Berlin.timeline.fall.2011

**ANCIENT TIMES - 450 AD and Years Prior**

**Leucippus**


 * Born**: ~500 BCE
 * Died**: <500 BCE
 * Country of Origin**: Abdera/Miletus (Modern day Greece/Turkey)
 * Year of Discovery**: **(~500 BCE, <500 BCE]**

= =

Little is known about Leucippus, but he was the first person to propose that matter was made up of small, indivisible particles. His theory was called “Atomism”. His student and eventual successor was Democritus, who vastly expanded on Leucippus’s atomic theory. = =

**Democritus**

Year of Discovery: **(460BCE, <370 BCE]**
 * Born:** 460 BCE
 * Died:** 370 BCE
 * Country of Origin:** Abdera (modern-day Greece)

Democritus expanded upon an atomic theory brought forth by his mentor and teacher, Leucippus. He postulated that atoms were infinitely small particles that came together to form objects. To him, iron atoms were hard spikey balls with hooks on the end. Air atoms were light and wispy, salt atoms were sharp because of their taste, etc. In summary, it was the size, shape, color, and texture of the larger objects that dictated how the atoms looked and behaved. Democritus took a very practical approach to science, believing that all explanations of phenomena were able to be explained by physical means.

**Aristotle**


 * Born**: 384 BCE
 * Died**: 322 BCE
 * Country of Origin**: Chalkidiki (modern day Greece)
 * Year of Discovery**: **335-323 BCE**

Aristotle was undoubtedly one of the most famous people in civilization. He was a Physicist, Biologist, Mathematician, Psychologist and Philosopher who tutored Alexander The Great in 343 BCE. His crowning achievement was his scientific method derived through what he called “natural philosophy” (which to Aristotle meant the study of “natural things”, meaning science). As a biologist he was able to tell marine mammals apart from fish, sharks, and octo-pods (octopus, squid, etc).


 * 1700-1800 **

**Mikhail Vasilyevich Lomonosov**

**Born**: November 19th 1711 **Died**: April 15th 1765 **Country of Origin**: Russia **Year of Discovery**: **1745**- formed a list of 3000 minerals / froze mercury = =

As a physicist, Mikhail proposed the //wave theory of light//, and did experiments concerning the mass of burning metal in closed systems, which re-affirmed the Law of conservation of mass: “Today I made an experiment in hermetic glass vessels in order to determine whether the mass of metals increases from the action of pure heat… without access of air from outside the mass of the burnt metal remains the same”. As a chemist he made a list detailing 3000 minerals, and he was the first person to freeze mercury and record its properties

**Henry Cavendish**


 * Born**: October 10th 1731
 * Died**: Februrary 24th 1810
 * Country of Origin**: France
 * Year of Discovery**: **1785**- discovered the composition of the earth’s atmosphere
 * 1797**-Cavendish Experiment, conducted to determine the density of the Earth (was reasonably accurate)

Cavendish discovered Hydrogen gas by dissolving metals in acid. He was so intensely shy that he rarely published his findings, and it was later discovered that he had inferred or discovered “Richter's Law of Reciprocal Proportions, Ohm's Law, Dalton's Law of Partial Pressures, principles of electrical conductivity (including Coulomb's Law), and Charles's Law of Gases (Wikipedia)”. However, his lack of publishing made it possible for others to take credit for these discoveries.

**Antoine Lavoisier**


 * Born:** August 27th 1743
 * Died:** May 8th 1794
 * Country of Origin:** France
 * Year of Discovery**: **1779**-discovered the elements Oxygen and Hydrogen, and their role in the making of water / invented stoichiometry.

Lavoiser worked in the years running up to the French Revolution, and was eventually killed by beheading during the Reign Of Terror (1794) because he had belonged to a corrupt society of tax collectors known as the Ferme Générale (Farmer’s General). The wealth he gained from this society helped to fund his experiments.

