

Electrons are in constant motion around the nucleus, protons and neutrons jiggle within the nucleus, and quarks jiggle within the protons and neutrons.

This picture is quite distorted. If we drew the atom to scale and made protons and neutrons a centimeter in diameter, then the electrons and quarks would be less than the diameter of a hair and the entire atom's diameter would be greater than the length of thirty football fields! 99.999999999999% of an atom's volume is just empty space!(http://particleadventure.org)

I have no more idea to explain you about this topic. If you have a good knowledge about history of atoms theory, I hope you can tell me.

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