1.1+Theories

 Atomic theories​ ​​​The actual atomic theory was built principaly by the antique greek philosophers : __Empedocles__: saids that all the matter was composed by the 4 elements. __Democrit of Abdera__: afirmates that all the forms of the matter, was divisible until a point in invisible particles that he calls atoms, saids to that that the particles were in constant movement, and can conbinate between them in different ways. __Aristoteles__:opposed to Democrit an suppor the Empedocles theory.

With those bases then came the modern atomic theories and then the quantum atom model.

After those greeks theories came the true theories and the true definitions of element and compound. Element: basic sustance that are composed by the same atom class. Compounds: a sustance that are composed by more than once atom class.

With those definitions the modern atomic theory was made, those definitions were made by Boyle,Dalton, Thomson and ernest Rutherford.(are explained dawn)by other classmates.

After that came the quantum atom model that were made by Broglie, heisemberg and shrodinger.(that theorie are explained dawn to by other classmates)

That image show how is the atom evolution in modern atomic thoriemedia type="youtube" key="x_tNzeouHC4" height="235" width="275" align="left" and the videos show how the quantum atom midel works.

the information was taken from:portal de la ciencia 7 editorial norma the information was mine textual production. Edwin Bedoya Cardona

=Atomic Theory = A theory of the structure and behavior of atoms has taken more than two millenia to evolve, from the abstract musings of ancient Greek philosophers to the high-tech experiments of modern scientists. However, prior to the scientific revolution and the development of the scientific method starting in the 16th century, ideas about the atom were mainly speculative. It wasn't until the very end of the 19th century that technology became advanced enough to allow scientists a glimpse of the atom's constituent parts: the electron, nucleus, proton, and neutron.

Greek Origins While the idea of the atom was supported by some later Greek philosophers, it was fiercely attacked by others, including Aristotle, who argued against the existence of such particles. During the Middle Ages in Europe, Roman Catholic theologians were heavily influenced by Aristotle's ideas, and so atomic philosophy was largely dismissed for centuries. However, the Greeks' conception of the atom survived, both in Aristotle's works (his arguments against) and in another classical work by the Roman author Lucretius, //De rerum natura// (“On the Nature of Things”), which was rediscovered in Europe at the start of the Renaissance.

Modern Development
Modern atomic theory is generally said to begin with John Dalton, an English chemist and meteorologist who in 1808 published a book on the atmosphere and the behavior of gases that was entitled //A New System of Chemical Philosophy.// Dalton's theory of atoms rested on four basic ideas: chemical elements were composed of atoms; the atoms of an element were identical in weight; the atoms of different elements had different weights; and atoms combined only in small whole-number ratios, such as 1:1, 1:2, 2:1, 2:3, to form compounds. Not all of these ideas were new; the Greeks had already introduced the idea that elements were composed of atoms and that atoms of different elements had different physical properties. Dalton's particular contribution, which distinguished his work from what had been done before, was his method for actually determining atomic weight. In an essay published in 1805, Dalton had included a list of atomic weights for 21 elements. Dalton was also the first to propose standard symbols for the elements.

Subatomic Structure Actually, what Thomson discovered was that cathode rays were streams of negatively charged particles with a mass about 1,000 times smaller than a hydrogen atom. He claimed that these particles, which he called “corpuscles,” were the things that atoms were made from. The term “electron” predated Thomson's discovery—a few years earlier Irish physicist G. J. Stoney had proposed that electricity was made of negative particles called “electrons,” and scientists had adopted the word to refer to anything with an electric charge. However, Thomson, who was a physicist at Cambridge University, was the first to suggest that these particles were a building block of the atom.

