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Atomic Theory Timeline

Third period

Yisela Flores

on 16 September 2013

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Transcript of Atomic Theory Timeline

J. J. Thompson
Thompson made a theory that these electrons were the very building block of atoms. He called these building blocks "corpuscles". He discovered these negatively charged particles using the cathode ray.
Niels Bohr
Bohr made a model of a hydrogen atom that included the electrons of the atom. He created a formula for calculating the location of these lines and the mass of the electrons. Later in his life, he escaped to America where he worked with other scientists on the Manhattan Project.
Sir William Crookes
William Crookes discovered the part of the atom known as the electron. He discovered this electron by reconstructing the Cathode Ray. He noticed a green light that was produced by radiation and because the negative charge caused the light to appear, it led to the discovery of the electron.
Robert Millikan
As a Professor at the University of Chicago Robert and his graduate student Harvey Fletcher conducted experiments looking to discovery the charge of electrons.
Ernest Rutherford
Ernest Rutherford, one of the great scientists during the 19th and 20th century contributed to atomic theory by discovering the extremely dense part of the atom which included the nucleus. His discovery also proved that most of the atom was made up of empty space. His contributions to atomic theory have truly changed the way we will describe an atom forever.
Atomic Theory Timeline
G. J. Stoney
Dalton's atomic theory has a few main points. Elements are made of extremely small particles called atoms. Atoms cannot be subdivided, created, or destroyed. Atoms of given element are identical in size, mass, and other properties while atoms of different elements differ in these aspects. Atoms of different elements combine in simple whole-number ratios to form chemical compounds. And last, when a chemical reaction occurs, the atoms are combined, separated, or rearranged.
John Dalton
Mendeleev published the periodic table of elements of all the known elements at the time and predicted several new elements to complete the table. On the periodic table, the elements, if arranged according to their atomic weight, exhibit an apparent periodicity of properties. The elements which are similar regarding their chemical properties have atomic weights which are either of nearly the same value or which increase
Dmitri Mendeleev
Max Planck was a German physicist known for his work in quantum theory for which he earned a Nobel Prize. Plank's quantum theory basically says that radiant energy can only be emitted or absorbed in small quantities. He gave the name quantum to the smallest quantity of energy that can be emitted (or absorbed) in the form of electromagnetic radiation.

Max Planck
Aristotle was a very influential Greek philosopher. Aristotle dismissed the idea of the atom, and no other influential work was done on the atom until 2000 years later in the 1800's.
Albert Einstein
Einstein was visiting the United States when Hitler came to power. Instead of going back to Germany, Einstein stayed in the United States and became a naturalized citizen in 1940. That same year, Einstein wrote a letter to President Roosevelt warning him of the potential of new and powerful bombs being constructed. This prompted the beginning of the Manhattan Project. Einstein was one of the leaders in the project, and he is also known for his theory of relativity. Einstein also had much to do with the development of modern quantum theory.
Friedrich Hund
Hund spent much of his time in Physics. Specifically in quantum mechanics, modifying the current electron configuration. He published Hund's rules with a main purpose of making the electron orbit around the nucleus of the atom.
Michael Faraday
Royal Medal 1835 & 1846
This English scientist contributed to electromagnetism and electrochemistry. Thanks to Faraday we now have a foundation for the electromagnetic field.
Henri Becquerel
After the invention of X-Rays, Becquerel suggested that some radioactive materials may emit X-Rays naturally. But after experimenting with things like Uranium salt, he reported that X-Rays were emitted naturally as radiation from the Uranium salts. What followed was an intense period of research in radioactivity trying to find other substances like it.
Lisa Meitner, Otto Hahn, & Fritz Straussman
These three scientists in 1938 were able to split Uranium atoms in a process called fission.
During the early 1900s, scientists were just beginning to understand the structure of atoms. Nagaoke rejected the idea that electrons were included with protons in an atomic "sphere". He said that there is no way that positive protons can exist that close to negative electrons. Instead, he said that the atom had a massive nucleus and the electrons must orbit around it. He compared it to the rings of Saturn.
Hantaro Nagaoke
Chadwick devoted his early life to changing the accepted idea of the atom. It was believed that atoms only contained protons and electrons. This gave atoms the correct mass, but it gave the atom the wrong "spin". Spin is the angular momentum that the atomic nuclei followed. Chadwick soon began experimenting with what he called Neutrons. Later in his life, he worked on the Manhattan Project.
James Chadwick
Schrodinger dedicated his life to quantum mechanics. He studied the work of Plank and Bohr before he published an article on wave mechanics. This article is one of the most celebrated in the 19th century, and soon after, Schrodinger published a second and third article. The third paper covered many popular quantum problems and their explanations with approaches similar the that of Wener Heisenberg.
Erwin Schrodinger
Louis de Broglie
Louis de Brogile made ground breaking contributions to quantum theory, which included advancements in, matter with his discoveries which stated that all matter has wave properties. His new-found concept was named wave-particle duality or the de Brogile hypothesis.

As Henry Moseley radically changed the empirical and chemical concept of atomic number, he developed his Law of X-ray Spectra, which also stemmed into his justification for the way in which he organized chemical elements.
Henry Moseley
400 B.C.
340 B.C.
Democritus developed a hypothesis of the atom in 400 B.C. He is the first recorded person to support the idea that all things are made of small things called atoms.
Marie Curie
The French-Polish physicist made advancements on the development of X-rays in which she discovered that radiation occurs not only on molecular level but also at the atomic level. She devoted the rest of her life to research and radioactive elements. Unfortunately her and her colleagues were unaware of radiation poisoning. Ironically Curie died from anemia, a symptom of the over-exposure to radiation.

regularly. Also, certain characteristic properties of elements can be foretold from their atomic weights. There were other important information about the periodic table, but those are the main ones.
Werner Heisenberg
Modern Physics settles on Plank's Scale instead of his, however he published his theory of electrons to the world in 1891. He also named the electron with consideration going to its negative electrical charge.
1920 - 1950
Developed the uncertainty principle while working in quantum mechanics. He was summoned to Albert Speer's office during Hitler's reign to discus the production of a nuclear bomb. He and others in the "Uranium Club" worked during the rest of the war until arrested by Allied special forces, and transported to England for safe keeping. Heisenberg worked in Chemistry for the rest of his life.
His famous experiment that he conducted was the oil-drop experiment, with this experiment they discovered the charge of the electron as well as the electron mass.
Robert in 1923 stole credit for the discovery and won the Nobel Prize for Physics. Harvey made an agreement with Robert to keep it a secret to let Robert have the credit, until his death when he published t was him that made the discovery and not Robert.
Hahn had won the Nobel Prize because atomic bombs were based off his basic discovery, Meitner thought she too should have won the Nobel with Hahn and continued her nuclear research. While Straussman went to the study of nuclear chemistry.
by:Yisela Flores
3th period
Full transcript