Biography rutherford

Ernest Rutherford was the son of James Rutherford, a farmer, and his wife Martha Thompson, originally from Hornchurch, Essex, England. James had emigrated from Perth, Scotland, "to raise a little flax and a lot of children". Ernest was born at Spring Grove (now Brightwater), near Nelson, New Zealand. His first name was mistakenly spelled Earnest when his birth was registered.
He studied at Havelock School and then Nelson College and won a scholarship to study at Canterbury College, University of New Zealand where he was president of the debating society, among other things. After gaining his BA, MA and BSc, and doing two years of research at the forefront of electrical technology, in 1895 Rutherford travelled to England for postgraduate study at theCavendish Laboratory, University of Cambridge (1895–1898) and he briefly held the world record for the distance over which electromagnetic waves could be detected.In 1900 he married Mary Georgina Newton (1876–1945); they had one daughter, Eileen Mary (1901–1930), who married Ralph Fowler.

Later years

He was knighted in 1914. In 1916 he was awarded the Hector Memorial Medal. In 1919 he returned to the Cavendish as Director. Under him, Nobel Prizes were awarded to Chadwick for discovering the neutron (in 1932), Cockcroft and Walton for an experiment which was to be known as splitting the atom using a particle accelerator, and Appleton for demonstrating the existence of theionosphere. He was admitted to the Order of Merit in 1925 and in 1931 was created Baron Rutherford of Nelson, of Cambridge in the County of Cambridge, a title that became extinct upon his unexpected death in hospital following an operation for an umbilical hernia (1937). Since he was a peer, British protocol at that time required that he be operated on by a titled doctor, and the delay cost him his life. He is interred in Westminster Abbey, alongside J. J. Thomson, and near Sir Isaac Newton.

external image rutherford.jpg
taken from http://es.wikipedia.org/wiki/Ernest_Rutherford

biography broglie

es.wikipedia.org/wiki/Louis-Victor_de_Broglie
external image louis-de-broglie.jpg


De Broglie was born in Dieppe, Seine-Maritime, younger son of Victor, 5th duc de Broglie and a descendant of Madame de Staël. In 1960, upon the death without heir of his older brother, Maurice, 6th duc de Broglie, also a physicist, he became the 7th duc de Broglie. He never married. When he died in Louveciennes, he was succeeded as duke by a distant cousin, Victor-François, 8th duc de Broglie.
De Broglie had originally intended a career in humanities, and received his first degree in history. Afterwards, though, he turned his attention toward mathematics and physics. With the outbreak of the First World War in 1914, he offered his services to the army in the development of radio communications.
His 1924 doctoral thesis, Recherches sur la théorie des quanta (Research on Quantum Theory), introduced his theory of electron waves. This included the wave-particle duality theory of matter, based on the work of Albert Einstein and Max Planck on light. The thesis examiners, unsure of the material, passed his thesis to Einstein for evaluation who endorsed his wave-particle duality proposal wholeheartedly; de Broglie was awarded his doctorate. This research culminated in the de Broglie hypothesis stating that any moving particle or object had an associated wave. De Broglie thus created a new field in physics, the mécanique ondulatoire, or wave mechanics, uniting the physics of light and matter. For this he won the Nobel Prize in Physics in 1929. Among the applications of this work has been the development of electron microscopes to get much better image resolution than optical ones, because of the shorter wavelengths of electrons compared with photons.





what is atom theory?
Atomic model" redirects here. For the unrelated term in mathematical logic, see **Atomic model mathematical logig**
This article focuses on the historical models of the atom. For a history of the study of how atoms combine to form molecules, see History of molecular theory.
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.
external image atom-and-bohr.jpg

taken from:www.wikipedia.org
john dalton theory:

Democritus first suggested the existence of the atom but it took almost two millennia before the atom was placed on a solid foothold as a fundamental chemical object by John Dalton (1766-1844). Although two centuries old, Dalton's atomic theory remains valid in modern chemical thought.

external image s4_dalton.jpg


taken from:www.theryatomic.com.co

j.j thomson theory:
Until the final years of the nineteenth century, the accepted model of the atom resembled that of a billiard ball - a small, solid sphere. In 1897, J. J. Thomson dramatically changed the modern view of the atom with his discovery of the electron. Thomson's work suggested that the atom was not an "indivisible" particle as John Dalton had suggested but, a jigsaw puzzle made of smaller pieces.
Thomson's notion of the electron came from his work with a nineteenth century scientific curiosity: the cathode ray tube. For years scientists had known that if an electric current was passed through a vacuum tube, a stream of glowing material could be seen; however, no one could explain why. Thomson found that the mysterious glowing stream would bend toward a positively charged electric plate. Thomson theorized, and was later proven correct, that the stream was in fact made up of small particles, pieces of atoms that carried a negative charge. These particles were later named electrons.


external image j_thomson.jpg

taken from:www.theoryatomic.com.co



e.rutherford theory:

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.


taken from:http://www.rsc.org/chemsoc/timelinepages/1911.html



external image aLord_Ernest_Rutherford_-_1908-357x480.png




n.bohr theory:


