Atomic Theory Essay, Research Paper

In ancient Greek the word atom meant the smallest indivisible atom that could be conceived. The atom was thought of as indestructible ; in fact, the Greek word for atom means & # 8220 ; non divisible. & # 8221 ; Knowledge about the size and do up of the atom grew really easy as scientific theory progressed. What we know/theorize about the atom now began with a nucleus theory devised by Democrotus, a Grecian philosopher who proposed that affair consisted of assorted types of bantam distinct atoms and that the belongingss of affair were

determined by the belongingss of these atoms. This nucleus theory was so modified and altered over old ages by Dalton, Thompson, Rutherford, Bhor, and Chadwick. The atoms original construction was simple, but as more and more research was done the atom became more complex and puzzling.

Our first helper of atomic theory was John Dalton, a adult male subsequently nick-named the & # 8220 ; Father of atomic theory & # 8221 ; for his part of many theories and Torahs to modern atomic theory. His theories answered many inquiries of disbelieving scientists: elements combine with one another to organize chemical compounds and the atom doesn & # 8217 ; t alteration, atoms link together in definite proportions, all atoms of any component are all the same, the jurisprudence of multiple proportions which states that a given mass of one component can unite with assorted multitudes of another component ( or elements ) but ever in little whole figure ratios, and the jurisprudence of preservation of affair, affair can neither be created or destroyed, but it can alter signifier.

One of the following most accepted people involved in the patterned advance of atomic theory was J.J. Thompson. Thompson had researched the work of William Crookes whose research concluded that cathode beams were deflected by magnetic Fieldss. Thompson elaborated on this decision and found that cathode beams were besides deflected by an electric field. With much experimentation Thompson theorized that although the atom was made up of little atoms it was non the same indestructible theoretical account proposed by Dalton. A adult male named Milikin determined the mass of an negatron to be 0 amu and the comparative charge to be negative 1. With the find of these negatrons by Thompson and the find of protons several old ages subsequently Thompson was able to invent a new theoretical account of the atom. Thompson stated that protons and negatrons were equally distributed throughout the atom. This theoretical account was labeled the & # 8220 ; plum-pudding theoretical account & # 8221 ; . Thompson described the atom as a icky mass of positively charged atoms ( protons ) with raisins ( negatrons ) embedded all around it.

Ernest Rutherford was a major subscriber to the atomic theoretical account because he proved that although Dalton and Thompson were partly right there was still a defect in both of their theoretical accounts of the atom. Rutherford devised an experiment to either prove or confute Dalton & # 8217 ; s theoretical account and or Thompson & # 8217 ; s theoretical account. Rutherford and his helpers set a piece of radioactive stuff in a lead box with a little hole in one side to direct the alpha particles towards the gold foil, which was surrounded by Zn sulphide screens. The Zn screens showed flashes of visible radiation where the alpha atoms were traveling to travel, directly through ( Thompson & # 8217 ; s theoretical account ) or straight back ( Dalton & # 8217 ; s theoretical account ) . To his amazement atoms were through, came back, and some besides were deflected to the sides of the gold foil. He proved that Dalton and Thompson were wrong and the atom consisted largely of infinite. At the centre of this infinite is a really little nucleus, called the karyon, which can warrant the deflected atoms. Rutherford established that the mass of the atom is concentrated in its karyon

. He found that an negatron is 1/1836 the mass of a proton and he besides proposed that negatrons travel in orbits around the karyon.

With all of these changes to the theory of an atom a few, five to be exact, jobs arose. One of the major jobs was the size of an atom. If each negatron had its ain orbital and the atom had 23 negatrons so the atom would be tremendous. Another job with the orbital of an negatron was that no energy could be observed by the negatron orbit decay. Next, if the centre of an atom was composed of protons ( + ) and the negatrons ( – ) orbited this positive nucleus why didn & # 8217 ; t the negatrons crash into the protons, doing an extremist violet calamity. Besides, if the nucleus was composed of merely positive protons and opposite charges repel so how did the protons stay together. And the concluding job, the atom didn & # 8217 ; t weigh plenty. When scientists added the weight of the negatrons and the weight of the protons and subtracted that from the overall weight of the atom there was a balance. Something had to be losing from the theoretical account of an atom to do up for the weight difference. The replies to these inquiries came from the following large subscribers to this theory, Niles Bohr and Chadwick.

Niles Bohr developed a theory known as the Bohr theory of the atom. He assumed that negatrons are arranged in definite energy degrees, or quantum degrees, at a specific distance from the karyon. The agreement of these negatrons is called the negatron constellation. There are seven degrees, which were derived from the seven colourss he saw, each of which has a specific figure of negatrons that it has capacity for. The first degree can merely suit two negatrons, the 2nd can keep up to eight negatrons, the 3rd can keep up to eight-teen, and so on. If an atom had four negatrons you wouldn & # 8217 ; t happen two in the first, one in the 2nd, and one in the 6th. Electrons ever occupy the lowest energy degrees foremost. Electrons in a & # 8220 ; land province & # 8221 ; are in their regular energy degree and give off no energy ; nevertheless, if an negatron is in an & # 8220 ; excited province & # 8221 ; it sends energy in quantum packages ( photons ) and visible radiation is observes. When aroused negatrons jump up a degree they give off light energy: nevertheless, they can ne’er travel down a degree, energy can ne’er be lost merely gained.

Chadwick discovered the last piece of information about the atom. In 1932, through mass spectronomy, he discovered a heavy impersonal atom with the mass of a proton. He called it a neutron. This answered the few staying inquiry about the atom. There was no longer a losing portion because the neutron made up for the original weight loss. And it answered the inquiry about how the protons stayed together. The neutrons had a soothing consequence on the protons. Between every two protons lies a neutron, which attracted the protons, which made the nucleus really condensed.

With the last find, of the neutron, scientists were able to finish the theoretical account of the atom. The completed theoretical account that they came up with is the theoretical account that pupils now learn about in school. These scientists did precisely what scientists are supposed to make: trial, experiment, and answer inquiries. Because of the old ages of survey they did we now have a strong thought of what an atom is and what its constituents are. A theory ne’er becomes fact until all of the bugs are wiped out, if this is true so this atomic theory is good on its manner to going the facts about atoms.

Bibliography

Beginnings:

Textbook: Chemistry: The Study Of Matter, Simon and Schuster, right of first publication 1992

Internet Beginning: hypertext transfer protocol: //encarta.msn.com/find/Concise.asp? ti=03E68000