• 348


    384-322 b.c.
    He rejected teh atomic theory entirely because it did not agree with his own ideas on nature.
  • 460


    Democritus was a Greek philosopher (460-370 b.c.) was the first person to propose the idea that matter was infinitely divisible. He believed matter was made up of tiny individual particles call atoms.
  • Antonie Lavosier

    Antonie Lavosier
    In the 1790s he complied a list of elements known at teh time. The list contained 23 elements. Many of these elements such as silver, gold, carbon, and oxygen.were known since prehistoric times.
  • Joesph Proust

    Joesph Proust
    He first published his Law of Definite Proportions in 1794. This law states that a compound of exact proportions of elements by mass regardless of how the coupound was created.
  • John Dalton

    John Dalton
    He proposed his atomic theory based on research he had done and by going off of Democritus theory,
  • Louisiana Purchase

    Louisiana Purchase
    Thomas Jefferson doubled the United States of America's area. The U.S. paid 60 million francs for this deal and the area compriises some 15 states.
  • Amadeo Avagadro

    Amadeo Avagadro
    In 1811 Avogadro hypothesized that equal voulmes of gases at the same temperature and pressure contain equal numbers of molecules.
  • The American Revolution

    The American Revolution
    The American Revolution was actually the political upheaval during the last half of the 18th century. There are thirteen colonies in North American that joined together to break free from British Empire.
  • William Crookes

    William Crookes
    He accidently invented a cathrode ray. While noticing a flash of light in one of his tubes. The flash was produced by some form of radiation striking a light-producing coating that had been applied to the end of the tube.
  • American Civil War

    American Civil War
    This war in the United States happened in order to fought over the secession of the Confederate States There are eleven southern states that declared their secession from United States and formed the Confederate States do America. The Confederacy surrendered and slavery was abolished right after the four year war.
  • Assassination of Abraham Lincoln

    Assassination of Abraham Lincoln
    Lincoln was shot in the back of the head with a .44 caliber Derringer, percussion-cap pistol, during a performance of "Our American Cousin," at Ford's Theater in Washington D.C.
  • J.J. Thomson

    J.J. Thomson
    He began series of catode ray tube experiements to determine thae ratio of its charge to its mass. By measuring the effect of both magnetic and electric fields of a cathrode ray he was able to determine the charge to mass ratio. Comparing it to other know ratios he realized that it was less than the lightest known atom, hydrogen.
  • Henri Becquerel

    Henri Becquerel
    While studying the effect of x-rays on photographic film, he discovered some chemicals spontaneously decompose and give off very pentrating rays.
  • Madame Curie

    Madame Curie
    Studied uranium and thorium and called their spontaneous decay process radioactivity. She and her husband Pierre also discovered the radioactive elements polonium and radium.
  • Max Planck

    Max Planck
    Began searching for an explanation as he studied the light emitted from heated objects. His study of the phenomenon led him to a startling conclusion that matter can gain or lose energy only in small specific amounts called quanta.
  • Albert Einstein

    Albert Einstein
    In 1905 he proposed that electromagnetic radiation has both wavelike and particlelike natures. That is, while a beam of light has many wavelike characteristics, it also can be thought of as a stream of tiny particles called photons. He also published the famous equations E=mc squared.
  • Robert Milikan

    Robert Milikan
    He determined the charge of an electron. His experimental setup and technique that the charge he used to measure with almost 100 years ago is within 1% of the accepted value today.
  • Henry Moseley

    Henry Moseley
    Discovered that atoms of each element contain a unique positive charge in their nuclei. The number of protons in an atom identifies it as an atom of a particular element. The number of protons in an atomis referred to as teh elements atomic number
  • Niels Bohr

    Niels Bohr
    Proposed a quantum model for the hydrogen atom that proposed that the hydrogen atom has only certain allowable energy states. The lovest allowable state of an atom is called its ground state.
  • Ernest Rutherford

    Ernest Rutherford
    Eight years after his revolutionary gold foil experiment, Rutherford had refinded the concept of the nucleus. He concluded that the nucleus contained positively charge particles called protons.
  • Louis de Broglie

    Louis de Broglie
    Proposed an idea that eventually accounted for the fixed energy leves of Bohr's model. Used the de Broglie equation that help predict all moving particles have wave characteristics.
  • Erwin Schrodinger

    Furthered the wave particle theory proposed by de Brogile. He derived an equation taht treated the hydrogen atom's electron as a wave.
  • Werner Heisenberg

    Werner Heisenberg
    Proved to have profound implications for atomic models. Concluded that is is impossible to make any measurement on an object without distubing the object. The Heisenber uncertainty principle state that it is fundamentally impossible to know precisely both the velocity and position of a particle at the same time.
  • James Chadwick

    James Chadwick
    Showed that the nucleus also contained another subatomic particle, a neutral particle called the neutron. A neutron has a mass nearly equal to that of a proton, but it carries no electrical charge.
  • Manhattan Project

    Manhattan Project
    Was a research and development program by the United States with the United Kingdom and Canada that produced the first atomic bomb during World War II.
  • Vietnam War

    Vietnam War
    The U.S. government viewed involvement in the war in order to prevent a communist takeover of South Vietman. U.S. government involvment escalated in the early 1960s.
  • Assassination of John F. Kennedy

    Assassination of John F. Kennedy
    He was assassinated in Dealey Plasa, Dallas, Texas. He was seriously shot while traveling with his wife and teh latter's wife in a Presidential motorcade.
  • Apollo 11

    Apollo 11
    Apollo 11 was a spaceflight that brought the first human on the Moon and they are all Americans. Apollo 11 ended the Space Race and fulfilled a national goal proposed by President John F. Kennedy.
  • Twin Towers

    Twin Towers
    THere were series of four attacks upon the United States in New York City and the Washington D.C. areasons. Two planes crashed into the twin towers.
  • Death of Osama bin Laden

    Death of Osama bin Laden
    Osama bin Laden was killed in Pakistan by Navy SEALs of the United States Naval Special Warfare development Group.