Fall.2008.MMA.Hart.Timeline

Atomic History Timeline

toc =Ancient Times=

> > **Lifespan:** circa 460 BC - 370 BC > **Country of Origin:** Greece > **Year of Discovery:** -456 > **Biography:** Democritus was a materialist philosopher born at Abdera in Thrace. He was a student of Leucippus, and it is very difficult to tell which of his work is his own or a reflection of Leucippus' ideas. His name in Greek means "chosen of the people." Democritus spent the inheritance his father left him to travel to other lands in search of knowledge and experience. > **Discovery:** Democritus was the first to conceive matter in the form of particles, which he called "atoma", the derivative of today's "atom."
 * > ==Democritus==

> "By convention there is sweet, by convention there is bitterness, by convention hot and cold, by convention color; but in reality there are only atoms and the void." -Democritus, on his belief that everything can be broken down to nothing more than atoms.

> **Sources:** > http://www.chemistry.co.nz/chronology.htm > http://en.wikipedia.org/wiki/Democritus ||

> > **Lifespan:** 384-322 BC > **Country of Origin:** Greece > **Year of Discovery:** Unknown > **Biography:** Democritus was a materialist philosopher born at Abdera in Thrace. He was a student of Leucippus, and it is very difficult to tell which of his work is his own or a reflection of Leucippus' ideas. His name in Greek means "chosen of the people." Democritus spent the inheritance his father left him to travel to other lands in search of knowledge and experience. > **Discovery:** Suggested that there is a 'void' between atoms, which today we call a 'vacuum'. He did this by referencing the work of Leucippus: "Unless there is a void with a separate being of its own, 'what is' cannot be moved-nor again can it be 'many', since there is nothing to keep things apart."
 * > ==Aristotle==

> **Sources:** > http://dbhs.wvusd.k12.ca.us/webdocs/AtomicStructure/Greeks.html > http://en.wikipedia.org/wiki/Aristotle ||

=1700-1800=

> > **Lifespan:** 1642-1727 > **Country of Origin:** England > **Year of Discovery:** 1704 > **Biography:** Isaac Newton was a genius in many aspects; he was a physicist, mathematician, astronomer, natural philosopher, alchemist and theologian. Most renowned for discovering the equation regarding universal gravitation, he is also instrumental in atomic history. > **Discovery:** Newton proposed a mechanical universe with small solid masses in motion. This was a huge development from earlier theories regarding the structure of matter.
 * > ==Sir Isaac Newton==

> **Sources:** > http://en.wikipedia.org/wiki/Isaac_newton > http://atomictimeline.net/index.php ||

> > **Lifespan:** 1743-1794 > **Country of Origin:** France > **Year of Discovery:** 1789 > **Biography:** Born to a rich family in Paris, and inherited a large fortune at the age of 5 with the death of his mother. Attended College Mazarin from 1754-1761, studying an array of subjects. > **Discovery:** At the time of his research, air and water were considered elements. Yet he determined that water was composed of hydrogen and oxygen, and that air is made up of a mixture of gases, primarily nitrogen and oxygen. In his "Traité Élémentaire de Chimie" (1789), he further explained and clarified the concept that an atom cannot be further broken down by an means of chemical analyses. It also presented his theories on the formation of compounds and elements.
 * > ==Antoine Lavoisier==

> **Sources:** > http://en.wikipedia.org/wiki/Antoine_Lavoisier ||

=1800-1875=

> > > **Lifespan:** 1766-1844 > **Country of Origin:** England > **Year of Discovery:** 1803 > **Biography:** Born into a Quaker family near Cumbria, England. He was an English chemist, meteorologist, and physicist. He was known as the "Father of Modern Chemistry." One of his notable students was James Prescott Joule, who discovered and named the SI derived unit of energy, the joule, after himself. > **Discovery:** Proposed an " atomic theory" with spherical solid atoms based upon measurable properties of mass. Basically, that an atom of an element is identical in every way to any atom of that same element.
 * > ==John Dalton==

> **Dalton's Atomic Theory** > **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.