In atomic physics the Bohr model, devised by Niels 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. This was an improvement on the earlier cubic model (1902), the plum-pudding model (1904), the Saturnian model (1904), and the Rutherford model (1911). Since the Bohr model is a quantum physics-based modification of the Rutherford model, many sources combine the two, referring to the Rutherford–Bohr model.
Introduced by Niels Bohr in 1913 the model's key success lay in explaining the Rydberg formula for the spectral emission lines of atomic hydrogen. While the Rydberg formula had been known experimentally, it did not gain a theoretical underpinning until the Bohr model was introduced. Not only did the Bohr model explain the reason for the structure of the Rydberg formula, it also provided a justification for its empirical results in terms of fundamental physical constants.


taken from:http://en.wikipedia.org/wiki/Bohr_model

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Further progress in the understanding of atoms did not occur until the science of chemistry began to develop. In 1661, matural philosopher Robert Boyle published The Sceptical Chymist in which he argued that matter was composed of various combinations of different "corpuscules" or atoms, rather than the classical elements of air, earth, fire and water. In 1789 the term element was defined by the French nobleman and scientific researcher Antoine Lavoisier to mean basic substances that could not be further broken down by the methods of chemistry.
In 1803, English instructor and natural philosopher John Dalton used the concept of atoms to explain why elements always react in a ratio of small whole numbers the law of multiple proportions and why certain gases dissolve better in water than others. He proposed that each element consists of atoms of a single, unique type, and that these atoms can join together to form chemical compounds. Dalton is considered the originator of modern atomic theory.
Additional validation of particle theory (and by extension atomic theory occurred in 1827 when botanist Robert Brown used a microscope to look at dust grains floating in water and discovered that they moved about erratically—a phenomenon that became known as "Brownian motion". J. Desaulx suggested in 1877 that the phenomenon was caused by the thermal motion of water molecules, and in 1905 Albert Enstein produced the first mathematical analysis of the motion. French physicist Jean Perrin used Einstein's work to experimentally determine the mass and dimensions of atoms, thereby conclusively verifying Dalton's atomic theory.
external image 500px-Periodic_table.svg.pngexternal image magnify-clip.pngA modern periodic table


the atomic theory

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'[1]) 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.













the atomic theory

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'[1]) 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.


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the atomic theory

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'[1]) 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.











In 1869, building upon earlier discoveries by such scientists as Lavoisier, Dmitri Mendeleev published the first functional periodic table. The table itself is a visual representation of the periodic law which states certain chemical properties of elements repeat
periodically when arranged by atomic number.http://en.wikipedia.org/wiki/Atom#Origin_of_scientific_the
atomics theories
"Atomic model" redirects here. For the unrelated term in mathematical logic, see **Atomic model (mathematical logic)**.
This article focuses on the historical models of the atom. For a history of the study of how atoms combine to form molecules, see **History of molecular theory**.
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'[[#cite_note-0|[1]]]) 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.
taken from: wikipedia free enciclopedi


external image 19921-medium.jpg

theories




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 . The chart below summarizes the various atomic models that have been developed during the course of history.


Atom_diagram.jpg





















John Dalton developed an atomic theory in which he proposed that each chemical element is composed of atoms of a single, unique type, and though they cannot be altered or destroyed by chemical means, they can combine to form more complex structures .This marked the first truly scientific theory of the atom, since Dalton reached his conclusions by experimentation and examination of the results in an empirical fashion. It is unclear to what extent his atomic theory might have been inspired by earlier ideas.


















In 1897 the physicist Joseph John (J. J.) Thomson (1856–1940) discovered the electron in a series of experiments designed to study the nature of electric discharge in a high-vacuum cathode-ray tube—an area being investigated by numerous scientists at the time. Thomson interpreted the deflection of the rays by electrically charged plates and magnets as evidence of "bodies much smaller than atoms" that he calculated as having a very large value for the charge to mass ratio. Later he estimated the value of the charge itself.






In 1904 he suggested a model of the atom as a sphere of positive matter in which electrons are positioned by electrostatic forces. His efforts to estimate the number of electrons in an atom
Rutherford's gold foil experiment, performed in conjunction with Geiger and Marsden, provided evidence for the nucleus due to the scattering of alpha particles. The repulsion of some alpha particles suggested that the nucleus is positively charged,
containing protons. Further work by Chadwick revealed the existence of neutrons within the nucleus of the atom. The atomic number describes the number of protons in the nucleus. For a neutral atom this is also the number of electrons outside the nucleus



this theories help to do the modern atomic theory




Atomic
theory is the idea that matter is made up of little units called atoms. When the ancient Greek philosopher Democritus came up with the idea in the 5th century BC, is was originally meant to refer to indivisible units. As of 1897, the British scientist J.J. Thomson discovered that atoms are in fact made up of smaller particles. Today atomic theoryrefers to matter being made up of units that are indivisible only some of the time. Exceptions include plasmas such as fire, other ionic arrangements such as those found in the body, radioactive materials, and many more.

taken from: http://www.youtube.com/watch?v=AVnoTq3JjbU&feature=related, http://www.wisegeek.com/what-is-atomic-theory.htm , http://en.wikipedia.org/wiki/Atomic_theory , http://www.visionlearning.com/library/module_viewer.php?mid=50 , http://library.thinkquest.org/27948/bohr.html , http://www.youtube.com/watch?v=RW_zfKOU9uM
DEMOCRITUS : of - Greek philosopher; pupil of Leucippus; developed atomic theory; elaborated idea that matter consisted of atoms having physical size and shape which constantly moved in a void and interacted in different ways; Greek word atoma means indivisible.

