-
460
Early Greek Models - Democritus
460 BC - 370 BC- influential pre-Socratic philosopher
- many consider him to be the 'father of modern science'
- atomist, they tried to explain the world without reasoning to purpose, or final cause.
- answered questions with a mechanistic explanation
- believed everything composed of 'atoms' which are physically but not geometrically indivisible
- the type of material including all of its characteristics corresponded to the shape of the atoms involved
- famous for his theories of the atom
-
Period: 460 to
Chemistry
-
Jan 1, 1500
Medieval Alchemy
16th century -mixture of science, philosophy and mysticism
- try to discover the relationship of man to cosmos
- they identified arsenic, antimony, and bismuth first
- produced hydrochloric acid, nitric acid, potash & sodium carbonate
- is a foundation for chemistry as a scientific discipline
- through their experiments, medieval alchemists invented and developed labratory devices and procedures that are, in modified form, used today -
John Dalton
September 6th 1766 - July 27th 1844- English chemist, meteorologist and physicist
- discovered a type of colour blindness (deuteroanopia)
- presented series of papers on the constitution of mixed gases, pressure of steam, evaporation and thermal expansion of gases
- theorized that elements are made up of tiny particles called atoms
- atoms of a given element are different from those of any other element
- all the atoms of a given element are identical
- most known for atomic theory
-
Henri Becquerel
December 15th 1852 - August 25th 1908- French physicist
- the dicovery of radioactivity along with Marie Curie and Pierre Curie is associated with him
- SI unit of radioactivity is (Bq) becquerel is named after him.
- while investigating phosphorescence in uranium salt he accidentally discovered radioactivity
- his radioactivity discovery led him to investigate the spontaneous emission of nuclear radiation
- he also worked on the subject of terrestrial magnetism
-
J.J. Thomson
December 18th 1856 - August 30th 1940- discovered the electron in a series of experiments designed to study the nature of electric discharge in a high-vaccuum cathode-ray tube
- credited for discovery of the elctron & isotopes, and invention of the mass spectrometer
- worked on conduction of electricity in gases
- revealed the nature of atoms and electromagnetic forces
- 1st to suggest fundamental unit of atom was 1000x smaller than an atom (sub-atomic particles - electrons)
-
Pierre Curie
May 15th 1859 - April 19th 1906- French physicist
- pioneer in crystallography, magnetism, piezoelectricity, radioactivity and Nobel laureate
- designed and perfected an extremely sensitive torsion balance for measuring magnetic coefficients
- discovered the effect of temperature on paramagnetism now known as Curie's Law
- him and one of his students made the first discovery of nuclear energy
-
Marie Curie
November 7th 1867 - July 4th 1934- Polish born French physicist and chemist
- Two Nobel prizes in physics and chemistry
- creation of the theory of radioactivity
- techniques for isolating radioactive isotopes
- discovery of two new elements, polodium and radium
- under her direction the worlds first studies were conducted into the treatment of neoplasms(cancers) using radioactive isotopes
-
Ernest Rutherford
- August 30th 1871 - October 19th 1937*
- New Zealand born British physicist and chemist
- coined the terms alpha and beta to describe the two distinct types of radiation emitted by thorium and uranium
- demonstrated that radioactivity was the spontaneous disintigration of atoms
- realised radium was much more powerful than the alpha and bata radiation rays so he named the more powerful radiation "gamma rays"
- first person to transmute one element into another one when he converted N into O
-
Niels Bohr
October 7th 1885 - November 18th 1962- nobel prize in physics
- described as most influential scientist of the 20th century
- the bohr model of the atom, the theory that electrons travel in discrete orbits around the atom's nucleus
- the shell model of the atom, where the chemical properties of an element are determined by the electrons in the outermost orbit
- the liquid drop model of the atomic nucleus
- indentified the isotope of uranium that was responsible for slow-neutron fission
-
James Chadwick
October 20th 1891 - July 24th 1974- worked on ionization of phosphorous and also on the photo-chemical reaction of carbon monoxide and chlorine
- 1932 discovered a previously unknown particle in the atomic nucleus (known as neutron because of its lack of electric charge)
- discovery was crucial for the fission of Uranium 235
- his discovery made it possible to create elements heavier than uranium in the lab
- led chemists to the revolutionary discovery of 'nuclear fission'
