Fall.2010.MMA.Maher.atomictimeline

 Ben Maher Mr. Reich  __**ANCIENT TIMES (450 AD and years prior) ** __   **__DEMOCRITUS __** Democritus was a Greek philosopher who lived between 470-380 B.C. Democritus of Abdera, Greece, proposed that matter was made up from atoms. There was no real evidence for this idea, but is v fdvtergevgrebgredbgfdgdfgdbvgebgrebgegtedb gdfbgrtdbgtrdbgdbgfd bgdgdbgte, which were microscopic and indestructible. The atoms were always moving and clustering in various, temporary combinations. Therefore, things seemed to change, but 'not being' never changed into 'being'. The consequence of this idea is that we are allowed to use our senses, although Democritus warns us to be careful. Democritus had a theory that stated that there are many different types of atoms that vary from different shapes and temperatures. Democritus did not have much evidence to back up his theory. So he did not recieve alot of credit untio thousands of years later when there was more progress on the atom and there was evidence to back it up.

 his atomic model

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** __LEUCIPPUS__ ** He was most likely born in Miletus but we dont know when he was born. It was sometime around the trojan war. Leucippus was the originator of the theory that the universe consists of two different elements, which he called ‘the full’ or ‘solid,’ and ‘the empty’ or ‘void’ he also beleived that the two things went on forever or in other words infinite. little is know about leucippus and some even queation if he even existed, his work was fallowed up by democritus and thats why when you hear about Leucippus he is also reffered to the co finder with democritus.



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**__ARISTOTLE__**

Aristotle was a Greek philosopher, a student of Plato and teacher of Alexander the Great. He was born in 384 BC in Thrace and died in 322 BC. He had science involed in his life from day one. Aristototle moved to Athens later in his life to work with Palto and thats really where he started to devlop his ideas of science in general. He also beleived a great deal in physicis, he stated that matter is made up of four elements fire, water, air, and earth. Aristotle was cleary the first to collect scientific information. He created a school that had the first science department that was excellent in biology.

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**__1700-1800__**

**__ANTOINE LAVOISIER__**

Antoine Lavoisier was in paris on August 26 1743 and died on May 8 1794. He is known as the father of modern chemistry and came out with the first chemistry text book. He conducted the first real quantitative tests on matter, which his results supported the conservation of matter. He discovered that water and air are not elements but compounds and mixtures. He also disproved the theory of phlogiston in objects that are combustible.



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**__CHARLES-AUGUSTIN de COULOMB__**

Charles-Augustin de Coulomb was born in France on September 14 1736 and died on August 23 1806. He was a French Chemists in Paris. He is best known for developing Coulomb's Law, the definition of the electrostatic force of attraction and repulsion. The SI unit of charge, the coulomb, was named after him. Coulomb's law is a law of physics describing the electrostatic interaction between electrically charged particles. He was essential to the development of the theory of electromagnetism.



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__**JOSEPH BLACK**__

Joseph Black was born in Scottland on April 16 1728 and died on December 6 1799. He was a Scottish physician, known for his discoveries of latent heat, specific head and carbon dioxide. James Watt, who was appointed as philosophical instrument maker at the same university (1756), became involved in Black's works and conducted experiments on steam with Black. He found that limestone could be heated or treated with acids to yield a gas he called "fixed air." He observed that the fixed air was denser than air and supported neither flame nor animal life. Black also found that when bubbled through an aqueous solution of lime, it would precipitate calcium carbonate.



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__**1800 - 1875**__

**__JOHN DALTON__** John Dalton was born in Cumberland, England on September 6 1766 and died on July 27 1844. He received a grammar school education, was taught math by a relative, and gained much of his scientific knowledge from the instruction of a blind philosopher named John Gough. His most important contribution to wht Chemistry world is the Atomic Theory which was developed betwwen 1802-1804. He determined 4 priciples of atoms: 1) All matter is made of atoms. Atoms are indivisible and indestructible. 2) All atoms of a given element are identical in mass and properties 3) Compounds are formed by a combination of two or more different kinds of atoms. 4) A chemical reaction is a rearrangement of atoms. Modern atomic theory is, of course, a little more involved than Dalton's theory but the essence of Dalton's theory remains valid. Many heretofore unexplained chemical phenomena were quickly explained by Dalton with his theory. Dalton's theory quickly became the theoretical foundation in chemistry.



