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Democritus
Democritus is an Greek Scientist who lived in Thrace, Greece from 460-370 BC. He is the first to theorise that atoms exists and everything was made up of matter. He said that atoms are always moving and indestructible and created the first basic model of the atom. He based his theory off of observations and natural curiosity, and research of Leucippus, an ancient Greek Philosopher. -
Antoine Lavoisier
Antoine Lavoisier is a French Scientist who lived from Aug. 26, 1743 - May 8, 1794 in Paris, France. He changed chemistry when he created the first Law of Conservation of Mass, named the elements Hydrogen, Carbon, and Oxygen and discovered that Water was compounded of Hydrogen and Oxygen. His experiment involved burning different compounds to explore the product elements. Unfortunately, Lavoisier was framed during France’s Reign of Terror, and beheaded at the guillotine, however his work and con -
John Dalton
John Dalton is an British Scientist who lived in Cambria, UK from Sep. 6 1766 - July 27 1844. Dalton theorised that matter is composed of extremely small particles called atoms; atoms are indivisible and indestructible; atoms of a given element are identical in size, mass, and chemical properties; atoms of specific elements are different than those of other elements; and in a chemical reaction, atoms separate, combine and/or rearrange. Dalton’s model of an atom is the first known model in histor -
J.J. Thomson
J.J. Thomson is a British Scientist who lived in Cambridge, UK from Dec. 18,1856 - Aug. 30, 194 Thomson contributed to the Atomic Theory when he discovered the Electron. His experiments studied the electric discharge in a high vacuum cathode-ray tube. His model of the Atom, the “Plum-Pudding Model”, updated Dalton’s model as it contained electrons scattered throughout the atom. -
Max Planck
Max Planck is a German Scientist who lived in Berlin, Germany from April 23, 1858 - Oct. 4th, 1947. Planck changed Physics when he stated the Quantum Theory, which is the relationship and processes of energy and frequency of radiation. His experiments studied the distribution of energy in radiation. -
Robert Millikan
Robert Millikan is an American Scientist who in Chicago, IL from March 22, 1868 – Dec. 19, 1953. Millikan measured the charge of an electron which also proved the electron mass from Thomson’s Charge to Mass Ration. He used the Oil-Drop experiment to find the charge of an electron -
Ernest Rutherford
Ernest Rutherford is a British Scientist who lived in Cambridge, UK from Aug. 30, 1871 - Oct. 19, 1937. He proved the center of an atom contained a small, dense nucleus and he was the first to theorize about the Neutron. Rutherford used the Gold-Foil Experiment to discover his model of the Atom. Rutherford’s Model of the Atom contained a dense, positively charged nucleus with electrons moving around the nucleus. -
Niels Bohr
Niels Bohr is a Danish Scientist who lived in Copenhagen, Denmark from Oct. 7th, 1885 - Nov. 18th, 1962. Bohr made an important discovery in his theory for hydrogen atoms based on quantum theory that energy is only transferred in different levels of electrons. His Model of the Atom, the “Planetary Model” is the one we used today. -
James Chadwick
James Chadwick is a British Scientist who lived in Cambridge, UK from Oct. 20th, 1891 - July 24, 1974. He made a significant and crucial discovery to the atomic theory when he discovered the Neutron. Chadwick’s experiment shot radiation particles at wax to find neutral particles being emitted. James Chadwick make the next step in forming the Atomic Theory.