EMPEDOCLES: Some suggest (c.484-c.424) - Greek doctor, poet and philosopher. To account for real change, he assumed that there must be more than one kind of matter, and he postulated four roots as elements; earth, air, fire, and water. Love and hate were considered principles of attraction and repulsion that alternately dominated the universe in a recurring cycle. Empedocles presented a kind of biological theory of natural selection in an imaginative poem,
On Nature.

- Greek philosopher; pupil of Socrates; dealt with the nature of the universe; developed atomic theory of chemical change; ascribed geometric forms composed of bounding planes to the elements of earth, fire, air and water based upon their physical properties; held that elements could convert into one another through rearrangement of bounding planes; used deductive reasoning as a learning method.

ARISTOTLE: updated engraving; Greek philosopher, educator and scientist; undertook a large-scale classification of plants and animals; introduced a method of scientific thinking that still plays a role today.

ROBERT BOYLE: English physicist and chemist; experimented in pneumatics; through research, he rejected the accepted definition of matter; proposed Boyle's Law (1662).
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JOHN DALTON: English chemist and physicist; professor of mathematics and natural philosophy (1793); developed atomic theory; his theory (1805) accounts for the law of conservation of mass, law of definite proportions and law of multiple proportions; produced the first table of atomic weights; colorblind and mostly self-taught.


WILLIAM CROOKES: English chemist and physicist; His investigations of the photographic process in the 1850s motivated his work in the new science of spectroscopy. Using its techniques, Crooks discovered (1861) the element thallium, which won him election to the Royal Society. His efforts in determining the weight of thalium in an evacuated chamber led to his research in vacuum physics.
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MARIE CURIE: French physicist; researched radioactivity; she and husband, Pierre, discovered radium and polonium (1898); they shared the Nobel Prize for physics (1903) with Becquerel; Marie received the Nobel Prize for chemistry (1911).

JJ THOMPSON: Discovered the electron, the isotopes, and the invention of the mass spectrometer. Thompson thought and atom was a positively charged matter in which electrons were distributed like raisins in a cake. Thompson proved that cathode rays carried a negative charge in 1895. His discoveries were made made over a few years from 1894 through 1912.
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ERNEST RUTHERFORD: British physicist from New Zealand; discovered several radioactive isotopes with colleagues (1899-1905); classified forms of radiation as alpha, beta, and gamma; received Nobel Prize for chemistry (1908); worked on submarine detection during WWII; developed atomic theory (1911); researched transmutational effects of alpha particles on gases (ca. 1919) and other elements.

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Taken from: http://www.3rd1000.com/history.htm


atomic theories

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.
http://en.wikipedia.org/wiki/Atomic_theory

external image atomo.jpg



John Dalton: he said:

  1. That the atom was indivisible and it compose the elements.
  2. The atoms of a given element are different from those of any other element; the atoms of different elements can be distinguished from one another by their respective relative atomic weights.
  3. Atoms of one element can combine with atoms of other elements to form chemical compounds; a given compound always has the same relative numbers of types of atoms.
  4. Atoms cannot be created, divided into smaller particles, nor destroyed in the chemical process; a chemical reaction simply changes the way atoms are grouped together.

external image thomps~1.gif


JJ Thomson:
  1. Discovered the electron.
  2. Atom is composed by electrons.
  3. Atom can be divided in other particles.
  4. The atom is neutral.
external image thomson.jpg






http://en.wikipedia.org/wiki/John_Dalton#Atomic_theory
atomic models

Since antiquity, humans have questioned what he was made the subject.
Some 400 years before Christ, the Greek philosopher Democritus believed that matter was made up of tiny particles that could not be divided into smaller ones. Therefore, these particles called atoms, which in Greek means "indivisible". Atoms Democritus attributed to the qualities of being eternal, immutable and indivisible. Empedocles said that matter was composed of earth, water, fire and air. Aristotle opposed the theory of Democritus and support part of Empedocles but said what mattered was the beginning of movement of atoms. Boyle said the atom had specific characteristics and formed elements are assembled to form compounds.


