The History of the Atom

  • 384

    Aristotle's views on atoms.

    Aristotle's views on atoms.
    -Exact date unknown.
    -Aristotle was born in 384 BCE in Stagira, Greece.
    -Aristotle did not believe in atoms and thought that all matter was made of earth, air, fire, and water.
    -Aristotle was believed to be correct at the time, but Democritus was proved correct around 2,000 years later.
    -Aristotle died in Chalcis, Greece in 322 BCE.
  • 460

    Democritus's atomic theory

    Democritus's atomic theory
  • Antoine Lavoisier proposes the Law of Conservation of Mass

    Antoine Lavoisier proposes the Law of Conservation of Mass
    Antoine Lavoisier was born on August 26th, 1943 in Paris France. He was a nobleman who played an important role in discovering the Law of Conservation of Mass in 1789. Licensed to practice law, Lavoisier chose science instead. The man has become known as the "Father of Modern chemistry", and for good reason. He recognized and named hydrogen and oxygen, both of which having to do with his new theory of combustion, and even helped develop the metric system.
  • Lavoisier cont.

    Lavoisier cont.
    In 1789, Lavoisier discovered the Law of Conservation of Mass, which stated that mass of a substance before a chemical reaction will equal the mass of the same substance after a chemical reaction. Though this may seem obvious, this idea would revolutionize science. Lavoisier was later executed during the French Revolution on May 8th, 1794.
  • Joseph Proust discovers the law of Definite Proportions

    Joseph Proust discovers the law of Definite Proportions
  • Dalton's Atomic Theory & Spherical Model

    Dalton's Atomic Theory & Spherical Model
    John Dalton was born on September 6th, 1766 in Eaglesfield, England. Dalton became a school teacher at the age of 15, but would later go on to work in science. Working as a mathematics and natural philosophy professor at the “New College” in Manchester, after his teaching days, Dalton developed his atomic theory in 1808. Linking elements to atoms, the Law of Conservation of Mass, and the Law of Definite Proportions, he stated four main ideas for theories:
  • Dalton cont.

    Dalton cont.
  • Dalton cont. even more

    Dalton cont. even more
    Though this theory and model was partly incorrect, it was one of the first major steps in learning about the atom. Dalton also did extensive research in color-blindness and died on July 27th, 1844.
  • J.J. Thompson discovers the elctron and proposes the Plum Pudding Model

    J.J. Thompson discovers the elctron and proposes the Plum Pudding Model
    J.J. Thompson was born in Manchester, England on December 18th, 1856, learning at Owens College in Manchester and Trinity College in Cambridge. In 1897, he performed an experiment where he sent electricity through a cathode-ray tube and the gas glowed. When the small cathode ray particles bent toward the positive pole of the magnet, he realized these particles must have a negative charge. He called these particles “corpsucles”, which later came to be known as electrons.
  • Thompson cont.

    Thompson cont.
    Thompson proposed that all atoms included electrons, and that for the atoms to be neutral, they must also contain a positive charge to cancel out the negative charge. Thompson would later go on to propose the “plum pudding model” of the atom, where tiny negative electrons are embedded in a soft sphere with a positive charge. Thompson had proved atoms were made up of smaller particles that contained charges. Thompson died on August 30th, 1930.
  • Max Planck propes his Quantum Theory

    Max Planck propes his Quantum Theory
  • Robert Millikan discovers the charge of an electron using the "oil drop experiment."

    Robert Millikan discovers the charge of an electron using the "oil drop experiment."
  • Ernest Rutherford publishes Nuclear Model (Planetary Model) of atom

    Ernest Rutherford publishes Nuclear Model (Planetary Model) of atom
  • Rutherford cont.

    Rutherford cont.
    -Directed the gold foil experiment in 1909, where associates Hans Geiger and Ernest Marsden fired alpha particles at a thin sheet of gold foil. These particles are positively charged helium nuclei.
    - Rutherford believed that most of the particles would be slightly deflected. Instead, most passed right though, only a few were slightly deflected, and very few (1/8000) were greatly deflected.
    - Rutherford concluded that the atom is mostly empty space, and at the center of the atom was a nucleus.
  • Rutherford cont. even more

    Rutherford cont. even more
  • Rutherford cont. for the 4th time

    Rutherford cont. for the 4th time
  • Niels Bohr proposes Bohr's Model

    Niels Bohr proposes Bohr's Model
  • Bohr cont.

    Bohr cont.
  • Erwin Schrodinger proposes the Quantum Mechanical Model

    Erwin Schrodinger proposes the Quantum Mechanical Model
  • Schrödinger cont.

    Schrödinger cont.
  • Heisenberg proposes his Uncertainty Principle

    Heisenberg proposes his Uncertainty Principle
  • James Chadwick discovers the neutron and creates the modified nuclear atom model.

    James Chadwick discovers the neutron and creates the modified nuclear atom model.
    -Born on October 20th, 1891 in Bollire, England. He studied at the University of Manchester under Ernest Rutherford.
    -In 1932, he discovered the neutron. This discovery leads to the modified nuclear model, which is essentially the same as Rutherford’s original, but instead of a basic positively charged nucleus, the nucleus was made up of positive protons and neutral neutrons.-He was also head of all the British scientists in the Manhattan Project in World War II.
    -He died on July 24th, 1974.