> **Sources:** > http://atomictimeline.net/index.php > http://www.chemistry.co.nz/chronology.htm > http://en.wikipedia.org/wiki/John_Dalton > http://www.iun.edu/~cpanhd/C101webnotes/composition/dalton.html ||

> > **Lifespan:** 1834-1907 > **Country of Origin:** Russia > **Year of Discovery:** 1869 > **Biography:** Russian chemist and inventor. Born in Siberia. His grandfather was a Russian priest. He was the youngest among 17 siblings, but that number varies based on the source. At the age of 13, following the passing of his father and the burning down of his mother's factory, he went to school at the Gymnasium in Tobolsk. > **Discovery:** Arranged elements into 7 groups with similar properties. He discovered that the properties of elements "were periodic functions of the their atomic weights". This became known as the Periodic Law. Basically, the characteristics of elements would repeat every X number of elements, thus creating the groups we use today (he did not envision the noble gas group, and was reluctant to accept it, but eventually did so.)
 * > ==Dmitri Mendeleev==

> **Sources:** > http://atomictimeline.net/index.php > http://en.wikipedia.org/wiki/Dmitri_Mendeleev ||

> > **Lifespan:** 1826-1911 > **Country of Origin:** Ireland > **Year of Discovery:** 1874; 1891 > **Biography:** Born in the Irish midlands to an Anglo-Irish family, he attended Trinity College in Dublin and graduated with a B.A. in 1848 and a M.A. in 1852. Died at his home in Notting Hill, London in 1911. (An interesting tidbit about him: craters on the moon and Mars are named in his honor.) > **Discovery:** Proposed that electricity was made of discrete negative particles he called "electrons". He described electrons as the "fundamental unit quantity of electricity." The concept was proposed in 1874; it was not until 1891 that he coined the term itself.
 * > ==G.J. Stoney==

> **Sources:** > http://atomictimeline.net/index.php > http://en.wikipedia.org/wiki/G.J._Stoney ||

=1875-1900=

> > **Lifespan:** 1845-1923 > **Country of Origin:** Born in Prussia; German heritage > **Year of Discovery:** 1895 > **Biography:** Born at Lennep in Rhenish Prussia. He was an only child to a merchant and a cloth manufacturer. In 1869, he received a Ph.D. from the University of Zurich. While at Munich University, in 1901, Roentgen won the 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." > **Discovery:** Began his study of cathode rays in 1874. On November 8, 1895, he "produced and detected electromagnetic radiation in a wavelength range today known as x-rays or Roentgen rays."
 * > ==Wilhelm Conrad Roentgen==

> **Sources:** > http://www.blupete.com/Literature/Biographies/Science/Scients.htm > http://www.chemistry.co.nz/chronology.htm > http://en.wikipedia.org/wiki/Wilhelm_Conrad_R%C3%B6ntgen ||

> > **Lifespan:** 1852-1908 > **Country of Origin:** France > **Year of Discovery:** 1896 > **Biography:** Born in Paris, in a family that had four generations of scientists. He became learned in the field of science at the École Polytechnique and studied engineering at the École des Ponts et Chaussées. Married Louise Désirée Lorieux in 1890. > **Discovery:** While studying the effect of x-rays on photographic film, he discovered some chemicals spontaneously decompose and give off very penetrating rays.
 * > ==Henri Becquerel==

> The following is how he described the procedure for attaining the results he had discovered.

> "One wraps a Lumière photographic plate with a bromide emulsion in two sheets of very thick black paper, such that the plate does not become clouded upon being exposed to the sun for a day. One places on the sheet of paper, on the outside, a slab of the phosphorescent substance, and one exposes the whole to the sun for several hours. When one then develops the photographic plate, one recognizes that the silhouette of the phosphorescent substance appears in black on the negative. If one places between the phosphorescent substance and the paper a piece of money or a metal screen pierced with a cut-out design, one sees the image of these objects appear on the negative. … One must conclude from these experiments that the phosphorescent substance in question emits rays which pass through the opaque paper and reduces silver salts."

