422-004+R.+Maguire+Timeline+project


 * A BRIEF HISTORY OF THE atomic theory**

by Renato Maguire

From Democritus to plum pudding to present.

**Democritus** (about 470-380 BC) While Democritus' more in-depth findings on the atom are now largely considered incorrect, he is massively important for the sole reason of being the first to recognize the concept of the atom. As a student of the great philosopher Leucippus he expanded on his teacher's atomic findings. He held a wide variety of mostly discredited ideas but his importance to chemistry and science in general cannot be understated.

470 BC - The construction of the Temple of Zeus begins.

380 BC - Darius III of Persia is born.

400 BC - The catapult is invented.

**Aristotle** (384 BC-322 BC) A famous Greek philosopher, Aristotle studied virtually every available topic there was to study in his day. Working with fields as broad as government and education as well as scientific fields like chemistry, he made many contributions to the liberal arts. He was a student of Plato and played a very important part in ancient philosophy. However, many of his writings were lost after he died in 322 BC.

//Major World Event: Corinthian War. An ancient Greek conflict lasting from 395 BC until 387 BC. Sparta against Athens, Corinth, Argos, and Thebes.//

**John Dalton** (1766-1844) John Dalton was an English chemist who spent most of his academic career studying atomic theory and working with colour blindness. Dalton was massively important in intensely studying the atom, how it works, and what it is made up of. The atomic theory, which Dalton's name is commonly associated with, states that all matter is made up of atoms and that atoms are both indivisible and indestructable. These ideas that Dalton pioneered have remained fundamentally unshaken despite all of the progress made since the time of Dalton's death, though it is generally now believed that atoms can in fact be subdivided and destroyed.

1780 - The Battle of Cape_St. Vincent, Revolutionary War.

1830 - Alexandrite is discovered. It is a form of the mineral chrysoberyl.

1843 - The first issue of "The Economist" is published.

**Wilhelm Conrad Röntgen** (1845-1923)

Wilhelm Conrad Rontgen was an important man. Not only did he win the first Nobel Prize in Physics in 1901, but he also had an element (re)named after him. He contributed greatly to the development of x-ray technology and also worked with electromagnetic radiation. Rontgen's very first X-ray was of his wife's hand, and it rightfully scared her half to death. Fun fact: X-rays are also known as "Röntgen rays".

//Major World Event: World War I. 1914 to 1918. Entente Powers, such as United States, Russia, and the United Kingdom, verses the Central Powers, such as the Germans and the Ottoman empire.//

1889 - The Eiffel Tower is completed in Paris, France.

1902 - The first ever movie theater in the United States opens. It is dubbed the "Electric Theatre."

**Henri Becquerel** (1852-1908)

Henri Becquerel was a French physicist who is commonly credited as one of the first discoverers of radioactivity. He had been studying Wilhelm Rontgen's work, and was investigating phosphorus in uranium salts, when he managed to "accidentally" discover radioactivity. He used photographic plates that helped to show the radiation that occurred from the uranium salts. In 1903 he shared a Nobel Prize in Physics with Marie and Pierre Curie.

**J.J. Thompson** (1856-1940) The famed inventor of the "plum pudding model" of the atom, J.J. Thompson was critical in many immensely important discoveries in the fields of science and physics. He is credited for the discovery of isotopes and the electron as well. Born in England, he studied at the University of Manchester and was awarded the Nobel Prize in Physics in 1906. His discovery of electrons stemmed from his work with cathode ray tubes in three separate experiments. He also proved the hydrogen only has a single electron, something that was not known at the time.

This image demonstrates Thompson's plum pudding model:



1939 - The Invasion of Poland carried out by German forces.

1918 - The Finnish Civil War begins (and ends).

1921 - The United States declares a peace with Germany, ending World War I.

**Marie Curie** (1867-1934)

Marie Curie, or alternatively "Madam" Curie, was a Polish physicist who made important contributions to the fields of radioactivity and chemistry. The very radioactive element Polonium was discovered by Marie and her husband, Pierre. She was awarded the Nobel Prize in Physics in 1903, and is famous not only for her discoveries relating to science but also for her gender.

**Robert Millikan** (1868-1953)

Robert Millikan was an American physicist who is probably best remembered for his work on measuring the charge of the electron. He received his Ph.D from Columbia University and soon went to work on studying electrons. In 1909 he began working on the famous "oil-drop" experiment, in which he attempted to measure the charge of a single electron. Later in life he studied cosmic rays and the "photoelectric effect". He was awarded the 1923 Nobel Prize in Physics for his seminal work.

The 1940s - World War II rages until 1945.

1941 - The first ever jeep is produced.

**Ernest Rutherford** (1871-1937)

Ernest Rutherford, or "Lord" Rutherford as he is sometimes called, was a Scottish physicist who is now commonly regarded as the father of nuclear physics. He directed the "gold foil experiment", which proved J.J. Thompson's plum pudding model of the atom to be erroneous. Many Nobel Prizes were given to his "students", and he was knighted in 1914. Without his research in the field of nuclear physics, the Manhattan project would not have been possible.

**Erwin Schrödinger** (1877-1961)

Erwin Schrödinger was an Irish physicist who was instrumental to the development of quantum mechanics. He is also famous for the thought experiment he proposed, Schrödinger's cat, which was intended to show the strangeness of quantum mechanics. In his personal life, Albert Einstein and Erwin were great friends and the two of them worked together extensively, Einstein being the one who suggested the "cat" portion of the "Schrödinger's cat" experiment. He was awarded the Nobel Prize in Physics in 1933. He also worked in scientific fields relating to color.

