Fall.2008.MMA.Zheng.Chenyang

=**Timeline**=

Democritus was born in the city of Abdera in Thrace, an lonian colony of Teos. Nature’s basic particle an atom, based on the Greek meaning “invisible”. His view was not supported by evidence so his ideas were not thought to be true. Later, Dalton turned Democritus’ ideas into a scientific theory.



**Heraclitus** (ca. 535–475 BC)
Heraclitus was born to an aristocratic family in Ephesus, present-day Efes, Turkey. Heraclitus's philosophy is perhaps even more fundamental in the formation of the European mind than any other thinker in European history, including Socrates, Plato, and Aristotle. He is best known for his doctrines that things are constantly changing (universal flux), that opposites coincide (unity of opposites), and that fire is the basic material of the world.



**Alchemists (about 1000-1650)**
Attempted to (1) change lead and other base metals to gold; (2) discover a universal solvent; and (3) discover a life-prolonging elixir. Used plant products and arsenic compounds to treat diseases.

= = =Aristotle ( 384-322 BCE) = Aristotle was born in 384 BCE. At Stagirus, a Greek colony and seaport on the coast of Thrace. Aristotle sees the universe as a scale lying between the two extremes: form without matter is on one end, and matter without form is on the other end. The passage of matter into form must be shown in its various stages in the world of nature.

= = =Theophrastus (371 – c. 287 BC)= in general to have emphasized the empiricist side of Aristotle's thought and downplayed remaining Platonist elements, a trend that was further continued by Theophrastus' successor as head of the Lyceum, Strato. Theophrastus criticized some of Aristotle's arguments for the existence of a Prime Mover, and he expressed dissatisfaction with Aristotle's universal application of teleological (that is, goal-directed) explanations.

= = = Robert Boyle (1627-1691) =

Formulated fundamental gas laws. First to conceive the possibility of small particles combining to form molecules; distinguished between compounds and mixtures; studied air and water pressures, desalination, crystals and electrical phenomena.

= = =Antoine Lavoisier **(1743-1794)**=

He is most noted for his discovery of the role oxygen plays in combustion. Lavoisier is now known as the Father of Modern Chemistry. Lavoisier was an excellent discoverer because he was quick to see the significance of new findings. He readily confirmed and extended the experimental discoveries of others and formed mental models to organize all of these ideas. He was one of the few chemists at the time to fully appreciate the importance of careful measurements of reactants and products. In order to make such careful measurements he invented a balance which was good to about .000 grams. He proved the Law of Conservation of Mass, showing that the mass of the reactants had to equal the mass of the products.

**Charles Coulomb (1736-1806)**
Coulomb was born in Angouleme, France. Coulomb discovered the law that states, it is the force involved in atomic reactions. The magnitude of the electrostatic force between two point electric charges is directly proportional to the product of the magnitudes of each charge and inversely proportional to the square of the distance between the charges.
 * Coulomb's law**



**John Dalton (1766-1844)**
John Dalton borne on September 6, 1766 in Cumberland, England. The first great chemical theorist; proposed atomic theory (1807); stated law of partial pressure of gases. His ideas led to laws of multiple proportions, constant composition and conservation of mass. Dalton's theory was presented in //New System of Chemical Philosophy// (1808-1827). This work identified chemical elements as a specific type of atom, therefore rejecting New tons theory of chemical affinities.



William Crookes (1**832-1919)**
William Crookes was born in London, the eldest son of Joseph Crookes, who was a tailor of north-country origin. English physicist who experimented with cathode ray tubes with Goldstein. In 1903, he found that bright scintillations occurred in ZnS when a radioactive substance was nearby. This offered the first means of detecting alpha particles, and was used by Rutherford in his scattering experiment.

**W.K. Roentgen (1845-1923)**
Discovered x-radiation (1895). Awarded Nobel Prize in 1901. Wilhelm Roentgen's attention was drawn to a glowing fluorescent screen on a nearby table. Roentgen immediately determined that the fluorescence was caused by invisible rays originating from the partially evacuated glass Hittorf-Crookes tube he was using to study cathode rays (i.e., electrons). Surprisingly, these mysterious rays penetrated the opaque black paper wrapped around the tube. Roentgen had discovered X rays, a momentous event that instantly revolutionized the field of physics and medicine.



Henri Becquerel (**1852-1908****)**
Becquerel was born in Paris. Discovered radioactivity, deflection of electrons by magnetic fields and gamma radiation. Nobel Prize 1903 (with the Curies). In 1908, the year of his death, Becquerel was elected Permanent Secretary of the Académie des Sciences. Ekin = q • U = 1e • 1V = 1,6 • 10-19J



=**Marie Curie (1867-1934)**=

Marie Sklodowska was born in Warsaw. //Marie Curie was a Polish-born physicist and chemist and one of the most famous scientists of her time.// The Curie's research was crucial in the development of x-rays in surgery. During World War One Curie helped to equip ambulances with x-ray equipment, which she herself drove to the front lines. The International Red Cross made her head of its radiological service and she held training courses for medical orderlies and doctors in the new techniques. =**J.J. Thomson (1856-1940)**=

Joseph J. Thomson was born in 1856 in Cheetham Hill, Manchester in England, of Scottish parentage. In 1897 in Cambridge, J J Thomson experimented on cathode rays. In Britain, physicists had argued these rays were particles, but German physicists disagreed, thinking they were a type of electromagnetic radiation. Thomson showed that cathode rays were particles with a negative electric charge and much smaller than an atom. He also thought all atoms contained them. These particles were later named electrons.

=**Robert Millikan (1868-1953)**=

He was born on the 22nd of March, 1868, in Morrison, Ill. (U.S.A.) He chiefly in the fields of electricity, optics, and molecular physics. His earliest major success was the accurate determination of the charge carried by an electron, using the elegant "falling-drop method"; he also proved that this quantity was a constant for all electrons (1910), thus demonstrating the atomic structure of electricity.

= = =**Ernest Rutherford (1871-1937)**= Ernest Rutherford was born on August 30, 1871, in Nelson, New Zealand, the fourth child and second son in a family of seven sons and five daughters. Rutherford was the first to establish the theory of the nuclear atom and to carry out a transmutation reaction (1919) (formation of hydrogen and and oxygen isotope by bombardment of nitrogen with alpha particles). Uranium emanations were shown to consist of three types of rays, alpha (helium nuclei) of low penetrating power, beta (electrons), and gamma, of exceedingly short wavelength and great energy. = =



Neils Bohr(1885-1962)
Niels Henrik David Bohr was a Danish physicist who made fundamental contributions to understanding atomic structure and quantum mechanics, for which

he received the Nobel Prize in Physics in 1922.



=**Erwin Schrodinger- (1887-1961)** = Erwin Schrodinger was born on August 12, 1887, in Vienna. His dissatisfaction with the quantum condition in Bohr's orbit theory and his belief that atomic spectra should really be determined by some kind of eigenvalue problem. For this work he shared with Dirac the Nobel Prize for 1933.



= = =**James Chadwick (1891-1974)**=

James Chadwick was born in Bollington, Cheshaire. Discovered the neutron (1932) Nobel Prize 1935. In 1932 Chadwick made a fundamental discovery in the domain of nuclear science : he discovered the particle in the nucleus of an atom that became known as the neutron because it has no electric charge.