Marshall.Caruso.atomic.timeline


 * __Ancient Times__, (450 AD and prior)**



Democritus (ca.460BC– ca. 370 BC) was an Ancient Greek philosopher born in Abdera, Thrace,Greece.He was an influential pre-Socratic philosopher and pupil of Leucippus, who formulated an atomic theory for the cosmos. His exact contributions are difficult to disentangle from his mentor Leucippus, as they are often mentioned together in texts. Their speculation on atoms, taken from Leucippus, bears a passing and partial resemblance to the nineteenth-century understanding of atomic structure that has led some to regard Democritus as more of a scientist than other Greek philosophers; nevertheless their ideas rested on very different bases.Largely ignored in Athens, Democritus was nevertheless well-known to his fellow northern-born philosopher Aristotle.Platois said to have disliked him so much that he wished all his books burned Many consider Democritus to be the "father of modern science".



We know almost nothing about Thales of Miletus. Later generations told many anecdotes about this wise man, but it is difficult to verify the reliability of these stories. What seems certain is that he predicted the solar eclipse of 28 May 585, which was remembered because the Lydian king Alyattes and the Median leader Cyaxares were fighting a battle on that day. Another reliable bit of information is that he did some geometrical research, which enabled him to measure the pyramids. However, his most important contribution to physics and philosophy is his attempt to give non-religious, rational explanations for physical phenomena. Behind the phenomena was not a catalogue of deities, but one single, original principle. Although his hypothesis that this principle was water is rather unfortunate, his idea to look for deeper causes was the true beginning of philosophy and science.

Knowledge of Democritus’ life is largely limited to untrustworthy tradition: it seems that he was a wealthy citizen of Abdera, in Thrace; that he traveled widely in the East; and that he lived to a great age. According to Diogenes Laërtius, his works numbered 73; only a few hundred fragments have survived, mostly from his treatises on ethics.

Aristotle of Stagira

The most famous student of the Athenian philosopher Plato was the Macedonian scientist Aristotle of Stagira (384-322). After the death of his master, he studied biology and accepted a position as teacher of the Macedonian crown prince Alexander. When the Macedonians subdued Greece, Aristotle founded a school at Athens. Most of his writings are lost; what remains are his lecture notes, which were rediscovered in the first century BCE. During the last decades, scholars have started to re-examine the fragments of the lost works, which has led to important changes in our understanding of Aristotle's philosophy. However, the accepted view remains that he replaced his master's speculations with a more down-to-earth philosophy. His main works are the Prior Analytics (in which he described the rules of logic), the Physics, the Animal History, the Rhetorics, the Poetics, the Metaphysics, the Nicomachean Ethics, and the Politics. All these books have become classics, and it is not exaggerated to say that Aristotle is the most influential philosopher of all ages and the founder of modern science.

__**1700-1800**__

Benjamin (1706-1790) Was the first great American scientist as well as a great statesman and diplomat, suggested, in the 1740's, that there was a single electrical fluid. When a substance contained a greater than normal quantity of electric fluid, it possessed one kind of electric charge; when it contained a less than normal quantity, it possessed the other kind.


 * **Joseph Black
 * **Joseph Black

Another important step forward was taken by a Scottish chemist, Joseph (1728-1799). The thesis that earned him a medical degree in 1754 dealt with a chemical problem(this was the era when mineralogy and medicine were closely intertwined), and he published his findings in 1756. What Black did was to heat, strongly, the mineral limestone calcium carbonate). This carbonate decomposed, giving off a gas and leaving behind lime (calcium oxide). The gas given off could be made to recombine with calcium oxide to form calcium carbonate again. The gas itself (carbon dioxide) was identical with Van Helmont's "gas sylvestre", but Black called it "fixed air" because it could be combined ("fixed") in such a way as to form part of a sold substance.