Age
Scientific
Experimental Discovers
Atomic Model
1808
dalton_m.jpg
John Dalton

During the eighteenth century and early nineteenth century scientists had investigated various aspects of chemical reactions, obtaining the so-called classical laws of chemistry.

reaccion.gif
The image of the atom described by Dalton in his atomic theory to explain these laws is that of tiny spherical particles, indivisible and unchangeable,
mod_dalt.gif
Dalton atomic model






1897
thomson_m.jpg
J.J. Thomson
This finding inferred that the atom had to be a sphere of positively charged matter, within which electrons were embedded.
He showed that within atoms are tiny particles with negative electric charge, which is called electron
tubo_cat.gif

Thomson atomic model

mod_thom.gif











1911

rutherf_m.jpg E.Rutherford
He deduced that the atom should be formed by a crust with electrons orbiting a positively charged nucleus.
He proved that atoms were not solid, as was thought, but are mostly empty and at its center is a tiny core
m_ruther.gif
Rutherford atomic model

atomo_r.gif





1913
Niels Bohr
bohr_m.jpg
Discrete atomic spectra caused by the radiation emitted by excited atoms of the elements in gaseous.
espectro_m.gif
Proposed a new atomic model, in which electrons orbit the nucleus at levels well defined
Bohr atomic model

atomo_b.gif













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taken from:http://concurso.cnice.mec.es/cnice2005/93_iniciacion_interactiva_materia/curso/materiales/atomo/modelos.htm




Electrons Can Behave as Waves: The Quantum Model of the Atom

Although the Bohr model adequately explained how atomic spectra worked, there were several problems that bothered physicists and chemists:
Why should electrons be confined to only specified energy levels?
Why don't electrons give off light all of the time?
As electrons change direction in their circular orbits (i.e., accelerate), they should give off light.
The Bohr model could explain the spectra of atoms with one electron in the outer shell very well, but was not very good for those with more than one electron in the outer shell.
Why could only two electrons fit in the first shell and why eight electrons in each shell after that? What was so special about two and eight?

Obviously, the Bohr model was missing something!
In 1924, a French physicist named Louis de Broglie suggested that, like light, electrons could act as both particles and waves (see De Broglie Phase Wave Animation for details). De Broglie's hypothesis was soon confirmed in experiments that showed electron beams could be diffracted or bent as they passed through a slit much like light could. So, the waves produced by an electron confined in its orbit about the nucleus sets up a standing wave of specific wavelength, energy and frequency (i.e., Bohr's energy levels) much like a guitar string sets up a standing wave when plucked.
Another question quickly followed de Broglie's idea. If an electron traveled as a wave, could you locate the precise position of the electron within the wave? A German physicist, Werner Heisenberg, answered no in what he called the uncertainty principle:
To view an electron in its orbit, you must shine a wavelength of light on it that is smaller than the electron's wavelength.
This small wavelength of light has a high energy.
The electron will absorb that energy.
The absorbed energy will change the electron's position.
We can never know both the momentum and position of an electron in an atom. Therefore, Heisenberg said that we shouldn't view electrons as moving in well-defined orbits about the nucleus!
With de Broglie's hypothesis and Heisenberg's uncertainty principle in mind, an Austrian physicist namedErwin Schrodinger derived a set of equations or wave functions in 1926 for electrons. According to Schrodinger, electrons confined in their orbits would set up standing waves and you could describe only the probability of where an electron could be. The distributions of these probabilities formed regions of space about the nucleus were called orbitals. Orbitals could be described as electron density clouds(see Atomic & Molecular Orbitals for a look at various orbitals). The densest area of the cloud is where you have the greatest probability of finding the electron and the least dense area is where you have the probability of finding the electron.

taken of http://www.howstuffworks.com/atom8.htm

http://www.youtube.com/watch?v=UXvAla2y9wc&feature=player_embedded


werner heisenberg



German theoretical physicist Werner Karl Heisenberg, b. Dec. 5, 1901, d. Feb. 1, 1976, was one of the leading scientists of the 20th century. He did important work in nuclear and particle physics, but his most significant contribution was to the development of quantum mechanics. He is best known for his uncertainty principle, which restricts the accuracy with which some properties of atoms and particles--such as position and linear momentum--can be determined simultaneously. Heisenberg studied physics at the University of Munich, where he worked under Arnold Sommerfeld. A lecture series by Niels Bohr convinced him to work on quantum theory. He went to Bohr's Copenhagen institute, where he collaborated with Dutch physicist Hendryk Kramers, and then to the University of Gottingen. There, in 1925, Heisenberg invented matrix mechanics, the first version of quantum mechanics. In subsequent work with German physicists Max Born and Pascual Jordan, he extended this into a complete mathematical theory of the behavior of atoms and their constituents. The physical principles underlying the mathematics of quantum mechanics remained mysterious until 1927, when Heisenberg--following conversations with Bohr and Albert Einstein--discovered the uncertainty principle. An important book Heisenberg published in 1928, The Physical Principles of Quantum Theory, described his ideas. The previous year he had become a professor at the University of Leipzig, and in 1932 he was awarded the Nobel prize in physics. He remained in Germany during the Nazi period and became director of the Kaiser Wilhelm Institute, also heading the unsuccessful German nuclear weapons project. In 1958, Heisenberg became director of the Max Planck Institute for Physics and Astrophysics. He spent his later years working toward a general theory of subatomic particles. Heisenberg's work has had important influences in philosophy as well as physics. Some of his own works, such as Physics and Philosophy (1962) and Physics and Beyond (1971), deal with philosophical issues.