[Bohr : in 1913 he descovered the planetary model where the electron move around the atom in circular orbits, the electrons have determinated orbits.​ ​ external image atomo2.jpg​ ​Broglie : he descovered the behavior dual of atoms : the atom can be a wave or a particle. external image teoria_atomica10.jpgheisenberg : he said that the electron move free on a region of the space and is imposible to know his speed and position .schrodinger : he make an matematic ecuation to determinate the posibility to find a electron in a region near to the nucleus.all the theories external image f525burns.JPGpedro juan mejia aguilarportal de la ciencia 7 23 febrero 2010 none GuardarPrevisualizarText Editor html|http://www.infoplease.com/ipa/A0905226.]
 * ====== N. Bohr : in 1913 he descovered the planetary model where the electron move around the atom in circular orbits, the electrons have determinated orbits. ======

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 Broglie : he descovered the behavior dual of atoms : the atom can be a wave or a particle. || || || external image teoria_atomica10.jpg || ======

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 heisenberg : he said that the electron move free on a region of the space and is imposible to know his speed and position. ======

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 schrodinger : he make an matematic ecuation to determinate the posibility to find a electron in a region near to the nucleus. ======

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 23 febrero 2010
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= ATOMS THEORIES = = = THERE ARE MANY THEORIES,THAT REPRESENT THE ATOM.

**JHON DALTON THEORY:** HE FORMULED THE THEORY IN 1810. HE SAID THAT THE ELEMENTS ARE FORMED BY PARTICLES. ​ ​ ** J.J THOMPSON THEORY: ** HE SAID THAT THE ELECTRONS HAVE POSITIVE CHARGE. HE SAID THAT THE ATOM IS UNDIVISIBLE. HE IDENTIFY THE ELECTRON.


 * ERNEST RUTHERFORD THORY: ​​** HE IDENTIFY THE RAYS THAT CAUSE RADIOACTIVE SUSTANCES. HE DESCOBER THE ELECTRON IN 1911. AND HE DESCOBER THE PROTON.



BOHR THEORY: HE FORMULED THE THEORY IN 1913. HE MADE THE PLANETARIUM MODEL. HE SAID THAT THE THEORY OF ERNEST WAS WRONG BEACAUSE THE ELECTRONS COULD CRASH WITH THE NUCLEUS.

SCHRODINGER THEORY: HE MADE A MATEMATICAL ECUATION TO FIND AN ELECTRON NEAR THE NUCLEUS.HE, WHIT WERNER HISEMBERG MADE A MODEL OF THE ATOM.

DANIEL RIVER LONDOÑO 7B 25/FEB/2010

<span style="color: #ff0000; display: block; font-family: Tahoma,Geneva,sans-serif; font-size: 140%; text-align: center;">athomic theories

<span style="color: #ff0000; font-family: Tahoma,Geneva,sans-serif; font-size: 140%;">1.modern atomics theories

john dalton: <span style="color: #000000; font-family: Arial,Helvetica,sans-serif; line-height: normal;">All matter is composed of atoms, All atoms of the same element are identical, Chemical reactions occur when atoms are rearranged, Compounds are formed from atoms of the constituent elements. []

<span style="color: #ff0000; font-family: Tahoma,Geneva,sans-serif; font-size: 140%;">thomson: <span style="-webkit-border-horizontal-spacing: 2px; -webkit-border-vertical-spacing: 2px; color: #326699; font-family: 'Times New Roman'; font-size: large; line-height: normal;"> <span style="font-family: Arial,Helvetica,sans-serif;">He assumed that the basic body of an atom is a spherical object containing N electrons confined in homogeneous jellylike but relatively massive positive charge distribution whose total charge cancels that of the N electrons <span style="font-family: Arial,Helvetica,sans-serif; font-size: 60%;">. []

<span style="color: #ff0000; font-family: Tahoma,Geneva,sans-serif; font-size: 140%;">rutherford: <span style="color: #000000; font-family: Arial,Helvetica,sans-serif; line-height: 18px;">positively charged core called a nucleus, in which nearly all the mass is concentrated, around which the light, negative constituents, called electrons, circulate at some distance, much like planets revolving around the Sun <span style="color: #333333; font-family: Arial,'Arial Unicode MS',Helvetica,sans-serif; font-size: 12px; line-height: 18px;">. []

<span style="color: #ff0000; font-family: Tahoma,Geneva,sans-serif; font-size: 140%;">bohr: depicts the atom as a small, positively charged nucleus surrounded by electrons that travel in circular orbits around the nucleus—similar in structure to the solar system, but with electrostatic forces providing attraction, rather than gravity.

