History of Atomic Theory

By gabriellamfrager
  • 400 BCE

    Democritus

    a Greek philosopher, was the first person to propose the existence of atoms and the correlation between the structure and physical properties.
  • 400 BCE

    Leucippus

    Democritus studied under Leucippus, Leucippus was involved in the development of the atomic theory and had a big impact on these syuddies.
  • 400 BCE

    Aristotle

    Did not believe everything was made up of atoms like Democritus, he believed the universe was made up of fire water earth and air.

  • Antoine Lavoisier

    French revolution era: Law of conservation of mass, mass can not be created or destroyed during a chemical reaction. Executed in french revolution.

  • Joseph Proust

    Law of definite proportion, the proportion by mass of the element in a given compound is the same

  • John Dalton

    1. All matter is made of atoms, 2. Atoms of the same element are identical (wrong), 3. Atoms of different elements are different, 4. Atoms chemically combine in small whole number ratios to form compounds, 5. Atoms are indivisible(wrong), law of multiple proportions masses of one element combined w a fixed mass of another element will form simple or small whole number ratios

  • J. J. Thomson

    J. J. Thomson, a British physicist, discovered the electron. He discovered it by measuring the heat generated from cathode rays, beams of previously unknown electrons emitted from the cathode of a high-vacuum tube.

  • Max Planck

    Max Planck, a German physicist, is famous for Planck's constant (6.626 × 10-34 m2 kg / s) and Planck's postulate in general. Planck studied radiation around the time he discovered the Planck postulate (1900), which stated that electromagnetic energy could be emitted only in quantized form.

  • Robert Millikan

    Robert Millikan, an American physicist, is the man behind various studies of the photoelectric effect as well as the famous oil-drop experiment of his own design. Millikan is best known for his studies of electronic charge.

  • Ernest Rutherford

    Ernest Rutherford, a British physicist, created the Rutherford atomic model. Rutherford developed the Rutherford atomic model. This model was designed following numerous experiments conducted with gold-foil.

  • Niels Bohr

    Niels Bohr, a Danish physicist, proposed the Bohr model. Bohr expanded upon Rutherford's nuclear structure and created a atom model (called the bohr model).

  • Louis de Broglie

    Louis de Broglie, a French physicist, was known for his studies regarding quantum theory. De Broglie is responsible for predicting wave nature of electrons and such. He developed and announced his theory of electron waves.

  • Werner Heisenberg

    German physicist and philosopher, discovered a way to formulate quantum mechanics in terms of matrices. the position and the velocity of an object cannot both be measured exactly at the same time.

  • Erwin Schrödinger

    Austrian physicist, proposed wave mechanics.
    Schrödinger developed his own quantum mechanical model of the atom. This model was one of the first to display the orbitals on an atom.