 * James Watt**

James Watt, the son of a merchant, was born in Greenock, Scotland, in 1736. At the age of nineteen Watt was sent to Glasgow to learn the trade of a\ mathematical-instrument maker. After spending a year in London, Watt returned to GGlasgow in 1757 where he established his own instrument-making business. Watt soon developed a reputation as a high quality engineer and was employed on the Forth & Clyde Canal and the Caledonian Canal. He was also engaged in the improvement of harbours and in the deepening of the Forth, Clyde and other rivers in Scotland. In 1763 Watt was sent a Newcomen steam engine to repair. While putting it back into working order, Watt discovered how he could make the engine more efficient. Watt worked on the idea for several months and eventually produced a steam engine that cooled the used steam in a condenser separate from the main cylinder. James Watt was not a wealthy man so he decided to seek a partner with money. John Roebuck, the owner of a Scottish ironworks, agreed to provide financial backing for Watt's project. When Roebuck went bankrupt in 1773, Watt took his ideas to Matthew Boulton, a successful businessman from Birmingham. For the next eleven years Boulton's factory producing and selling Watt's steam-engines. These machines were mainly sold to colliery owners who used them to pump water from their mines. Watt's machine was very popular because it was four times more powerful than those that had been based on the Thomas Newcomen design. Watt continued to experiment and in 1781 he produced a rotary-motion steam engine. Whereas his earlier machine, with its up-and-down pumping action, was ideal for draining mines, this new steam engine could be used to drive many different types of machinery. Richard Arkwright was quick to importance of this new invention, and in 1783 he began using Watt's steam-engine in his textile factories. Others followed his lead and by 1800 there were over 500 of Watt's machines in Britain's mines and factories.

__**1800-1875**__ John Dalton FRS (6 September 1766 – 27 July 1844)
 * John Dalton**

John Dalton (1766–1844) was born into a modest Quaker family in Cumberland, England, and earned his living for most of his life as a teacher and public lecturer, beginning in his village school at the age of 12. After teaching 10 years at a Quaker boarding school in Kendal, he moved on to a teaching position in the burgeoning city of Manchester. There he joined the Manchester Literary and Philosophical Society, which provided him with a stimulating intellectual environment and laboratory facilities. The first paper he delivered before the society was on color blindness, which afflicted him and is sometimes still called “Daltonism.”

Dmitri Ivanovich Mendeleev was a Russian chemist and inventor. He is credited as being the creator of the first version of the periodic table of elements. Using the table, he predicted the properties of elements yet to be discovered. __**1875-1900**__
 * Dmitri Mendeleev**

**Ernest Rutherford**

Born on a farm in New Zealand, Ernest Rutherford (1871–1937) was responsible for a remarkable series of discoveries in the fields of radioactivity and nuclear physics. He discovered alpha and beta rays, set forth the laws of radioactive decay, and identified alpha particles as helium nuclei. Most important, he postulated the nuclear structure of the atom: experiments done in Rutherford's laboratory showed that when alpha particles are fired into gas atoms, a few are violently deflected, which implies a dense, positively charged central region containing most of the atomic mass.

**William C. Roentgen**

Wilhelm Conrad Röntgen (27 March 1845 – 10 February 1923) was a German physicist, who, on 8 November 1895, produced and detected electromagnetic radiation in a wavelength range today known as X-rays or Röntgen rays, an achievement that earned him the first Nobel Prize in Physics in 1901.


 * Henri Becquerel**

After Wilhelm Conrad Röntgen's discovery of x-rays, French physicist Henri Becquerel noted an unknown energy that was emitted from uranium salts. He left a rock and a well-wrapped photographic plate in his desk drawer and found later that the plate, though unexposed to light, had developed patterns which would ordinarily indicate exposure. Announced in 1896, he had accidentally discovered a new "penetrating ray" that came to be called radioactivity. Almost immediately thereafter, his student Marie Curieand her husband Pierre Curie showed that thorium also emitted what were then called Becquerel rays. Becquerel and the Curies shared the Nobel Prize in Physics in 1903.


 * 1900-1915**


 * ~ J. J. Thomson ||
 * = [[image:http://upload.wikimedia.org/wikipedia/commons/thumb/c/c1/J.J_Thomson.jpg/200px-J.J_Thomson.jpg width="200" height="313" link="http://en.wikipedia.org/wiki/File:J.J_Thomson.jpg"]] ||

Sir Joseph John "J. J." Thomson, (18 December 1856 – 30 August 1940) was a British physicist and Nobel laureate. He is credited for the discovery of the electron and of isotopes, and the invention of the mass spectrometer. 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.