ATOMS

In chemistry and physics, atom (of the Latin atomum, and this one of the Greek , without parts(reports)) [1] is the smallest unit of a chemical element that supports his(her,your) identity or his(her,your) properties and that is not possible to divide by means of chemical processes. The concept of atom like basic and indivisible block that composes the matter of th e universe was postulated by the school atomista in the Antigua Greece. Nevertheless, his(her,your) existence did not remain demonstrated up to the 19th century. With the development of the nuclear physics in the 20th century there was verified that the atom can subdivide in smaller particles TAKE WITH WIKIPEDIA/GOOGLE.COM by juan camilo diaz

Ancient Theories of Atom

The word //atom// was coined somewhere around 450 B.C. (it is an unfortunate side note about this period of history that it is usually quite difficult to give precise dates; one wishes that the ancient Greeks would have been a little bit better at keeping track of their activities) by a philosopher (which, at the time, was the same thing as a scientist) named Democritus.

What is Known about Democritus
Democritus was a student of Leucippus, who is said to also have subscribed to the atomic theory, though so very little is known about the actual works of both of these men that it becomes very difficult to tell where the theories of one ends and the other begins. Leucippus was said to have been influenced greatly by his contemporary, [|**Zeno of Elea**], which may explain some of his iconoclastic views on the substance of things. While Leucippus is credited by many to have been the true “creator” of atomic theory, he is more often than not overshadowed by Democritus, who did much more to systematize this view. Though there was still not much to it. Just as the sand on the seashore, so went the logic of Democritus, when viewed from afar looks to be a single body – a “beach” – so also may all matter be made up of tiny little granules of matter – the smallest of which he called atoms, which in Greek means, “uncuttable.” By virtue of the name itself, an atom in Democritus’ theory was the smallest thing in existence. It is difficult to say just how “scientific” atomic theory was in the case of Democritus – was it a real theory, developed using something similar to today’s scientific method, based on factual observation and deductive logic? Or was it a lucky shot in the dark? The jury is still out on this one, though one must give Democritus credit for his undeniably witty observation, “Nothing exists except atoms and empty space; everything else is opinion.” []1

<span style="color: #ff0000; font-family: Tahoma,Geneva,sans-serif; font-size: 160%;">thomson theory
 * <span style="font-family: Arial,Helvetica,sans-serif; font-size: 120%;"><span class="long_text"> The "Plum pudding model, also known as the raisin pudding, is a theory about the structure of an atom.En this model, the atom is composed of negatively charged electrons in a positive atom, like raisins in a pudding. Since the atom is no less a material system that contains a certain amount of external power, this causes a degree of attraction of the electrons in the atomic structure. From this point of view can be interpreted as Thomson's atomic model is a current model because of the elasticity of the electrons in the cosine of that structure.

