422-004+M.+Morris+&+S.+Goose+Big+Timeline+Project

=__**THE HISTORY OF THE ATOM**__= By M. Morris & S. Goose (422-004)


 * Overview of Scientists:**
 * 1) **Democritus** (~ 470 to 380 B.C.)
 * 2) **Aristotle** (384 B.C. to 322 B.C.)
 * 3) **John Dalton** (1766-1844)
 * 4) **Wilhelm Conrad Roentgen** (1845-1923)
 * 5) **Henri Becquerel** (1852-1908)
 * 6) **J.J. Thomson** (1856-1940)
 * 7) **Madam Curie** (1867-1934)
 * 8) **Robert Millikan** (1868-1953)
 * 9) **Ernest Rutherford** (1871-1937)
 * 10) **Erwin Schroedinger** (1877-1961)
 * 11) **Niels Bohr** (1885-1962)
 * 12) **James Chadwick** (1891-1974)
 * 13) **Werner Heisenberg** (1901-1976)
 * 14) **J. Robert Oppenheimer** (1904-1967)
 * 15) **Hans Geiger** (1822-1945)

=**__Democritus__**=


 * Date of birth:** ~470 BC
 * Date of death:** ~380 BC
 * Country of Origin:** Abdera, Thrace (Greece)
 * Year of discovery:** Unknown
 * Contribution:** Democritus supported the idea that things could not be divided forever. He argued that existing nature did not have a beginning; was everlasting, had no voids, and had motion. Democritus supposed that atoms are impenetrable and that they had a density proportional to their volume. He observed the difference between primary motion and its secondary effects, which are impulse and reaction. This to Democritus was the law of necessity. He believed the world we see today was a result of an endless assortment of falling atoms. Democritus also believed that humans consisted of circular atoms of fire, which gave humans the ability to move their bodies. Democritus hypothesized that external objects gave off images which makes an impression on the human senses.

=__**Aristotle**__=
 * Date of birth:** ~384 BC
 * Date of death:** March 7, 322 BC
 * Country of Origin:** Greece
 * Year of discovery:** Unknown
 * Contribution:** During Aristotle’s time, it was believed that the atom was the smallest part of a substance and could not be divided. Aristotle disagreed with this idea. Instead he proposed that matter was made up of four main elements: Fire, Earth, Air, and Water. He believed that these elements allowed substances to interact with each other. For an example, elements cause substances to sink or float on water, air bubbles in liquids to float up, rain to fall, and fire to rise. Another idea that Aristotle proposed was that an element can be divided an infinite number of times.

=__**John Dalton**__=
 * Date of birth:** 1766
 * Date of death:** 1844
 * Country of Origin:** England
 * Year of discovery:** between 1808 and 1827
 * Contribution:** Dalton said that atoms of same kind and those in a mixture were different in weight. He calculated atomic weight from compounds to determine the likely structure of a compound. He also said that if two elements combine, the combinations will occur in a set sequence. Dalton believed an atom was just a small

object with nothing in it.

=__**Wilhelm Conrad Roentgen**__=
 * Date of birth:** March 27, 1845
 * Date of death:** February 10, 1923
 * Country of Origin:** Germany
 * Year of discovery:** 1895
 * Contribution:** Roentgen was interested in radiation coming from cathode-ray tubes. He noticed that the object next to it was glowing green. After intense research he called the new radiation x-rays. He realized that he was able to use it to take pictures of things. He used his wife's hand to produce the first x-ray image.

=__**Henri Becquerel**__=
 * Date of birth:** December 15, 1852
 * Date of death:** August 25, 1908
 * Country of Origin:** France
 * Year of discovery:** 1896
 * Contribution:** Becquerel researched a possible connection between x-ray and the occurring phosphorescence. He put uranium salt next to a plate covered with paper. The plate then became fogged up. He realized that rays were coming from the uranium and realized these were different from the x-rays. He won the Nobel Prize in 1903.

=__**J.J. Thomson**__= He won the Nobe Prize in 1906.
 * Date of birth**: December 18, 1856
 * Date of death:** 1940
 * Country of Origin:** England
 * Year of discovery:** 1897
 * Contribution:** When Thomson was studying cathode rays, he made a very important discovery, electrons. He estimated the number of them in am atom. He believed an atom was just a small object floating in the atoms. Realizing they were negative charged he modeled a primitive outline of an atom called the Plum Pudding model.

=__**Mare Curie**__= She became the first woman to be General Physics of Faculty of Sciences. She isolated polonium and called the new element radium after Poland. She also separated radium from radioactivity allowing her to study it. She received a Nobel Prize in 1903 and 1911 the second being for chemistry.
 * Date of birth:** November 7, 1867
 * Date of death****:** July 4, 1934
 * Country of Origin****:** Poland
 * Contribution:** Curie was a pioneer in that she was the first respected female scientist.

=__**Robert Millikan**__=
 * Date of birth:** March 22, 1868
 * Date of death:** December 19, 1953
 * Country of Origin:** USA
 * Contribution:** Millikan discovered the charge carried by electrons. Millikan stated that this charge was constant in all electrons. This led to the discovery of the electrical field in an atom. He also expanded the ultraviolet ray spectrum. Won the Nobel Prize for Physics in 1923.