Lavoisier was also the first person to propose the Law of Conservation of Mass, but did not conduct experiments to prove it. Antoine also was the first person to use stoichiometry by combining chemicals in equal ratios. He published the first textbook on chemistry in 1789 (Elementary Treatise on Chemistry) which included both his use of Stoichiometry and his Law of Conservation of Mass.

**1800-1875**

**John Dalton **


 * Born:** September 6, 1766
 * Died:** July 27, 1844
 * Country of Origin:** England
 * Year of Discovery: 1801-** Dalton’s 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 whole numbers.”**
 * 1808-** Published table of atomic weights (__“A New System of Chemical Philosophy”)__



Dalton was Quaker who was responsible for many scientific discoveries, from his research on color blindness in 1794, and his work on Gases (Dalton’s Law of Partial Pressures) in 1803, to his atomic theory and his book on atomic weights. He formulated the first list (not to be confused with table) of elements, along with their structures. He proposed that the atom was a solid sphere, which bonded with other atoms in fixed ratios. Atoms could be discerned from other atoms by their atomic weight.

......................................................................................................................................................................Also, he looks like Dr. Reich....................

**James Clerk Maxwell**


 * Born**: June 13th 1831
 * Died**: November 5th 1879
 * Country of Origin**: Scotland
 * Year of Discovery**: **1861**- First color photograph
 * 1865**- Discovered that electrical and magnetic fields travel through space as waves

James Maxwell contributed much in the establishing of a general understanding of Electromagnetic forces and how they behave. He published his textbook on electromagnetic forces in 1873, it was called “A Treatise on Electricity and Magnetism”. Albert Einstein said: “[His work was the] most profound and the most fruitful that physics has experienced since the time of Newton”.

He made the first color photograph by attacking red, green, and purple lenses on his camera. When these photos were developed, he superimposed them and the result was color photography.

** John James Waterston **


 * Born**: 1811
 * Died**: June 18th 1883
 * Country of Origin**: Scotland
 * Year of Discovery**: **1843**- Kinetic Gas Theory

James Waterson’s kinetic theory held that heat waves and heat radiation behave similarly to light waves. Eventually his work let him to propose the Ideal Gas Law, but it was never published at the time, with people calling it “nonsense”. Eventually the IGL would be re-discovered by James Clerk Maxwell and Rudolf Clausius. Waterson died when he fell into a canal and drowned, it is rumored to be because of heat stroke.

**Wilhelm C Rontgen**
 * 1875-1900 **


 * Born**: March 27th 1845
 * Died**: February 10th 1923
 * Country of Origin**: Germany
 * Year of Discovery**: **November 8th 1895** – discovered X-rays when charging a crookes tube with a Ruhmkorff coil and aiming it at a plate of barium platinocyanide.
 * 1901**- VERY FIRST Nobel Prize in Physics (“in recognition of the extraordinary services he has rendered by the discovery of the remarkable rays subsequently named after him”)

Rontgen dicovered X-rays by mistake, when he was preforming an experiment involving vacuum tubes. Barium platinocyanide glowed when put near his crooks tube. He later tested his wife's hand, placing it in front of the plates, and the first X-ray photograph was taken. Rontgen himself gave the name "X" to the rays, intending that the X would be replaced by something else.

Rontgen lived a surprisingly long life for a scientist who toyed with radiation. This is due to the fact that he properly shielded himself from the radiation using lead.

**Henri Becquerel**

**Born:** December 15, 1852 **Died:** August 25, 1908 **Country of Origin:** France **Year of Discovery:** **1896**-discovered radioactivity, spontaneous emission **1903**-Nobel prize in Physics, shared with Marie & Pierre Curie (“in recognition of the extraordinary services he has rendered by his discovery of spontaneous radioactivity”)

Becquerel was going to expose potassium uranyl sulfate to bright sunlight to see its phosphorescence. When he took out the exposure plates next to his sample, he discovered that they had already been exposed (i.e, already had the effect of being exposed to sunlight, even though they were out of the sun for a day). This led Becquerel to propose “spontaneous radioactivity”, for which he received a nobel prize.