external image portrait-heisenberg-600w.jpg

taken from :http://library.thinkquest.org/15567/bio/heisenberg.html



ATOMIC THEORIES

Rutherford's gold foil experiment, performed in conjunction with Geiger and Marsden, provided evidence for the nucleus due to the scattering of alpha particles. The repulsion of some alpha particles suggested that the nucleus is positively charged, containing protons. Further work by Chadwick revealed the existence of neutrons within the nucleus of the atom. The atomic number describes the number of protons in the nucleus. For a neutral atom this is also the number of electrons outside the nucleus. Subtracting the atomic number from the atomic mass number gives the number of neutrons in the nucleus. Isotopes are atoms of the same element (i.e., they have the same number of protons, or the same atomic number) which have a different number of neutrons in the nucleus. Isotopes of an element have similar chemical properties. Radioactive isotopes are called radioisotopes. Most of the elements in the periodic table have several isotopes, found in varying proportions for any given element. The average atomic mass of an element takes into account the relative proportions of its isotopes found in nature. A nuclear binding force holds the nucleus of the atom together. The nuclear mass defect, a slightly lower mass of the nucleus compared to the sum of the masses of its constituent matter, is due to the nuclear binding energy holding the nucleus together. The mass defect can be used to calculate the nuclear binding energy, with E = mc2. The average binding energy per nucleon is a measure of nuclear stability. The higher the average binding energy, the more stable the nucleus.


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The Bohr's model of the atom described the electrons as orbiting in discrete, precisely defined circular orbits. Electrons can only occupy certain allowed orbitals. For an electron to occupy an allowed orbit, a certain amount of energy must be available. Each orbit is assigned a quantum number, with the lowest quantum numbers being assigned to those orbitals closest to the nucleus. Only a specified maximum number of electrons can occupy an orbital. Under normal circumstances, electrons occupy the lowest energy level orbitals closest to the nucleus. By absorbing additional energy, electrons can be promoted to higher orbitals, and release that energy when they return back to lower energy levels. The Bohr's model of the atom helped to offer one possible explanation for the emission spectrum formed by hydrogen and other gases. Photons are used to describe the wave-particle duality of light. The energy of a photon depends upon its frequency. This helps to explain the photoelectric effect; only photons having a sufficiently high energy are capable of dislodging an electron from the illuminated surface.
E = hv where E is the photon energy in J, v is the photon frequency in Hz, and h is Planck's constant,6.626 × 10-34 J / Hz. Quantum theory offers a mathematical model to help explain the nature of the atom. Quantum theory describes a region surrounding the nucleus which has the highest probability of locating an electron. These orbital "clouds" have some unusual and interesting shapes

Atom_diagram.jpg
//http://library.thinkquest.org/27948/bohr.html//


rare and theoretical forms
While isotopes with atomic numbers higher than lead are known to be radioactive, an "island of stability" has been proposed for some elements with atomic numbers above 103. These superheavy elements may have a nucleus that is relatively stable against radioactive decay. The most likely candidate for a stable superheavy atom, unbihexium, has 126 protons and 184 neutrons.
Each particle of matter has a corresponding antimatter particle with the opposite electrical charge. Thus, the positron is a positively charged antielectron and the antiproton is a negatively charged equivalent of a proton. When a matter and corresponding antimatter particle meet, they annihilate each other. Because of this, along with an imbalance between the number of matter and antimatter particles, the latter are rare in the universe. (The first causes of this imbalance is not yet fully understood, although the baryogenesis theories may offer an explanation.) As a result, no antimatter atoms have been discovered in nature. However, in 1996, antihydrogen, the antimatter counterpart of hydrogen, was synthesized at the CERN laboratory in Geneva.
Other exotic atoms have been created by replacing one of the protons, neutrons or electrons with other particles that have the same charge. For example, an electron can be replaced by a more massive muon, forming a muonic atom. These types of atoms can be used to test the fundamental predictions of physics.

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taken from:http://en.wikipedia.org/wiki/Atom#Rare_and_theoretical_forms







Philosophical atomism

Main article: Atomism
The concept that matter is composed of discrete units and cannot be divided into any arbitrarily small quantities has been around for thousands of years, but these ideas were founded in abstract, philosophical reasoning rather than scientific experimentation. The nature of atoms in philosophy varied considerably over time and between cultures and schools and often had spiritual elements. Nevertheless, the basic idea of the atom was adopted by scientists thousands of years later because it could elegantly explain new discoveries in the field of chemistry.