=__**Ernest Rutherford**__=
 * Date of birth****:** August 20, 1871
 * Date of death:** October 19 1837
 * Country of Origin:** New Zealand
 * Contribution:** Rutherford studied ions in x-rays as well as electrical field. He discovered that radioactivity was atomic, not molecular. His greatest contribution was the discovery of nucleus in 1910. He decided that all the positive charges in a atom were in one area--the nucleus. He won a Nobel Prize in chem in 1908.

=__**Niels Bohr**__= able to make an model of the atom, a planetary model, setting the groundwork for the atomic model we use today. In 1922 he won the Nobel Prize for his work on the atomic structure.
 * Date of birth:** October 7,1885
 * Date of death:** November 18, 1967
 * Country of Origin:** Denmark
 * Contribution:** Bohr worked with Rutherford. Based upon Rutherford's nucleus ideas, Bohr was

=__**Erwin Schroedinger**__=
 * Date of birth****:** August 12,1887
 * Date of death:** January 4, 1961
 * Country of Origin:** Austria
 * Contribution:** Talk about a physics guy! He didn't like Bohr's atomic model so he came up with some of his own ideas about the atomic structure. But he was best known for his work in quantum mechanics. He won the Nobel Prize in Physics for this in 1933. Real time Occurrence: Burr! Its cold in here, there must be a Cold War in the atmosphere! During the 1950s America was in a psychological war with the Soviet Union.

=__James Chadwick__=
 * Date of birth:** October 20, 1891
 * Date of death:** July 24, 1974
 * Country of Origin:** England
 * Contribution**: Chadwick was a pretty neutral guy... until he proved the existence of neutrons in 1932! He said that the electrical field in the nucleus was caused by something, and that thing was neutrons. He led the way for uranium and atomic weaponry with his discovery!

=__Werner Heisenberg__=


 * Date of birth:** December 5, 1901
 * Date of death:** February 1, 1976
 * Country of Origin:** Germany
 * Contribution**: He believed that we can't assign an electron a position in space, that you had to follow its orbit to understand how it operated. Therefore we cannot assume Bohr's model is correct. He also made the principle of uncertainty, a law relating to the uncertainty of particles position and motion.

=Robert Oppenheimer= Date of Death: February 18, 1967** Contribution:**
 * Date of Birth: April 22, 1904
 * Country of Origin: USA

of government favor for his possibly Communist beliefs.**
 * He was the maker of the atomic bomb. His work led to the deaths of thousands but he saved our country.**
 * He eventually regretted his decision and fell out

=Hans Geiger= Date of Death: September 24, 1945** Contribution:He is best known for discovering the atomic nucleus. He did this by doing an experiment called the Geiger Marsden Experiment.**
 * Date of Birth: September 30, 1882
 * Country of Origin: Germany

=__Atom Models__=

**1) Small, Spherical, Solid, Invisible Model**

 * Date Developed:** unknown
 * Explanation:** This model is the most basic model of the atom. During Ancient Greece, many great thinkers developed an idea what the atom looked like. They came up with the idea that if you cut up an object an infinite times, that the smallest unit of that object would be the atom.

**2) Electron Cloud Model**

 * Date Developed:** 1920
 * Explanation:** This model contained nucleus made up of protons and neutrons. The protons and neutrons are surrounded by electrons that are in clouds at different energy levels.

3) Plum Pudding Model

 * Date Developed:** 1904
 * Explanation:** This model shows that the atom is surrounded by electrons. Surrounding the electrons is a positive charge. The positive charge balances out the negative charge from the electrons. The reason why this model is called the "Plum Pudding" model is because the electrons resemble plums and the positive charge is resembled by the surrounding pudding.

4) Rutherford-Bohr Model

 * Date Developed:** 1913
 * Explanation:** The Rutherford-Bohr model was proposed by Niels Bohr. This model was actually an improvement to the Rutherford model. This model introduced the idea that electrons traveled around the nucleus with different energy levels. This idea was called fixed orbits. This model also introduced that electrons can move to higher energy levels during a small period of time.

5) Planetary Model

 * Date Developed:** 1915
 * Explanation:** This model shows neutrons and protons in the nucleus of an atom. The electrons travel around the nucleus.

=__World Events__=

1) First Dynasty of Egypt is formed - 3000 BC 2) Great Wall of China was finished during the Ming Dynasty - 220 BC 3) Julius Caesar was assassinated by a group of conspirators - 44 BC
 * Ancient**

1) The printing press was invented by Johannes Guttenberg - 1450 2) America became a nation - 1776 3) The French Revolution ended and France became a monarch-free nation - 1789
 * 500-1800**

1) George Stephenson developed the Steam Engine - 1814 2) The War of 1812 ended - 1815 3) The American Civil war ended - 1865
 * 1800-1875**

1) Telephone was invented by Alexander Graham Bell - 1876 2) The Triple Alliance was formed (Germany, Italy, and Austria)- 1882 3) Vincent Van Gogh committed suicide - 1890
 * 1875-1900**

1) Australia was formed as an nation - 1901 2) Japan annexes Korea - 1910 3) Archduke Ferdinand Assassinated - 1914
 * 1900-1915**

1) World War I ended - 1918 2) Empire State Building Opened - 1931 3) First Electronic Computer - 1946
 * 1915-1950**

1) Kenya becomes independent - 1963 2) Apollo 11 was launched - 1970 3) Iraq War began - 2003
 * 1950-current**

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