>

> **Sources:** > http://atomictimeline.net/index.php > http://en.wikipedia.org/wiki/Henri_Becquerel ||

> > **Lifespan:** 1856-1940 > **Country of Origin:** England > **Year of Discovery:** 1897 > **Biography:** Born in Cheetham Hill, Manchester, England, JJ Thomson went on to Study engineering and mathematics at Owens College and Trinity College. Among his students were Ernest Rutherford., who would eventual succeed him in his teaching position (Cavendish Professor of Physics). Earned a Nobel Prize in 1906. > **Discovery:** Used a CRT to experimentally determine the charge to mass ratio (e/m) of an electron =1.759 x 10 8 coulombs/gram. Also studied "canal rays" and found they were associated with the proton H +.
 * > ==JJ Thomson==

> **Sources:** > http://atomictimeline.net/index.php > http://en.wikipedia.org/wiki/J._J._Thomson ||

> > **Lifespan:** 1867-1934 > **Country of Origin:** Polish (Yet French Citizenship, and born in Warsaw when it was part of the Russian Empire) > **Year of Discovery:** 1898 > **Biography:** Born in Russia in 1867. Henri Becquerel was her Doctoral Advisor. The Curies, in 1903, won the Nobel Prize in Physics "in recognition of the extraordinary services they have rendered by their joint researches on the radiation phenomena discovered by Professor Henri Becquerel." > **Discovery:** Studied uranium and thorium and called their spontaneous decay process "radioactivity". She and her husband Pierre also discovered the radioactive elements polonium and radium. Named polonium after her Polish heritage.
 * > ==Marie Sklodowska Curie==

> **Sources:** > http://www.blupete.com/Literature/Biographies/Science/Scients.htm > http://atomictimeline.net/index.php > http://en.wikipedia.org/wiki/Marie_Curie ||

=1900-1915= > > **Lifespan:** 1868-1953 > **Country of Origin:** United States > **Year of Discovery:** 1909 > **Biography:** Grew up in smalltown Iowa. Received a Bachelor's degree in the classic from Oberlin college in Oberlin, Ohio, in 1891. His doctorate in physics is from Columbia University, which he earned in 1895 -- the first person to earn a Ph.D from the physics department at Columbia. Served as President of the California Institute of Technology from 1921 to 1945. Grew up in > **Discovery:** Oil drop experiment determined the charge (e=1.602 x 10 -19 coulomb) and the mass (m = 9.11 x 10 -28 gram) of an electron. Below is a depiction of the experiment apparatus.
 * > ==Robert Millikan==

>

> **Sources:** > http://atomictimeline.net/index.php > http://en.wikipedia.org/wiki/Robert_Millikan ||

> > **Lifespan:** 1871-1937 > **Country of Origin:** New Zealand > **Year of Discovery:** 1898; 1911 > **Biography:** Rutherford was the greatest of the pioneers of subatomic physics; he "led us to the confines of knowledge in respect of the ultimate structure and constitution of matter." > **Discovery:** Studied radiations emitted from uranium and thorium and named them alpha and beta. > Using alpha particles as atomic bullets, probed the atoms in a piece of thin (0.00006 cm) gold foil. He established that the nucleus was: very dense,very small and positively charged. He also assumed that the electrons were located outside the nucleus.
 * > ==Rutherford, Ernest==

> **Sources:** > http://www.blupete.com/Literature/Biographies/Science/Scients.htm > http://atomictimeline.net/index.php > http://en.wikipedia.org/wiki/Ernest_Rutherford ||

