-
460 BCE
Democritus born
Abdera, Greece -
400 BCE
Democritus contributions
What they contributed:
Promulgated the atomic theory, which asserted that the universe is composed of two elements: the atoms and the void in which they exist and move
Democritus did not originate the atomic theory; he learned it from its founder, Leucippus, the author of the Big Cosmology.
What experiments:
Separated a seashell into its smallest components -
370 BCE
Democritus death
-
Antoine Lavoisier born
Paris, France -
John Dalton born
Eaglesfield, England -
Antoine Lavoisier contributions
What they contributed:
Defined law of conservation of mass
This helped shape atomic theory b/c matter is composed of atoms that aren’t created or destroyed during chemical reactions
What experiments:
Heat and combustion of substances, reacted oxygen with inflammable air -
Antoine Lavoisier death
Paris, France -
John Dalton contributions
What they contributed:
All matter is made up of indivisible and indestructible atoms w distinct properties
What experiments:
Combined oxygen with two volumes of nitric oxide over water -
John Dalton death
Manchester, UK -
J.J. Thomson born
Cheetham Hill, UK -
Max Planck born
Kiel, Germany -
Marie Curie born
Warsaw, Poland -
Robert Millikan born
Morrison, Illinois, U.S. -
Ernest Rutherford born
Nelson, New Zealand -
Albert Einstein born
Uhm, Germany -
Niels Bohr born
Copenhagen, Denmark -
Erwin Schrödinger born
Vienna, Austria -
James Chadwick born
Manchester, UK -
Louis De Broglie born
Dieppe, France -
J.J. Thomson
What they contributed:
All atoms contain negatively charged subatomic particles or electrons
Plum pudding model
What experiments:
Cathode rays were negatively charged -
Max Planck contribution
What they contributed:
Quantum theory
What experiments:
Studied the diffusion of hydrogen through heated platinum -
Werner Heisenberg born
Wurzburg, Germany -
Marie Curie contribution
What they contributed:
Discovered polonium and radium
What experiments:
Studied mineral pitchblende -
Robert Millikan contribution
What they contributed:
Accurate determination of the charge carried by an electron
What experiments:
Falling-drop method -
Albert Einstein contribution
What they contributed:
Helped revolutionize the sciences with statistics and probability
What experiments:
Mathematically proved the existence of atoms -
Ernest Rutherford contribution
What they contributed:
Mass of the atom is concentrated in its nucleus
What experiments:
Gold foil experiment -
Niels Bohr contribution
What they contributed:
Proposed a theory for hydrogen atom based on quantum theory
What experiments:
Bohr model -
Louis De Broglie contribution
What they contributed:
Particles, such as electrons, could be described not only as particles but also as waves
What experiments:
Streams of electrons were reflected against crystals -
Werner Heisenberg contribution
What they contributed:
Discovered the uncertainty principle
What experiments:
Formulated quantum mechanics in terms of matrices -
Erwin Schrödinger contribution
What they contributed:
Wave equation that calculates the energy level of electrons in atoms
What experiments:
Bohr’s orbit theory -
James Chadwick contribution
What they contributed:
Proved the existence of neutrons
What experiments:
Measured mass and performed an experiment that others were tinkering with -
Marie Curie death
France -
Ernest Rutherford death
Cambridge, UK -
J.J. Thomson death
Cambridge, UK -
Max Planck death
Göttingen, Germany -
Robert Millikan death
Pasadena, California, U.S. -
Albert Einstein death
Princeton, New Jersey, U.S. -
Erwin Schrödinger death
Vienna, Austria -
Niels Bohr death
Copenhagen, Denmark -
James Chadwick death
Cambridge, UK -
Werner Heisenberg death
Munich, Germany -
Louis De Broglie death
Paris, France