<span style="font-family: Arial,Helvetica,sans-serif; font-size: 80%;">[] **

era || <span style="font-family: 'Arial Black',Gadget,sans-serif;">[|Democritus] || <span style="font-family: 'Arial Black',Gadget,sans-serif;">"by convention bitter, by convention sweet, but in reality atoms and void" || [|Hahn], Strassman || <span style="font-family: 'Arial Black',Gadget,sans-serif;">Conducted experiments verifying that heavy elements capture neutrons and form unstable products which undergo fission. This process ejects more neutrons continuing the fission chain reaction. ||
 * **<span style="font-family: 'Arial Black',Gadget,sans-serif;">[|Early theories]of the structure of matter were not based upon experiments. As scientists began to study the relationship between several physical phenomenon such as electricity, and magnetism they began to develop different models about atomic structure. ** ||
 * ||  ||   ||   || <span style="font-family: 'Arial Black',Gadget,sans-serif;">Year Scientist(s) Discovery ||
 * <span style="font-family: 'Arial Black',Gadget,sans-serif;">Greek
 * <span style="font-family: 'Arial Black',Gadget,sans-serif;">1704 || <span style="font-family: 'Arial Black',Gadget,sans-serif;">[|Isaac Newton] || <span style="font-family: 'Arial Black',Gadget,sans-serif;">Proposed a mechanical universe with small solid masses in motion. ||
 * <span style="font-family: 'Arial Black',Gadget,sans-serif;">1803 || <span style="font-family: 'Arial Black',Gadget,sans-serif;">[|John Dalton] || <span style="font-family: 'Arial Black',Gadget,sans-serif;">Proposed an "atomic theory" with spherical solid atoms based upon measurable properties of mass. ||
 * <span style="font-family: 'Arial Black',Gadget,sans-serif;">1832 || <span style="font-family: 'Arial Black',Gadget,sans-serif;">[|Michael Faraday] || <span style="font-family: 'Arial Black',Gadget,sans-serif;">Studied the effect of electricity on solutions, coined term "electrolysis" as a splitting of molecules with electricity, developed laws of electrolysis. Faraday himself was not a proponent of atomism. ||
 * <span style="font-family: 'Arial Black',Gadget,sans-serif;">1859 || <span style="font-family: 'Arial Black',Gadget,sans-serif;">J. Plucker || <span style="font-family: 'Arial Black',Gadget,sans-serif;">Built one of the first gas discharge tubes ("cathode ray tube"). ||
 * <span style="font-family: 'Arial Black',Gadget,sans-serif;">1869 || <span style="font-family: 'Arial Black',Gadget,sans-serif;">[|Dmitri Mendeleev] || <span style="font-family: 'Arial Black',Gadget,sans-serif;">Arranged elements into 7 groups with similar properties. He discovered that the properties of elements "were periodic functions of the their atomic weights". This became known as the Periodic Law. ||
 * <span style="font-family: 'Arial Black',Gadget,sans-serif;">1873 || <span style="font-family: 'Arial Black',Gadget,sans-serif;">[|James Clerk Maxwell] || <span style="font-family: 'Arial Black',Gadget,sans-serif;">Proposed electric and magnetic fields filled the void. ||
 * <span style="font-family: 'Arial Black',Gadget,sans-serif;">1879 || <span style="font-family: 'Arial Black',Gadget,sans-serif;">[|Sir William Crookes] || <span style="font-family: 'Arial Black',Gadget,sans-serif;">Discovered cathode rays had the following properties: travel in straight lines from the cathode; cause glass to fluoresce; impart a negative charge to objects they strike; are deflected by electric fields and magnets to suggest a negative charge; cause pinwheels in their path to spin indicating they have mass. ||
 * <span style="font-family: 'Arial Black',Gadget,sans-serif;">1886 || <span style="font-family: 'Arial Black',Gadget,sans-serif;">E. Goldstein || <span style="font-family: 'Arial Black',Gadget,sans-serif;">Used a CRT to study "canal rays" which had electrical and magnetic properties opposite of an electron. ||
 * <span style="font-family: 'Arial Black',Gadget,sans-serif;">1894 || <span style="font-family: 'Arial Black',Gadget,sans-serif;">[|G.J. Stoney] || <span style="font-family: 'Arial Black',Gadget,sans-serif;">Proposed that electricity was made of discrete negative particles he called [|electrons]". (Link to info on electrons) ||