Indian

The earliest theory of atomism, in ancient India, can be found in Jainism. Some of the earliest known theories were also developed in the 2nd century BCE by Kanada, a Hindu philosopher. In Hindu philosophy, the Nyaya and Vaisheshika schools developed elaborate theories on how atoms combined into more complex objects (first in pairs, then trios of pairs), but believed the interactions were ultimately driven by the will of God (specifically, the Hindu Ishvara), and that the atoms themselves were otherwise inactive, without physical properties of their own. By contrast, Jain philosophy (6th Century BCE) linked the behavior of matter to the nature of the atoms themselves. Each atom, according to Jaina philosophy, has one kind of taste, one smell, one color, and two kinds of touch—each touch corresponding to negative and positive charge. The Jain school further postulated that atoms can exist in one of two states: subtle, in which case they can fit in infinitesimally small spaces, and gross, in which case they have extension and occupy a finite space. Although atoms are made of the same basic substance, they can combine based on their eternal properties to produce any of six “aggregates,” which seem to correspond with the Greek concept of “elements”: earth, water, shadow, sense objects, karmic matter, and unfit mat Greek
must be an indivisible unity, for if it were manifold, then there would have to be a void that could divide it (and he did not believe the void exists). Finally, he stated that the all encompassing Unity is unchanging, for the Unity already encompasses all that is and can b

Democritus accepted most of Parmenides' arguments, except for the idea that change is an illusion. He believed change was real, and if it was not then at least the illusion had to be explained. He thus supported the concept of void, and stated that the universe is made up of many Parmenidean entities that move around in the void.[[#cite_note-From_AtomosToAtom-6|[7]]] These entities, which are, are indeed unchangeable, but their arrangement in space is constantly changing. Democritus' atoms were made of the same material but had a limitless variety of shapes and sizes; this, coupled with their arrangement in space. explained all the different substances and objects in the universe.

[[[w/index.php?title=Atomic_theory&action=edit&section=4|edit]]] Islamic

See also: Corpuscularianism
The most successful form of Islamic atomism was in the Asharite school of Islamic theology, most notably in the work of the theologian Al-Ghazali (1058–1111). In Asharite atomism, atoms are the only perpetual, material things in existence, and all else in the world is "accidental" meaning something that lasts for only an instant. Nothing accidental can be the cause of anything else, except perception, as it exists for a moment. Contingent events are not subject to natural physical causes, but are the direct result of God's constant intervention, without which nothing could happen. Thus nature is completely dependent on God, which meshes with other Asharite Islamic ideas on causation, or the lack thereof (Gardet 2001). Al-Ghazali also used the theory to support his theory of occasionalism. In a sense, the Asharite theory of atomism has far more in common with Indian atomism than it does with Greek atomism.[[#cite_note-9|[10]]]
Corpuscularianism is the postulate that all physical bodies possess an inner and outer layer of minute particles or corpuscles. It has its origins in the speculations of the eighth-century Islamic alchemist
Geber,[[#cite_note-11|[12]]] but was expounded in a predominant manner by the 13th-century , Jabir ibn Hayyan (721-815), known in Europe as Geber,[[#cite_note-11|[12]]] but was expounded in a predominant manner by the 13th-century Pseudo-Geber.[[#cite_note-12|[13]]] Corpuscularianism is similar to the theory atomism, except that where atoms were supposed to be indivisible, corpuscles could in principle be divided. In this manner, for example, it was theorized that mercury could penetrate into metals and modify their inner structure, a step on the way towards transmutative production of gold. Corpuscularianism was associated by its leading proponents with the idea that some of the properties that objects appear to have are artifacts of the perceiving mind: 'secondary' qualities as distinguished from 'primary' qualities.[[#cite_note-13|[14]]] Corpuscularianism stayed a dominant theory over the next several hundred years and was blended with alchemy by those as Robert Boyle and Isaac Newton in the 17th century.[[#cite_note-Levere-10|[11]]][[#cite_note-14|[15]]] It was used by Newton, for instance, in his development of the corpuscular theory of light

PHILOSOFICAL ATOMISM
Main article: Atomism
The concept that matter is composed of discrete units and cannot be divided into any arbitrarily small quantities has been around for thousands of years, but these ideas were founded in abstract, philosophical reasoning rather than scientific experimentation. The nature of atoms in philosophy varied considerably over time and between cultures and schools and often had spiritual elements. Nevertheless, the basic idea of the atom was adopted by scientists thousands of years later because it could elegantly explain new discoveries in the field of chemistry.

Indian

The earliest theory of atomism, in ancient India, can be found in Jainism. Some of the earliest known theories were also developed in the 2nd century BCE by Kanada, a Hindu philosopher. In Hindu philosophy, the Nyaya and Vaisheshika schools developed elaborate theories on how atoms combined into more complex objects (first in pairs, then trios of pairs), but believed the interactions were ultimately driven by the will of God (specifically, the Hindu Ishvara), and that the atoms themselves were otherwise inactive, without physical properties of their own.[5] By contrast, Jain philosophy (6th Century BCE) linked the behavior of matter to the nature of the atoms themselves. Each atom, according to Jaina philosophy, has one kind of taste, one smell, one color, and two kinds of touch—each touch corresponding to negative and positive charge. The Jain school further postulated that atoms can exist in one of two states: subtle, in which case they can fit in infinitesimally small spaces, and gross, in which case they have extension and occupy a finite space. Although atoms are made of the same basic substance, they can combine based on their eternal properties to produce any of six “aggregates,” which seem to correspond with the Greek concept of “elements”: earth, water, shadow, sense objects, karmic matter, and unfit matter.

