June 30, 2021
For educational institutions
1st Nine Weeks Honor Project Chemistry
⟶ Updated 18 Oct 2018 ⟶
List of edits
Gamma radiation is found to penetrate more than x-rays observed by Paul Ulrich Villard.
X-rays are recognized to be lethal to mammals.
Observations conclude radiation can cause organ and tissue damage.
X-rays are linked to cancer in physicians.
Hans Geiger exhibits his radiation detector.
Regulations are proposed by the British Roentgen Society to protect workers from radiation.
The American Roentgen Ray Society puts together the first committee for x-ray protection.
Arthur Mutscheller proposes the first tolerance dose for radiation.
Charles Lauritsen makes an x-ray machine with high voltage that contributes to radiation therapy.
Lise Meiter works with Otto Hahn on splitting a uranium atom which encourages the production of the atomic bomb.
"The world's first nuclear reactor is activated in Oak Ridge, Tennessee."
Oak Ridge National Laboratory and Argonne National Laboratory study the effects of radiation.
After many atomic bombs during World War II and the consequences of radiation in people result, "A National Academy of Sciences Committee issues a report asserting no safe threshold for radiation exposure."
Democritus is the first person to suggest the idea of an atom
John Dalton comes up with the atomic theory.
Michael Faraday discovers atoms have an electric charge.
Sir William Crookes studies the effects of a cathode ray tube experiment.
Marie and Pierre Curie discovered radium and polonium, and discovered beta particles are negatively charged.
Wilhelm Roentgen discovered x-rays, formerly known as Roentgen rays, while experimenting with cathode rays.
Henri Becquerel discovered radioactivity when studying the fluorescent properties of uranium salts; Rutherford went further and experimented and calls the rays (radioactivity) alpha and beta
Becquerel discovered electrons and beta particles are the same thing.
Becquerel and his two students Marie and Pierre Curie shared a Nobel Prize for Physics for their studies in spontaneous radiation.
When experimenting with a cathode ray tube, J.J. Thomson discovered the electron.
Rutherford makes known radioactivity is caused by the breakdown of atoms.
Rutherford proves Thomson's atom model is incorrect and uncovers his greatest scientific discovery: the nucleus.
Niels Bohr developed a new model of the atom, "patterned on the solar system." It's called the Bohr model or the Rutherford-Bohr model.
Rutherford recognizes protons in the nucleus.
Rutherford causes an artificial nuclear reaction in a stable element.
Erwin Schrodinger develops the quantum mechanical model of the atom.
James Chadwick uncovers the neutron.
Cockroft and Walton first split an atom in a particle accelerator.
Glenn Seaborg recognizes lanthanides and actinides, placed below the periodic table.
Antoine Lavoisier groups elements based on their components into categories of gases, metals, non-metals, and earths.
Johann Dobereiner recognizes triads of elements and comes to the conclusion that components of the middle element could be predicted by the components of the other two.
Alexandre Beguyer de Chancourtois contributes the telluric screw which plotted an element's atomic weight on the outside of a cylinder.
John Newlands comes up with the Law of Octaves, seeing similarities between elements that differed by 7 and comparing it to octaves in music.
Julius Lothar Meyer creates several periodic tables from 1864- 1870.
Dmitri Mendeleev creates an accurate periodic table.
Henry Moseley finds a way to measure atomic number.
Phosphorus is first discovered by Hennig Brand when trying to create an object that was able to turn metals into pure gold.
Robert Boyle's discovery of phosphorus goes public.
At least 47 elements are discovered.
Sir William Ramsay and Lord Rayleigh uncover noble gases, which were added to the periodic table as group 0.
Bohr discovered electrons move around the nucleus in orbitals. When a electron moves from one orbital to another, radiation is emitted.
The Curies make public the existence of the element radium. Gamma rays are made known by Paul Ulrich Villard.
About & Feedback