**JJ Thomson**
 * Born**: December 18th 1856
 * Died**: August 30th 1940
 * Country of Origin**: United Kingdom
 * Year of discovery**: **1906**-Nobel prize in Physics

In 1897 Thomson used magnets to bend streams of partials emanating from Crookes (cathode-ray) tubes. He concluded that, because the beams bent toward a positively charged plate, the partials were negative. Thomson originally named these partials “corpuscles”, but future scientists called them electrons. This also gave birth to the “Plum-pudding” atomic model. In the Model, electrons are evenly distributed throughout a positively charged sphere, giving the atom a neutral charge. Running electricity through an atom would displace the electrons, giving the atom a charge.

**Marie Curie**
 * 1900-1915 **


 * Born**: November 7, 1867
 * Died**: July 4, 1934
 * Country of Origin**: Poland (Kingdom of Poland,1815-1867)
 * Year of Discovery**: **1903**-Nobel prize in Physics, shared with Pierre Curie and Henri Becquerel
 * 1911**-Nobel prize in Chemistry

 Marie Curie was the first woman to receive the Nobel prize, and is the ONLY woman (so far) to win 2 Nobel prizes. Curie coined the term Radioactivity when experimenting with Urainium's atomic properties and discovered that the radiation came from the atom and not from a reaction. Henry Becquerel discovered radioactivity, put was unable to determine where it came from, other than uranium salts. Curie and her husband also discovered 2 new elements: Polonium and Radium. During WW1, she proposed and advocated the use of Radium/Radon-powered Mobile X-ray devices during WW1. These devices were responsible for the saving of many lives, as doctors could now accurately diagnose a casualty.

Marie Curie died from radiation exposure (aplastic anemia) due to her lacking proper radiation protection. She would carry vials of radium in her pocket and show them to passerby, and store the vials in her desk.

**Robert Millikan**


 * Born:** March 22nd, 1868
 * Died:** December 19th, 1953
 * Country of Origin:** United States
 * Year of Discovery:** **1908**-Oil-drop experiment: discovered that charge of the electron (1.5924(17)×10−19 C)
 * 1923**- Nobel Prize in Physics

Millikan discovered the charge of an electron via his oil-drop experiment. His experiment consisted of two charged plates. Oil would be sprayed above the two plates into a chamber. The oil would fall down through a hole in the top (positively charged) plate. Then, “ionizing radiation” would be shot at a perpendicular angle to the falling oil, and a high voltage would be applied to the plates. Using a microscope, Millikan could see that the oil drops hung in suspension when struck by the radiation. Using complicated math, Millikan discovered the charge of an electron by adjusting the voltage of the charged plates (1.5924(17)×10−19 Coulombs

**Ernest Rutherford**


 * Born**: August 30th 1871
 * Died**: October 19th, 1937
 * Country of Origin**: New Zealand
 * Year of Discovery**: **1899**-Defined/discovered Alpha/Beta/Gamma rays
 * 1908**-Nobel Prize in Chemistry
 * 1911**- Proposed Rutherford Model of atom (positively charged nucleus, negatively charged electrons orbiting around the nucleus
 * 1917**-transmuted Nitrogen into Oxygen by bombarding Nitrogen with Alpha Rays. This was the first scientific and artificial instance of one element changing into another.
 * 1919**- Discovered protons
 * 1921**- Proposed that Neutrons could exist (but didn’t discover them)



Rutherford is most famous for his Gold Foil Experiment. He shot alpha rays at a flattened out sheet of gold and surrounded the sheet with Alpha-ray detecting paper. When he shot alpha rays at the gold foil, instead of going straight through like he thought they would, some of the particles were bounced back at him. This led Rutherford to believe that the atom had a small and dense nucleus, and gave form to the Rutherford Model of the atom. Rutherford also defined Alpha, Beta, and Gamma rays by their power of penetration. Beta Rays penetrated further than Alpha Rays, and Gamma Rays penetrated the most.