Greek

In the 5th century BC, Leucippus and his pupil Democritus proposed that all matter was composed of small indivisible particles called atoms, in order to reconcile two conflicting schools of thought on the nature of reality. On one side was Heraclitus, who believed that the nature of all existence is change. On the other side was Parmenides, who believed instead that all change is illusion.
Parmenides denied the existence of motion, change and void. He believed all existence to be a single, all-encompassing and unchanging mass (a concept known as monism), and that change and motion were mere illusions. This conclusion, as well as the reasoning that lead to it, may indeed seem baffling to the modern empirical mind, but Parmenides explicitly rejected sensory experience as the path to an understanding of the universe, and instead used purely abstract reasoning. Firstly, he believed there is no such thing as void, equating it with non-being (i.e. "if the void is, then it is not nothing; therefore it is not the void"). This in turn meant that motion is impossible, because there is no void to move into. He also wrote all that is must be an indivisible unity, for if it were manifold, then there would have to be a void that could divide it (and he did not believe the void exists). Finally, he stated that the all encompassing Unity is unchanging, for the Unity already encompasses all that is and can be.
Democritus accepted most of Parmenides' arguments, except for the idea that change is an illusion. He believed change was real, and if it was not then at least the illusion had to be explained. He thus supported the concept of void, and stated that the universe is made up of many Parmenidean entities that move around in the void. These entities, which are, are indeed unchangeable, but their arrangement in space is constantly changing. Democritus' atoms were made of the same material but had a limitless variety of shapes and sizes; this, coupled with their arrangement in space. explained all the different substances and objects in the universe.

Islamic

See also: Corpuscularianism
The most successful form of Islamic atomism was in the Asharite school of Islamic theology, most notably in the work of the theologian Al-Ghazali (1058–1111). In Asharite atomism, atoms are the only perpetual, material things in existence, and all else in the world is "accidental" meaning something that lasts for only an instant. Nothing accidental can be the cause of anything else, except perception, as it exists for a moment. Contingent events are not subject to natural physical causes, but are the direct result of God's constant intervention, without which nothing could happen. Thus nature is completely dependent on God, which meshes with other Asharite Islamic ideas on causation, or the lack thereof (Gardet 2001). Al-Ghazali also used the theory to support his theory of occasionalism. In a sense, the Asharite theory of atomism has far more in common with Indian atomism than it does with Greek atomism. Corpuscularianism is the postulate that all physical bodies possess an inner and outer layer of minute
particles or corpuscles. It has its origins in the speculations of the eighth-century Islamic alchemist, Jabir ibn Hayyan (721-815), known in Europe as Geber, but was expounded in a predominant manner by the 13th-century Pseudo-Geber. Corpuscularianism is similar to the theory atomism, except that where atoms were supposed to be indivisible, corpuscles could in principle be divided. In this manner, for example, it was theorized that mercury could penetrate into metals and modify their inner structure, a step on the way towards transmutative production of gold. Corpuscularianism was associated by its leading proponents with the idea that some of the properties that objects appear to have are artifacts of the perceiving mind: 'secondary' qualities as distinguished from 'primary' qualities.[14] Corpuscularianism stayed a dominant theory over the next several hundred years and was blended with alchemy by those as Robert Boyle and Isaac Newton in the 17th century.It was used by Newton, for instance, in his development of the corpuscular theory of light.
TAKEN FROM: http://en.wikipedia.org/wiki/Atomic_theory#Indian

"Atomic model" redirects here. For the unrelated term in mathematical logic, see Atomic model (mathematical logic).This article focuses on the historical models of the atom. For a history of the study of how atoms combine to form molecules, see History of molecular theory.
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'[1]) 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.

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Earliest empirical evidence


​Near the end of the 18th century, two laws about chemical reactions emerged without referring to the notion of an atomic theory. The first was the law of conservation of mass, formulated by Antoine Lavoisie in 1789, which states that the total mass in a chemical reaction remains constant (that is, the reactants have the same mass as the products). The second was the law of definite proportions. First proven by the French chemist Joseph Louis Proust in 1799, this law states that if a compound is broken down into its constituent elements, then the masses of the constituents will always have the same proportions, regardless of the quantity or source of the original substance.
external image Daltons_symbols.gifexternal image magnify-clip.pngVarious atoms and molecules as depicted in John Dalton's A New System of Chemical Philosophy (1808).
Based on this previous work and his own experiments, John Dalton developed an atomic theory in which he proposed that each chemical element is composed of atoms of a single, unique type, and though they cannot be altered or destroyed by chemical means, they can combine to form more complex structures (chemical compounds). This marked the first truly scientific theory of the atom, since Dalton reached his conclusions by experimentation and examination of the results in an empirical fashion. It is unclear to what extent his atomic theory might have been inspired by earlier ideas.
Dalton studied and expanded upon Proust's work to develop the law of multiple proportions: if two elements form more than one compound between them, then the ratios of the masses of the second element which combine with a fixed mass of the first element will be ratios of small integers. For instance, Proust had studied tin oxides and found that their masses were either 88.1% tin and 11.9% oxygen or 78.7% tin and 21.3% oxygen (these were tin(II) oxide and tin dioxide respectively). Dalton noted from these percentages that 100g of tin will combine either with 13.5g or 27g of oxygen - a ratio of 1:2. From this he concluded that the first was made up of one tin atom and one oxygen atom, and the latter one tin atom and two oxygen atoms.
Dalton also believed atomic theory could explain why water absorbed different gases in different proportions: for example, he found that water absorbed carbon dioxide far better than it absorbed nitrogen. Dalton hypothesized this was due to the differences in mass and complexity of the gases' respective particles. Indeed, carbon dioxide molecules (CO2) are heavier and larger than nitrogen molecules (N2).
In 1803 Dalton orally presented his first list of relative atomic weights for a number of substances. This paper was published in 1805, but he did not discuss there exactly how he obtained these figures. The method was first revealed in 1807 by his acquaintance Thomas Thomson, in the third edition of Thomson's textbook, A System of Chemistry. Finally, Dalton published a full account in his own textbook, A New System of Chemical Philosophy, 1808 and 1810.