=1915-1950= > > **Lifespan:** 1885-1962 > **Country of Origin:** Denmark > **Year of Discovery:** 1922 > **Biography:** While at Copenhagen University, Bohr, in 1922, won the Nobel Prize in Physics "for his services in the investigation of the structure of atoms and of the radiation emanating from them." > **Discovery:** Developed an explanation of atomic structure that underlies regularities of the periodic table of elements. His atomic model had atoms built up of sucessive orbital shells of electrons. (As shown below in the Rutherford-Bohr model.)
 * > ==Niels Henrik David Bohr==

> **Rutherford-Bohr Model:** >

> **Sources:** > http://www.blupete.com/Literature/Biographies/Science/Scients.htm > http://atomictimeline.net/index.php ||

> > **Lifespan:** 1901-1976 > **Country of Origin:** Germany > **Year of Discovery:** 1927 > **Biography:** Born in Würzburg, Germany. Won the Nobel Prize in 1932. Played a major role in Nazi Germany, doing government nuclear research. As a result, he was arrested following World War II along with 9 other German scientists and detained from 1945-1946. > **Discovery:** Described atoms by means of formula connected to the frequencies of spectral lines. He proposed the Principle of Indeterminancy, also known as the Uncertainty Principle: you can not know both the position and velocity of a particle. Heisenburg also did research in quantum mechanics resulting in development of the orbital theory of chemical bonding.
 * > ==Werner Heisenberg==

> **Sources:** > http://atomictimeline.net/index.php > http://www.chemistry.co.nz/chronology.htm > http://en.wikipedia.org/wiki/Werner_Heisenberg ||

> > **Lifespan:** 1887-1961 > **Country of Origin:** Austria > **Year of Discovery:** 1930 > **Biography:** Born in Vienna, Austria. Attended the Akademisches Gymnasium in 1898. (A gymnasium is a term for a school.) Studied under Franz Serafin Exner frm 1906-1910, and ended up becoming an assistant to Exner in 1911. > **Discovery:** Viewed electrons as continuous clouds and introduced "wave mechanics" as a mathematical model of the atom.
 * > ==Erwin Schrödinger==

> **Sources:** > http://atomictimeline.net/index.php > http://en.wikipedia.org/wiki/Erwin_Schr%C3%B6dinger  ||

> > **Lifespan:** 1891-1974 > **Country of Origin:** England > **Year of Discovery:** 1932 > **Biography:** Born in Bollington, Chesire, England, he went to Bollington Cross C of E Primary School, followed by Manchester High School. LAter studied at the University of Manchester and the University of Cambridge. He would eventually work with Ernest Rutherford. For a period of time he was interned at the Ruhleben P.O.W. Camp, just outside of Berlin, Germany. During his internment he was allowed to set up a lab in the stables. Spent most of the years during the war at Ruhleben. Won a Nobel Prize in 1935. > **Discovery:** Using alpha particles, Chadwick discovered a neutral atomic particle with a mass close to a proton. Thus, he discovered the neutron.
 * > ==James Chadwick==

> **Sources:** > http://atomictimeline.net/index.php > http://en.wikipedia.org/wiki/James_Chadwick ||

> Discovered and theorized by ancient greek thinkers. The most basic of all theories. > ||
 * > **Invisible Solid Sphere Model**

> Created by Bohr and to be later changed and updated by Rutherford. Some people still follow this model today. Basically, it is a nucleus with a sphere around it where electrons are likely to be found. > ||
 * > **Electron Cloud Model**

> Most commonly used today. Most complex and detailed of all the models. Shows the orbit of the electrons around the nucleus, which is composed of the neutrons and protons. > ||
 * > **Planetary System Model**

> JJ Thomson created this model by imagining atoms made of small particles, called 'corpuscles' (which he thought composed cathode rayes), in a ball or group of packed positive charges. > ||
 * > **Plum Pudding Model**

> http://members.tripod.com/craigjm/physics2.html ||
 * > **Sources:**