 * <span style="font-family: 'Arial Black',Gadget,sans-serif;">1895 || <span style="font-family: 'Arial Black',Gadget,sans-serif;">[|Wilhelm Roentgen] || <span style="font-family: 'Arial Black',Gadget,sans-serif;">Using a CRT he observed that nearby chemicals glowed. Further experiments found very penetrating rays coming from the CRT that were not deflected by a magnetic field. He named them "X-rays". ||
 * <span style="font-family: 'Arial Black',Gadget,sans-serif;">1896 || <span style="font-family: 'Arial Black',Gadget,sans-serif;">[|Henri Becquerel] || <span style="font-family: 'Arial Black',Gadget,sans-serif;">While studying the effect of x-rays on photographic film, he discovered some chemicals spontaneously decompose and give off very pentrating rays. ||
 * <span style="font-family: 'Arial Black',Gadget,sans-serif;">1897 || <span style="font-family: 'Arial Black',Gadget,sans-serif;">[|J.J. Thomson] || <span style="font-family: 'Arial Black',Gadget,sans-serif;">Used a [|CRT]to experimentally determine the charge to mass ratio [|(e/m)]of an electron =1.759 x 10 8 coulombs/gram. ||
 * <span style="font-family: 'Arial Black',Gadget,sans-serif;">1897 || <span style="font-family: 'Arial Black',Gadget,sans-serif;">[|J.J. Thomson] || <span style="font-family: 'Arial Black',Gadget,sans-serif;">Studied "canal rays" and found they were associated with the proton H + . ||
 * <span style="font-family: 'Arial Black',Gadget,sans-serif;">1898 || <span style="font-family: 'Arial Black',Gadget,sans-serif;">[|Rutherford] || <span style="font-family: 'Arial Black',Gadget,sans-serif;">Studied radiations emitted from uranium and thorium and named them //alpha// and //beta.// ||
 * <span style="font-family: 'Arial Black',Gadget,sans-serif;">1898 || <span style="font-family: 'Arial Black',Gadget,sans-serif;">[|Marie Sklodowska Curie] || <span style="font-family: 'Arial Black',Gadget,sans-serif;">Studied uranium and thorium and called their spontaneous decay process "radioactivity". She and her husband Pierre also discovered the radioactive elements polonium and radium. ||
 * <span style="font-family: 'Arial Black',Gadget,sans-serif;">1900 || <span style="font-family: 'Arial Black',Gadget,sans-serif;">[|Soddy] || <span style="font-family: 'Arial Black',Gadget,sans-serif;">Observed spontaneous disintegration of radioactive elements into variants he called "isotopes" or totally new elements, discovered "half-life", made initial calculations on energy released during decay. ||
 * <span style="font-family: 'Arial Black',Gadget,sans-serif;">1900 || <span style="font-family: 'Arial Black',Gadget,sans-serif;">[|Max Planck] || <span style="font-family: 'Arial Black',Gadget,sans-serif;">used the idea of quanta (discrete units of energy) to explain hot glowing matter. ||
 * <span style="font-family: 'Arial Black',Gadget,sans-serif;">1903 || <span style="font-family: 'Arial Black',Gadget,sans-serif;">[|Nagaoka] || <span style="font-family: 'Arial Black',Gadget,sans-serif;">Postulated a "Saturnian" model of the atom with flat rings of electrons revolving around a positively charged particle. ||
 * <span style="font-family: 'Arial Black',Gadget,sans-serif;">1904 || <span style="font-family: 'Arial Black',Gadget,sans-serif;">Abegg || <span style="font-family: 'Arial Black',Gadget,sans-serif;">Discovered that inert gases had a stable electron configuration which lead to their chemical inactivity. ||
 * <span style="font-family: 'Arial Black',Gadget,sans-serif;">1905 || <span style="font-family: 'Arial Black',Gadget,sans-serif;">[|Albert Einstein] || <span style="font-family: 'Arial Black',Gadget,sans-serif;">Published the famous equation [|E=mc 2] ||
 * <span style="font-family: 'Arial Black',Gadget,sans-serif;">1906 || <span style="font-family: 'Arial Black',Gadget,sans-serif;">[|Hans Geiger] || <span style="font-family: 'Arial Black',Gadget,sans-serif;">Developed an electrical device to "click" when hit with alpha particles. ||
 * <span style="font-family: 'Arial Black',Gadget,sans-serif;">1909 || <span style="font-family: 'Arial Black',Gadget,sans-serif;">[|R.A. Millikan] || <span style="font-family: 'Arial Black',Gadget,sans-serif;">Oil drop experiment determined the charge (e=1.602 x 10 -19 coulomb) and the mass (m = 9.11 x 10 -28 gram) of an electron. ||
 * <span style="font-family: 'Arial Black',Gadget,sans-serif;">1911 || <span style="font-family: 'Arial Black',Gadget,sans-serif;">[|Ernest Rutherford] || <span style="font-family: 'Arial Black',Gadget,sans-serif;">Using alpha particles as atomic bullets, probed the atoms in a piece of thin (0.00006 cm) [|gold foil]. He established that the nucleus was: very dense,very small and positively charged. He also assumed that the electrons were located outside the nucleus. ||
