Contributions to the Atomic Theory

Events

Democritus

460 BCE - 360 BCE

Argued that the world, including human beings are composed of very small particles which are called "atoms". These atoms are make up everything we see and are. He is most famous for being the first person to purpose that atoms exists and was made up of matter. He traveled all around central Europe, Asia, and Africa studying and developing his atomic theory. Used analogies of experiments and gave a picture of the atoms and distinguished them by size, shape, and arrangement of their parts.

Antoine Lavoisier

1743 - 1794

Most popular for his discovery of the role Oxygen plays in combustion's in 1778. He also named Oxygen and Hydrogen in 1788. Wrote the first extensive list of elements, helped to reform chemical nomenclature. He also predicted the extensive of silicon in 1787 and also the first to established that sulfur was an element rather than a compound . Discovered that although matter may change its form of shape the mass always stays the same. He is known for his experimental skills. One of his favorite experiments is turning Hg O into Hg + O. He used experiments to help come up with the law of conservation. The law states that matter rearrangement of matter in reactions. Interesting Fact: He was suspected of treason during the French Revolution.

J.J. Thompson

1856 - 1940

Discovered the electron by experimenting with a Crookes (or cathode ray tube). Demonstrated that cathode rays were negative charged. Later discovered a method used to separate different kinds of atoms and molecules from the use of positive rays. He discovered electrons and that an atom can be divided. Atoms are made up of positive cords and negative charged particles within it. Known for "Plum Pudding Model" before the atomic nucleus was discovered. Theorized the electromagnetic mass of a charged particle and demonstrated that speed increased the mass of a charged particle. Interesting Facts: June 12th, 1884 he was elected Fellow of the Royal Society on December 22 of that year became Cavendish Professor of Physics at the University of Cambridge. In 1918 he became Master at the Trinity College and held the position till death

Max Planck

1858 - 1947

Discovered that hot objects do not radiate a smooth, continuous range of energies as had been assumed in classical physics. Instead found out that the energies radiated by hot objects have distinct values with all other values forbidden. Used Plancks quantum. 1st wife died of illness, both daughters died at childbirth, eldest son died in WWl and in 1944, second son was executed but the Nazis for involvement in a plot to assassinate Hitler.

Marie Curie

1867 - 1934

Discovered thorium emitted radiation and that the amount of radiation depended upon the amount of element present in the compound. She found that radioactivity does not depend on how atoms are arranged into molecules, but rather that it originates within the atoms themselves. Both Curies discovered two new elements; radium and polonium. Durning WWl she served as the director of the Red Cross radiology service

Robert Millian

March 22, 1868 - December 19, 1953

Measured the charge on an electron with the apparatus. Verified Albert Einsteins photoelectric equation and developed the first photoelectric calculation of Plancks constant h. In his sophomore year of college was asked to teach an introductory. Received PhD in 1895.

Ernest Rutherford

1871 - 1937

Proposed an Atomic Model in 1911 also called nuclear atom or planetary model of an atom. Model described the atom as a tiny, dense, positively charged core called a nucleus, in which nearly all the mass is concentrated, around the light of electrons. Kind of around how planets revolve around the sun. performed an experiment to test the plum pudding model. Also known for the Gold Foil Experiment. Published his atomic theory describing the atom as having a central positive nucleus surrounded by negative orbiting electrons. Interesting Facts: Brothers drowned in 1886. Was denied permission to teach each time he applied for a job. Element "Rutherford" is in his honor. Born with an umbilical hernia which was left untreated causing him to die. On his birth certificate his name was misspelled so technically his real name was "Earnest Rutherford".

Albert Einstein

March 14, 1879 - April 18, 1955

Became famous for the Theory of Relativity, which laid the basis for the release of atomic energy. Accurately calculated both the diameter of a sugar molecule and Avogados number. He proposed that light is composed of separate packets of energy called quanta or photons. He had speech difficulty in early childhood. Has a 15% larger brain than anyone else.

Niels bohr

October 7, 1885 - November 18, 1962

Proposed a theory for the hydrogen atom based on quantum theory that energy is transferred only in certain well defined quantities. Known best for his substantial contributions to quantum theory and his Nobel prize winning research on the structure of atoms. Created atomic model. He was on a college soccer team and during WWll, offered Jewish Scientist a place to live and work.

Erwin Schrodinger

1887 - 1961

He was an Australian physicist. Took the Bohr atom model a step further. Used mathematical equations to describe the likelihood of finding an electron in a certain position.

James Chadwick

October 20, 1891 - July 24, 1974

Discovered neutrons in atoms. Joined Rutherford in accomplishing the transmutation of other light elements by bombardment with alpha particles and in making studies of the properties and structure of atomic nuclei. He had twin daughters and hobbies included gardening and fishing.

Louis De Broglie

August 15, 1892 - March 19, 1987

Groundbreaking contributions to quantum theory known as de Broglie hypothesis. Predicted wave nature of electrons. Did not marry and awarded the 1929 Nobel prize for physics.

Werner Heisenberg

1901 - 1976

Best known for his uncertainty principle and theory of quantum mechanics which he published at the age of 23 in 1925. He was awarded the Nobel Prize for Pysics in 1932 for his subsequent research and application of this principle.