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__**ANTOINE HENRI BECQUEREL**__

Antoine Henri Becquerel was bron on December 15, 1852 in Paris and died on August 25, 1908. He was a French Physicist and discovered of radioactivity along with Marie Curie and Pierre Curie for which they won the Nobel Prize in Pyhsics in 1903. His work consited of the studys of radiations which had just been discovered by Rontgen and his x-ray. He showed that the rays emitted by uranium caused gases to ionize and that they were different form those in x-rays because they could be deflected by electric and magnetic fields. He was award half of the noble prize for the dicovery of spontaneous raidoactivity.



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__**WILHELM C. ROENTGEN**__ Wilhelm C. Roentgen was born on March 25, 1845 in Russia and died on Feburary 10, 1923. Wilhelms biggist discovery was the x-ray and it is still used today all over the world in every hospital. He came about the dicovery of e-rays from his studies on cathod rays, when one night he was doing experiments and came across some form of rays that were very foreign to him, he called them x-rays. He found out that theses rays allowed him to see the bones that lied underneath the skin, he tryed this out on his wifes hand and found that he could see the bones that made up her hand.



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__**1875-1900**__

__**ERNEST RUTHERFORD**__ Enerest Rutherford was born in New Zeland on August 30, 1871 and died on October 19, 1937. He came up with the nucleus of an atom. He did this by scattering of the alpha rays in the inner structure of the atom. He also proposed that most of the mass in the atom was a positive charge and that it was concentrated in a minute space at the center of the atom. Rutherford also came up with the electron cloud model from his dicoveries of the positive charge in the center of the atom. Rutherford was most know for was his gold foil experiment where he fired small particles into a thin peice of gold. What he found was that the particle didnt go right through instead it bounced of in every direction and that some would even come shooting right back at him from this he proposed that the atom was made mostly of empty space.



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__**MARIE CURIE**__ Marie Curie was born in Poland on November 7, 1867 and died on July 4, 1934. In 1895 she married Pierre Curie, a professor in physics. In the year 1906 Pierre died. In 1914 she was the director of a laboratory in which she discovered two radioactive elements; polonium and radium. She did this by isolating the radioactive isotopes. Her accomplishments are still used today as radium is used in radiology which treats tumors. She had shown that the radiation was not the outcome of some interaction of molecules, but it comes from the atom itself. This was probably the most important thing that Curie constructed. []

__** ROBERT MILLIKAN **__

Robert Millikan was born in America on March 22, 1868 and died on December 19, 1953. He was a experimental physicist that measured the charge of the electron and his work on the photoelectric effect. He did this by his oil drop experiment at the University of Chicago. He got his Ph.D. for his work and research on the polarization of light emitted by incandescent surfaces.

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__** 1900-1915 **__

**__NEILS BOHR__**

Neils Bohr was born in Copenhagen on October 7, 1885 and died on November 18, 1962. In 1913 Bohr published a theory of the structure of the atom based on the work of Rutherford. Bohr suggested that the electrons in orbit around the nucleus of an atom moved in set orbitsof succesively increasing sizes. Bohr also stated that the outer most orbits of and atom couldhold more electrons than those of the inner ones and also determined the chemical properities of the atom.

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**__JJ THOMSON__**

JJ Thomson was born in Manchester, England on December 18, 1856 and died on August 30, 1940. He is credited for the discovery of the electron and of isotopes, and the invention of the mass spectrometer.Thomson discovered the electron through a series of experiments for the studying of the nature of electric discharge in a high vacum cathode ray tube. Thomson was awarded the 1906 Nobel Prize in Physics for the discovery of the electron and for his work on the conduction of electricity in gases. He determined that there were bodies much smaller than atoms and he was able to make cacluations on this and was able to determine the charge from his findings. From this he created the plum pudding model which was a sphere of positive matter with electrons scattered through out it with a negitive charge.



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**__ERWIN SCHRODINGER__**

Erwin Schrodinger was born in Austria on August 12, 1887 and died January 4, 1961. He was an Austrian theoretical physicist who recieved the Noble Prize in Physics in 1933. Schrodinger contributed to the way theory of matter and other fundamentals of quantum mechanics. He found out that when Frequency and wavelenght were put in to the general wave equations that it now became possible to express energy and momentum as a wave function. The wave mechanics were used to mathmatically describe the behavior of the electrons and atoms. His equation was found to be a lot easy to use then what people frist thought of it.