 * <span style="font-family: 'Arial Black',Gadget,sans-serif;">1914 || <span style="font-family: 'Arial Black',Gadget,sans-serif;">[|H.G.J. Moseley] || <span style="font-family: 'Arial Black',Gadget,sans-serif;">Using x-ray tubes, determined the charges on the nuclei of most atoms. He wrote"The atomic number of an element is equal to the number of protons in the nucleus". This work was used to reorganize the periodic table based upon atomic number instead of atomic mass. ||
 * <span style="font-family: 'Arial Black',Gadget,sans-serif;">1919 || <span style="font-family: 'Arial Black',Gadget,sans-serif;">Aston || <span style="font-family: 'Arial Black',Gadget,sans-serif;">Discovered the existence of isotopes through the use of a mass spectrograph. ||
 * <span style="font-family: 'Arial Black',Gadget,sans-serif;">1922 || <span style="font-family: 'Arial Black',Gadget,sans-serif;">[|Niels Bohr] || <span style="font-family: 'Arial Black',Gadget,sans-serif;">Developed an explanation of atomic structure that underlies regularities of the periodic table of elements. His atomic model had atoms built up of sucessive orbital shells of electrons. ||
 * <span style="font-family: 'Arial Black',Gadget,sans-serif;">1923 || <span style="font-family: 'Arial Black',Gadget,sans-serif;">[|de Broglie] || <span style="font-family: 'Arial Black',Gadget,sans-serif;">Discovered that electrons had a dual nature-similar to both particles and waves. Particle/wave duality. Supported Einstein. ||
 * <span style="font-family: 'Arial Black',Gadget,sans-serif;">1927 || <span style="font-family: 'Arial Black',Gadget,sans-serif;">[|Heisenberg] || <span style="font-family: 'Arial Black',Gadget,sans-serif;">Described atoms by means of formula connected to the frequencies of spectral lines. Proposed Principle of Indeterminancy - you can not know both the position and velocity of a particle. ||
 * <span style="font-family: 'Arial Black',Gadget,sans-serif;">1929 || <span style="font-family: 'Arial Black',Gadget,sans-serif;">[|Cockcroft / Walton] || <span style="font-family: 'Arial Black',Gadget,sans-serif;">Built an early linear accelerator and bombarded lithium with protons to produce //alpha particles// ||
 * <span style="font-family: 'Arial Black',Gadget,sans-serif;">1930 || <span style="font-family: 'Arial Black',Gadget,sans-serif;">[|Schrodinger] || <span style="font-family: 'Arial Black',Gadget,sans-serif;">Viewed electrons as continuous clouds and introduced "wave mechanics" as a mathematical model of the atom. ||
 * <span style="font-family: 'Arial Black',Gadget,sans-serif;">1930 || <span style="font-family: 'Arial Black',Gadget,sans-serif;">[|Paul Dirac] || <span style="font-family: 'Arial Black',Gadget,sans-serif;">Proposed //anti-particles// . Anderson discovered the anti-electron (positron) in 1932 and Segre/Chamberlain detected the anti-proton in 1955.. ||
 * <span style="font-family: 'Arial Black',Gadget,sans-serif;">1932 || <span style="font-family: 'Arial Black',Gadget,sans-serif;">[|James Chadwick] || <span style="font-family: 'Arial Black',Gadget,sans-serif;">Using alpha particles discovered a neutral atomic particle with a mass close to a proton. Thus was discovered the neutron. ||
 * <span style="font-family: 'Arial Black',Gadget,sans-serif;">1938 || <span style="font-family: 'Arial Black',Gadget,sans-serif;">[|Lise Meitner,]
 * <span style="font-family: 'Arial Black',Gadget,sans-serif;">1941 - 51 || <span style="font-family: 'Arial Black',Gadget,sans-serif;">[|Glenn Seaborg] || <span style="font-family: 'Arial Black',Gadget,sans-serif;">Synthesized 6 transuranium elements and suggested a change in the layout of the periodic table. ||
 * <span style="font-family: 'Arial Black',Gadget,sans-serif;">1942 || <span style="font-family: 'Arial Black',Gadget,sans-serif;">[|Enrico Fermi] || <span style="font-family: 'Arial Black',Gadget,sans-serif;">Conducted the first controlled chain reaction releasing energy from the atoms nucleus. ||
 * <span style="font-family: 'Arial Black',Gadget,sans-serif;">1950's - || <span style="font-family: 'Arial Black',Gadget,sans-serif;">[|New findings/particles] || <span style="font-family: 'Arial Black',Gadget,sans-serif;">Follow this link to current theories about atomic stucture ||  ||