**Albert Einstein**


 * Born**: March 14, 1879
 * Died**: April 18, 1955
 * Country of Origin**: Kingdom of Württemberg (Modern-day Germany)
 * Year of Discovery**: **June 9th, 1905**- (“//On a Heuristic Viewpoint Concerning the Production and Transformation of Light”)// Photoelectric effect
 * 1921-Nobel Prize in Physics** (“for his services to theoretical physics, and especially for his discovery of the law of the photoelectric effect”)

In 1933 Einstein was in America giving lectures when Hitler came to power. Being Jewish, Einstein did not go back and instead lived the rest of his life in America.

Einstein is most known for his work about special relativity. on September 26th 1905, Einstein published his paper “On the Electrodynamics of Moving Bodies”. In the paper was his now famous equation dealing with the mass of objects at close to the speed of light, E=mc2 (Energy=mass x speed of light2)

Einstein wrote a letter to FDR in which he voiced his concern that the Nazis were attempting to create an atomic bomb. On Einstein’s recommendation, FDR authorized an atomic weapon program that came to be known as the Manhattan Project.

**Neils Bohr**
 * Born**: October 7, 1885
 * Died**: November 18, 1962
 * Country of Origin**: Denmark
 * Year of discovery**: **1913**-first publication of atomic structure, in which he concludes that electrons revolve around the nucleus in fixed orbits.
 * 1922**-Nobel Prize in Physics ("for his services in the investigation of the structure of atoms and of the radiation emanating from them.")

Neils Bohr proposed that the electrons that orbit the nucleus did so in fixed paths, this model was superior to Rutherford’s model because if Rutherford’s model was correct, then the atom would and should collapse. The fixed orbits in Bohr’s model ensured that this would not happen.

Bohr did most of his research in the years following WW1, and during WW2. He was Jewish, and fled Denmark in October of 1943, alongside the thousands of other Jews who were able to escape Denmark and go to Sweden. Bohr was actually responsible for this mass exodus, having persuaded the King of Sweden to let the Jews enter the country. From Sweden he was flown to England and then the US to work on the US Nuclear program, nicknamed the “Manhattan Project”

Bohr himself was against the use of atomic weapons, but worked at the Los Alamos Research Center as a consultant.

**1915-1950**

**Erwin Schrodinger**


 * Born:** August 12th, 1887
 * Died:** January 4th, 1961
 * Country of Origin:** Austria
 * Year of Discovery: 1933-** Nobel prize in physics from his work on Wave Mechanics
 * 1935**- Schrodinger's cat thought experiment



Erwin Schrodinger was a commissioned officer in the Austrian army’s artillery division in WW1. He opposed the Nazi’s persecution of Jews and in 1933 fled Germany after moving there earlier. This opposition got him in trouble with the Nazis when they annexed Austria, so he wrote a letter that recanted his statements. THIS act put him at odds with all of the other Universities he visited during WW2, and he later personally apologized to Albert Einstein, Einstein being Jewish. He went to Ireland and then to the UK to work at Oxford.

Schrodinger’s Cat is a thought experiment Schrodinger created in 1935, and is (to the commoner) what Schrodinger is most well-known for. In the experiment, a cat is placed in a box, alongside a radioactive object, a Geiger counter, and a vial of poison. If the Geiger counter detects the radioactive object, a hammer will smash the poison and the cat will die. The twist is that while the box is closed, the cat is either alive or dead, and at the same time alive AND dead.

**James Chadwick **


 * Born **: October 20, 1891
 * Died **: July 24th 1974
 * Country of Origin **: England
 * Year of Discovery **: **1932**: //Hughes Medal of the Royal Society//
 * 1935**: Nobel Prize in Physics
 * 1945**: Knighted

James Chadwick discovered the existence of neutrons. He realized that atoms could be split by neutrons as they are neutral and would not be affected by the positive charge of the protons, or the negative charge of the electrons. Another significance of this discovery was that it was now easier to understand the concept of isotopes, and thus atomic mass.