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**__1915-1950__**

**__JAMES CHADWICK__**

James Chadwick was born in England on October 20, 1891 and died on July 24, 1974. He was an English Nobel Laureate in physics awarded for his discovery of the neutron in the atom. Chadwick discovered the neutron and cleared up a lot of unanswered questions about the atom and the charges that were inside of it, he was also able to come up with a more improved model of the atom. Chadwick was able to make this discovery by the experiments using alpha particles and elements of beryllium and hydrogen useing the alpha particle and smashing it into the two elements. The results showed proof that there was a release of massive neutral particles, he later went on to call it a neutron. After receving the noble prize he went on to work with the british on there atomic bomb project during world war ll, he was also a advisor during the Manhattan Project which truned out to be the first atomic bomb made. []

__**WERNER HEISENBERG**__

Werner Heisenberg was born on December 5, 1901 in Würzburg and died in the year 1976. He was the son of Dr. August Heisenberg and his wife Annie Wecklein. Heisenberg's name will always be associated with his theory of quantum mechanics, published in 1925. Later Heisenberg stated his famous principle of uncertainty, which lays it down that the determination of the position and momentum of a mobile particle necessarily contains errors the product of which cannot be less than the quantum constant h and that, although these errors are negligible on the human scale, they cannot be ignored in studies of the atom. In 1932 he explained the principle of isotopic spin (isospin), a quantum number which arises from regarding different members of a charge multiplet as different states of a single particle. During World War II he led Germany's failed efforts to develop an atomic bomb.

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__**GERHARD HERZBERG**__ Gerhard Herzberg was born in Germany on December 25, 1904 and died on March 3, 1999. He was a pioneering physicist and physical chemist who won the Noble Prize for Chemistry in 1971. He fled to Canada in 1935 where he continued his distinguished scientific career. Herzberg was a german chemist who recieved a Nobel Prize in 1971 for his ideas on atomic and molecular spectroscopy in determining thestructures of diatomic and polyatomic molecules. He also perform chemical analysis on astronomical objects furthering research in the understanding of space.



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__**MODELS**__

**__SMALL, SPHEREICAL, SOLID, INDIVISIBLE MODEL__**



Developed by Democritus, this is the most basic model of the atom. He was right on a few things about the atom. First, it is very small. Second it is a sphere shape not a circle. Third is that the atom was solid which he was wrong about. Indivisible is the last property, this is mostly true although you can get rid of electrons.

__**ELECTON CLOUD MODEL**__

The cloud model represents a sort of history of where the electron has probably been and where it is likely to be going. The red dot in the middle represents the nucleus while the red dot around the outside represents an instance of the electron. Imagine, as the electron moves it leaves a trace of where it was. This collection of traces quickly begins to resemble a cloud. The probable locations of the electron predicted by Schrödinger's equation happen to coincide with the locations specified in Bohr's model.

__**PLUM PUDDING MODEL**__

The Plum Pudding model was made by JJ Thomson. There was no centralized mass. There was plums and pudding in every model. The Plums were used to shot the negatively charged electrons and the pudding was used to show a positively charged solution surrounding the plums. The plums were stationary. This was a major advancement in the structure of an atom.

__RUTHERFORD-BOHR MODEL__


This model came into existence through the Rutherford experiment where Rutherford shot charged particles at a gold foil which made him discover that many charged particles pass straight through while some bounced off at random angles. This model shows Rutherford's theory that an atom is mostly empty space due to electrons orbiting a small dense nucleus rather than a mass of plum pudding. In the Rutherford-Bohr model it is designed so that the nucleus is the core of the atom and the electrons move outside of the core. The core or the nucleus is made up of protons and neutrons.

__** PLANETARY MODEL **__



This model was developed by Bohr and is also known as the Bohr model. In the Bohr Model the neutrons and protons occupy a dense central region called the nucleus, and the electrons orbit the nucleus much like planets orbiting the Sun. The radius of the nucleus is about 100,000 times smaller than the radius of the entire atom, and as far as we can tell electrons are point particles without a physical extent.