a.tomictimeline.net/index,php.

**Ernest rutherford theory:**

taken of:
 * Ernest Rutherford publishes his atomic theory describing the atom as having a central positive nucleus surrounded by negative orbiting electrons. This model suggested that most of the mass of the atom was contained in the small nucleus, and that the rest of the atom was mostly empty space. Rutherford came to this conclusion following the results of his famous gold foil experiment. This experiment involved the firing of radioactive particles through minutely thin metal foils (notably gold) and detecting them using screens coated with zinc sulfide (a scintillator). Rutherford found that although the vast majority of particles passed straight through the foil approximately 1 in 8000 were deflected leading him to his theory that most of the atom was made up of 'empty space'.

// __[]__ // [|//http://www.cfo.doe.gov/me70/manhattan/images/AtomLabeled.gif//] //​// **

In chemistry and physics **atomic theory** is a theory of the nature of matter, which states that matter is composed of discrete units called atoms, as opposed to the obsolete notion that matter could be divided into any arbitrarily small quantity. It began as a philosophical concept in ancient Greece and India and entered the scientific mainstream in the early 19th century when discoveries in the field of chemistry showed that matter did indeed behave as if it were made up of particles. The word "atom" (from the ancient Greek adjective //atomos//, 'undivisible') was applied to the basic particle that constituted a chemical element, because the chemists of the era believed that these were the fundamental particles of matter. However, around the turn of the 20th century, through various experiments with electromagnetism and radioactivity, physicists discovered that the so-called "indivisible atom" was actually a conglomerate of various subatomic particles (chiefly, electrons, protons and neutrons) which can exist separately from each other. In fact, in certain extreme environments such as neutron stars, extreme temperature and pressure prevents atoms from existing at all. Since atoms were found to be actually divisible, physicists later invented the term "elementary particles" to describe indivisible particles. The field of science which studies subatomic particles is particle physics, and it is in this field that physicists hope to discover the true fundamental nature of matter.