CURIOUS FACTS ABOUT ATOMS
0) You never actually touch anything. Like when you are typing. The electrons in your finger tips repel the electrons in the keyboard keys. The part of the atom that contains mass, the nucleus, never touches another nucleus. Except in nuclear fusion and alpha particles. But everywhere else in the universe, the electromagnetic force between atoms keeps the nucleus's from ever touching.
1) the surface of your body is made up of electrons (usually) which repel other electrons, and your muscles are not strong enough to overcome this repulsion (neither are the atoms). This is why we can’t touch anything and this is why your hand never passes through your door handle like a ghost.

2) atoms are not the smallest particles in the universe. Atoms are made up of subatomic particles (protons, electrons, neutrons...). They are not the smallest particles in the universe either as they are made up of sub-subatomic particles such as quarks. I don't know of anything below quarks.

3) if you take an electron from an atom or lend it an extra electron, it becomes an ion (which is a fancy name for a charged atom). Some ions are made of several atoms bonded to each other. Ions are not molecules in their own right. Add two ions together and you get a compound (Such as Na+ and Cl- to make NaCl - Sodium(/Natrium) Chloride - table salt. There are many salts and they are largely inedible.

4) f you give or take a proton from an atom it becomes a completely different substance. in fact this is how nuclear bombs and nuclear power plants work.

5) atoms do different things depending on how you look at them and measure them. Have you heard of the "double slit experiement"? If you ever study optics in school or anything like that, ask your science teacher if they can show you. Light produces interference patterns because it is made of waves. However light can be made up of particles instead of waves. Similarly, electrons, protons, even whole atoms and molecules can be made of waves and NOT particles, if you measure the right properties. This is not a quirk of human perception, it's the duality of all matter.

6) Electrons are not "balls" and are not "lumpy things". In science class you may be lead to believe that electrons (the atom's usual negative constituents) are like little balls flying around the atoms. This is generally untrue. An electron exists in many points around the atom simultaneously, and is more like a standing wave of probability around the atom than it is like an actual discrete particle. Even the Lewis diagram, an invaluable tool for learning about chemistry, is kind of misleading when it comes to the nature of the actual atom and electon.

7) for each subatomic particle there is an equivalent "antiparticle". That's right, there is such a thing as antimatter in the real world. If matter and antimatter collide, both are annihilated.

8) Matter (atoms) can not be created or destroyed. The can be transformed and moved a thousand different ways, but never really destroyed. Ultimately, if the universe is only "so big", then based on what information we have now it will always weigh approximately the same. (This is due to the first law of thermodynamics, which CAN possibly be violated as with say for example Hawking Radiation)

9) You can sometimes know things about an atom that you've never measured, by knowing things about an atom that you are measuring. Quantum entanglement allows a particle to be opposite to its partner, no matter how far they drift apart.

10) It's possible that atoms do not strictly exist when you're not looking at them (Can't find a source, memory fails. Look at Schroedinger's Cat and Wavefunction Collapse for a hint on how this could happen)

11) the wires in your computer conduct electricity in part because they are lattices of atoms, and each atom can pass a electron on to the next atom down the wire.

12) The first man to split the atom was a scientist from New Zealand called Ernest Rutherford. One of the heavier atoms is named in his honour. Rutherford believed that we would never be able to do some of the things that we are able to do today, and yet we do them anyway.

13) You can change the properties of atoms today, after you lose them tomorrow. Retroactively. How atoms behave now depends as much on what you do tomorrow as on what you do now.

14) In certain conditions, atoms can flow up and out of their containers despite density and gravity.

15) Atoms are always warm. Atoms can't be without heat, and their temperature can't be zero degrees kelvin. So there is a limit to how cold you can go. Interestingly, if you have a negative temperature in Kelvins, then heat will flow OUT of you, making you for practical purposes extremely hot. Negative Kelvin temperatures show a greater than infinite temperature.


TAKEN FROM: http://au.answers.yahoo.com/question/index?qid=20090310024355AAB9bYH