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Conservation of Mass
Antoine Lavoisier discovers that during a chemical reaction, matter can not be created or destroyed becoming the law of the conservation of mass. -
Gay-Lussac's Theory
J.L. Gay-Lussac formed a theory that stated the volumes of gases are in the ratio of small whole numbers. -
Dalton's Theory
In 1803 John Dalton Developed his theory of the atom stating,
a) All matter is made of atoms. Atoms are indivisible and indestructible.
b) All atoms of a given element are identical in mass and properties
c) Compounds are formed by a combination of two or more different kinds of atoms.
d) A chemical reaction is a rearrangement of atoms. -
Definite Proportions
Joseph Proust found that the elements in a substance were always found in the same proportion as long as the substance remained constant. -
Uranium's Film
French Scientist Henry Becquerel discovers a photographic fil around the element Uranium. -
Radiation from Elements
Marie and Pierre Curie discovered that the elements Radium and Uranium give off radiation. -
Cathode Rays
Scientist J.J. Thomson discovered that cathode rays were made up of electrons. -
Quantum Theory
Planck believed that energy was given off in little packets called quanta. He also discovered that the frequency was related to the energy of the light emitted. -
Einstein's Hypothesis
Einstein theorized that energy and mass were equivalent through the formula E=MC2 or mass times the speed of light squared equals energy. -
Milikan's Measurement
American Scientist Robert Andrews Millikan correctly measured the charge of an electron. -
The Nucleus
Physicists Rutherford, Bohr, Geiger, and Marsden found that the atom was composed mostly of free space and that some type of core at the center of the atom held the protons and neutrons which would later be known as the nucleus. -
Wavelength of X-Rays
English Scientist Henry Moseley found that the wavelength of the X rays was dependent on the metal used as an anode. -
Electron Orbits
Bohr discovered that electrons occupied certain orbital paths and that they could absorb or emit energy only in integers. -
The Third Particle
English Physicist Lord Rutherford predicts that there is a third atomic particle. -
Neutron Discovery
English Scientist James Chadwick finds that there are other high energy particles called neutrons with no atomic mass that also had around the same mass as the proton.