 * Robert Millikan**



Robert A. Millikan (22 March 1868 – 19 December 1953) was an American experimental physicist, and Nobel laureate in physics for his measurement of the charge on the electron and for his work on the photoelectric effect. He served as president of Caltech from 1921 to 1945. He also served on the board of trustees for Science Service, now known as Society for Science & the Public, from 1921-1953.

Born in Warsaw, Poland in November 7, 1867
 * Marie Curie**

Marie Curie is best known as the discoverer of the radioactive elements polonium and radium and as the first person to win two Nobel prizes. For scientists and the public, her radium was a key to a basic change in our understanding of matter and energy. Her work not only influenced the development of fundamental science but also ushered in a new era in medical research and treatment.

Erwin Rudolf Josef Alexander Schrödinger 12 August 1887, Erdberg – 4 January 1961, Vienna) was an Austrian theoretical physicist who was one of the fathers of quantum mechanics, and is famed for a number of important contributions to physics, especially the Schrödinger equation, for which he received the Nobel Prize in Physics in 1933. In 1935, after extensive correspondence with personal friend Albert Einstein, he proposed the Schrödinger's cat thought experiment.
 * 1915-1950**
 * Erwin Schrodinger**

Born in Copenhagen, Denmark October 7, 1885. Died November 18,1962. In 1922 Bohr was the first to suggest that electrons inside an atom had a set distance away from the nucleous. He also theorized that if an atom gained energy, the electrons would jump one energy level farther from the nucleous. He also said that the same is true of the opposite. He said that if atoms radiate energy then the electrons are losing an energy level and getting closer to the nucleous. This theory was proven true by other scientists and in 1922 Niels Bohr recieved the Nobel Prize.
 * Niels Bohr**


 * James Chadwick**



Born in Cheshire, England on October 20, 1891, Died July 24, 1974. His major discovery came in 1932. The major discovery that James Chadwick made was the discovery of Neutrons. It had been theorized before that such things as nuetrons existed in an atom, Scientists believed there was probably a particle without any charge. Chadwick was able to prove through a series of tests that there was in fact nuetrons i the nucleous of an atom.

(1901-1976)
 * Werner Heisenber**

German physicist Werner Heisenberg studied under Max Born, David Hilbert, and Arnold Sommerfeld, and won the Nobel Prize for Physics in 1932. His 1925 theory of quantum mechanics offered a matrix method to explain stationary discrete energy states, and was soon superseded byErwin Schrödinger's more intuitive wave equation. Of more lasting impact was his 1927 uncertainty principle, which states that it is impossible to accurately measure both position and momentum (energy and time) concurrently, and that the more precisely we know an object's position the less precisely we can know its momentum, and vice versa. In 1932 he explained the principle

Small, spherical, solid, indivisible model

 Propsed by Democritus, one of the very first models of atoms created.

Electron Cloud Model The electron cloud model is an atom model wherein electrons are no longer depicted as particles moving around the nucleus in a fixed orbit. Instead, as a quantum mechanically-influenced model, we shouldn’t know exactly where they are, and hence describe their probable location around the nucleus only as an arbitrary ‘cloud '

Plum Pudding Model The Plum Pudding Model is an atom model proposed by JJ Thomson, the physicist who discovered the electron. It is also known as the Chocolate Chip Cookie or Blueberry Muffin Model. You can easily picture it by imagining the said goodies. For example, you can imagine a plum pudding wherein the pudding itself is positively charged and the plums, dotting the dough, are the negatively charged electrons.

Rutherford-Bohr Model

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.

Planetary Model

The Bohr Model is probably familar as the "planetary model" of the atom illustrated in the adjacent figure that, for example, is used as a symbol for atomic energy (a bit of a misnomer, since the energy in "atomic energy" is actually the energy of the nucleus, rather than the entire atom). In the Bohr Model the neutrons and protons (symbolized by red and blue balls in the adjacent image) occupy a dense central region called the nucleus, and the electrons orbit the nucleus much like planets orbiting the Sun (but the orbits are not confined to a plane as is approximately true in the Solar System). The adjacent image is not to scale since in the realistic case 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.

Works cited: [] [|http://www.chemheritage.org] [] [|www.wikipedia.org] [] [] [] [|http://csep10.phys.utk.edu] www.**universetoday**.com craigjm.tripod.com/physics.html