1952 - Operation Ivy, the first hydrogen bomb ever detonated by the United States.

1961 - John F. Kennedy becomes president of the United States.

1956 - Morocco becomes independent from France.

**Niels Bohr** (1885-1962) The man, the myth, the proposer of the Bohr model. Niels Bohr was a Danish-born physicist who made highly important contributions to the field of quantum mechanics. He also tore apart and reconstructed our prior knowledge of what the atom looked like and how its inner workings behaved. The Bohr model of the atom described the atom as a small nucleus with a positive charge, surrounded by orbiting electrons. Building on top of the knowledge bestowed upon him by other scientific innovators he was able to suggest a deeply complicated yet at the same time simple and easy to understand model of the atom. Of course he had to have the model named after him. He received the Nobel Prize in Physics in 1922 for his monumental works.

//A Bohr model of the atom.//

**James Chadwick** (1891-1974) Chadwick was a special guy. He was special because he discovered the neutron. He was also special because he won a Nobel Prize in 1935 for it. The English born physicist studied at the University of Cambridge and discovered that there were particles inside of the nucleus of an atom that had no charge. Thus, they he decided to call them neutrons. His discovery paved the way for other scientific exploration in that it allowed elements that were heavier in mass than uranium to be created in the laboratory.

1936 - The Hoover Dam opens after after 5 years of construction.

1911 - Chevrolet is founded.

1923 - Yankee Stadium opens in The Bronx after a year of construction.

**Werner Heisenberg** (1901-1976)

Werner Heisenberg was a German physicist who is famous for being one of the founders of quantum physics and also for being the head of the German nuclear energy project, which was a collective attempt by Nazi scientists during World War II to develop a practical atomic bomb. He also proposed the Heisenberg uncertainty principle, which relates to quantum physics. He was awarded a Nobel Prize in Physics in 1932. As Germany slowly became a dictatorship in the late 1930s and 1940s, Heisenberg was forced to work under the leadership of Adolf Hitler, though many speculate that he was loyal to Germany but not to the Nazi regime.

//World Event: World War II, Nazi Germany. 1940s, atomic bomb research under the rule of Adolf Hitler.//

**Robert Oppenheimer** (1904-1967)

J. Robert Oppenheimer was an American theoretical physicist who greatly contributed to the development of the atomic bomb during World War II. He played a critical part in the infamous Manhattan project and came to regret his research during this perioid after he witnessed the devastating power of nuclear weapons on Hiroshima and Nagasaki. He was awarded the Enrico Fermi Award by president John F. Kennedy after World War II ended. Despite this Oppenheimer still felt guilt for his part in the Manhattan project nearly two decades after the war ended.

1963 - President John F. Kennedy is assassinated.

1965 - Malcolm X is killed by assassins.

1968 - The musical "Hair" hits Broadway for the first time.

**Hans Geiger** (1882-1945)

Hans Wilhelm Geiger was a German physicist who is best remembered today for his part in the Geiger Marsden experiment, which led to the discovery the atomic nucleus. He worked with Ernest Rutherford at the University of Manchester and also co-invented the Geiger counter, which is a machine designed to count alpha particles. During World War II he participated in German attempts to create an atomic bomb.

**Ernest Marsden** (1889-1970)

Ernest Marsden was a British physicist who played the other half in the Geiger-Marsden experiment, which as stated previously led to the discovery of the atomic nuclear. He attended the University of Manchester where he met Ernest Rutherford and became friends with him. He died in Wellington Bay in 1970.

1972 - Apollo 16 is launched.

1979 - Sheldon Lee Glashow wins the Nobel Prize in Physics for his research on electroweak interaction.

1971 - Apollo 14 lands successfully on the moon.

In this timeline I attempted to show the progress made from century to century dealing with the history of the atom and the scientists who made academic history working in the fields of physics and chemistry. I also attempted to relate world events to certain scientists who worked in time periods affected by these events.

Renato Maguire

http://www.iep.utm.edu/d/democrit.htm http://www.iep.utm.edu/a/aristotl.htm [] http://nobelprize.org/nobel_prizes/physics/laureates/1901/rontgen-bio.html http://www.chemheritage.org/classroom/chemach/atomic/thomson.html http://nobelprize.org/nobel_prizes/physics/laureates/1903/becquerel-bio.html http://nobelprize.org/nobel_prizes/physics/laureates/1903/marie-curie-bio.html http://nobelprize.org/nobel_prizes/physics/laureates/1933/schrodinger-bio.html http://csep10.phys.utk.edu/astr162/lect/light/bohr.html http://www.thocp.net/biographies/chadwick_james.htm http://www.atomicarchive.com/Bios/Oppenheimer.shtml http://nobelprize.org/nobel_prizes/physics/laureates/1932/heisenberg-bio.html http://www.atomicarchive.com/Images/bio/H07.jpg http://www.phy.bg.ac.yu/web_projects/giants/geiger.html http://www.eequalsmcsquared.auckland.ac.nz/sites/emc2/tl/atomic-physics/articles/sir-ernest-marsden--a-remarkable-life-in-science.cfm
 * References**