take []

=<span style="background-color: #ffffff; color: #ff0300; font-family: Tahoma,Geneva,sans-serif;">Kinetic-molecular Theory = = =

<span style="background-color: #ffffff; font-family: Arial,Helvetica,sans-serif;"> The temperature of an ideal monatomic gas is a measure related to the average kinetic energy of its atoms as they move. In this animation, the size of helium atoms relative to their spacing is shown to scale under 1950 atmospheres of pressure. These room-temperature atoms have a certain, average speed (slowed down here two trillion fold).

Kinetic theory (or the kinetic or kinetic-molecular theory of gases) is the theory that gases are made up of a large number of small particles (atoms or molecules), all of which are in constant, random motion. The rapidly moving particles constantly collide with each other and with the walls of the container. Kinetic theory explains macroscopic properties of gases, such as pressure, temperature, or volume, by considering their molecular composition and motion. Essentially, the theory posits that pressure is due not to static repulsion between molecules, as was Isaac Newton's conjecture, but due to collisions between molecules moving at different velocities.

While the particles making up a gas are too small to be visible, the jittering motion of pollen grains or dust particles which can be seen under a microscope, known as Brownian motion, results directly from collisions between the particle and air molecules. This experimental evidence for kinetic theory, pointed out by Albert Einstein in 1905, is generally seen as having confirmed the existence of atoms and molecules. []

<span style="display: block; font-family: Tahoma,Geneva,sans-serif; font-size: 130%; text-align: center;"> <span style="color: #ff0300; display: block; font-family: Tahoma,Geneva,sans-serif; font-size: 130%; text-align: center;"> atomic theories <span style="display: block; font-family: Arial,Helvetica,sans-serif; text-align: left;">The idea of an atom -- the smallest particle of matter -- has intrigued mankind since the beginning of civilization. Throughout the centuries the "view" of the atom has changed. New ideas, and new technologies have influenced the model of the atom. This view of the atom is still a //Theory// and therefore it is still subject to change. The modern model of the atom is called the [|Quantum Model] and you will study this model in future grades (Grade 11 and 12 Chemistry & Physics). The chart below summarizes the various atomic models that have been developed during the course of history.

[] How Ernest Rutherford pioneered the orbital theory of atoms

Atoms were first discovered in the early 1800's by John Dalton, who acknowledged the "Atomic Theory of Matter", and the "Law of Multiple Proportions", and created the "Table of Atomic Masses". In the early 1900's, J.J. Thomson discovered electrons, a negative charged particle, two thousand times lighter than a hydrogen atom, and made the "Plum Pudding" model which represents an atom, having the small round bits in the pudding represent the electrons and other positively charged particles, which are now known as protons. Atoms have the same number of protons as electrons to make atoms neutral. J.J. Thomson was Ernest Rutherford's professor at [|Trinity College], Cambridge. Rutherford found the plum pudding model was incorrect. According to Thomson's model, protons and electrons aren't in any particular order, or located in any particular position. Atoms are far more complex and have more detail then the plum pudding model. Rutherford discovered that the electrons orbit the atoms nucleus, like how planets in the [|solar system] orbit the sun. Protons are contained in the nucleus. Most of the atoms mass are contained in the small nucleus, and the rest of the atom is mostly empty space. Rutherford's Gold Foil experiment, using atoms and radioactive particles, proved his idea. He experiment by firing radioactive particles through minutely thin gold foils and detecting them using screens coated with zinc sulfide (a scintillator). Almost all of the particles passed straight through the foil, approximately 1 in 8000 were deflected which lead to the theory that most of the atom was made up of empty space. The radioactive particles went straight through the atoms in the foil because there was nothing stopping it, as for the particles that were deflected, happened to run into the nucleus of the atom.

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