**Werner Heisenberg**


 * Born:** December 5, 1901
 * Died:** February 1, 1976
 * Country of Origin:** Germany
 * Year of Discovery:** **1927**-Heisenberg Uncertainty Principle
 * 1932**-Nobel Prize in Physics

Heisenberg was recruited to work for the German Nuclear Energy Project in 1939. He had been persecuted by the SS in 1933 for defending the discoveries of Jewish scientists, but in 1938 was resolved of any wrongdoing. During his work on atom he developed his Uncertainty Principle in 1927. The Uncertainty Principle states that the location of an electron at any given point in time cannot be certain, but that the electron WILL be found in the numerous electron orbitals that encompass an atom’s nucleus. In more scientific terms, the momentum and speed of the electron make it impossible to know where it will currently be, as it takes more than one measurement to determine where it once was. Heisenberg was captured in his house on May 3rd, 1945 by allied forces who were abducting German scientists behind enemy lines and sending them to England to gain intelligence of the German Nuclear project.

**ATOMIC MODELS THROUGHOUT TIME**

**__Solid Sphere Model__** John Dalton was the man who proposed that the atom was a solid sphere that bonded to other atoms (also spheres) in fixed ratios. Dalton’s Atomic theory had 4 major points. First, elements are made up of small particles called atoms. Second, the way elements can be told apart at the atomic level is through their atomic mass, which would be different to all the other elements. Third, atoms bond together in ratios to form compounds, and these ratios do not change. Fourth, atoms are not created or destroyed in chemical reactions. This model was more refined than Democritus’s model. Democritus proposed that all matter was made up of very small objects that represented the larger solid/liquid/gas. For example, a water atom would be a soupy blue sphere, while an iron atom would be hard, square, and spiky. What was inaccurate about Dalton’s model was that the same elements could have different atomic masses, through what is called isotopes. Also, through nuclear chemistry, we know that atoms can be destroyed and created through nuclear reactions.

**__Plum Pudding Model__** JJ Thomson proposed his atomic model after discovering the electron in 1897. In his model, he proposed that electrical energy could displace or “pluck” electrons out of the atom. It was the glowing of the crookes tube that gave him this idea. Using a magnet he determined that the electrons had a negative charge, and if the atom was losing negativity, it was becoming positive. Thus, Thomson’s model is a large positive atom, with smaller electrons imbedded into it. **__Planetary Model__** The Planetary model was proposed by Ernest Rutherford in 1911. In this model, the electrons orbit the nucleus of an atom in the same way planets in our solar system orbit the sun. In this manner, most of the mass of the atom is located in the nucleus, again analogous to our solar system where most of the mass is located in the sun. Rutherford’s reasoning came as a result of his Gold Foil experiment. In this experiment, he discovered that atoms had a dense center (nucleus), which alpha rays cannot go through. This meant that JJ Thomson’s Plum Pudding model was wrong. Rutherford had proven that the electrons were not imbedded in the nucleus. **__Bohr Model__** Bohr’s model attempted to explain the energy that was released by atoms in the form of light. The model is similar to Rutherford’s planetary model, but the electrons stay in fixed orbits, and need to be supplied with energy to ascend or descend the orbital shells. Bohr’s model worked with simple atoms, such as hydrogen, which was the element he worked with. However, it could not explain the atom when the nucleus becomes more complex (iron, arsenic, nuclei). **__Electron Cloud Model__** This model was proposed by Heisenburg, gave a clearer explanation of the behavior of electrons, and is currently the most accurate model of the atom. Heisenburg proposed the Heisenburg Uncertainty Principle in 1927. He determined that there was no way of knowing exactly where an electron was at any given point in time, only that they were organized in shells that surrounded an atom’s nucleus. In this way, the electrons are contained to shells such as in the Bohr Model, but they are not in fixed paths. The result is orbitals of electrons that look like “clouds”, or approximations of where an electron will be.

James Chadwick discovered the existence of neutrons. He realized that atoms could be split by neutrons as they are neutral and would not be affected by the positive charge of the protons, or the negative charge of the electrons. Another significance of this discovery was that it was now easier to understand the concept of isotopes, and thus atomic mass.