-
550 BCE
Asharya Kanada - 2600 years ago
Known as "the actual father of atomic theory". One of the first to realize the atom is indestructible. He used real-life examples to emphasize his work. Figured out that atoms can't break down further and they must have bonded together to resist falling apart. Even though Acharya developed this solution much earlier, most people disagree and say that it cannot be placed in the same league as Dalton's theory and therefore Dalton is still the original father of Atomic Theory. -
440 BCE
Discovery of the Elements - Empedocles
Proposed the theory that everything was made up of four elements. These elements would shape everything on earth and could be combined to make all products on earth. There was positive feedback on this theory, but over time as more elements were discovered this theory was flawed because there were more than just the four elements. This strengthened atomic theory because you only learn from mistakes and that is how you can adapt. Lived from approximately 490 - 430 BC -
400 BCE
Democritus Discovery
Discovered how everything was made up of matter, and matter consisted of particles which are indestructible and unchangeable. His model was solid and outlined how all atoms vary in size, shape, mass position and arrangement where a void can exist within the atom. This was the second theory proposed which changed the old way of thinking about atomic theory. Democritus lived from 460 - 370 BC and his greatest contribution was the Atomic Theory Discovery. -
John Dalton - Atomic Theory Definition
Formulated the first modern-day idea of atoms. Discovered and produced the 5 main points of atomic theory we still study today. Those points are:
Everything is composed of atoms, they are invisible and can't be destroyed. All atoms are identical. Different elements' atoms vary in mass and size. Compounds are produced from combinations and a CR rearranges the atoms in the reactants and compounds. Dalton lived from September 5 or 6, 1766 to July 27, 1844. -
J.J Thomson - Plum Pudding Model
Discovered and theorized electrons within atoms. Thomson discovered this by doing tests and using Cathode Rays He discovered the presence of electrons in 1897 and proposed the idea in 1904. Theorized how in the nucleus there are negatively charged newtons surrounded by one glob of positively charged pudding (the nucleus). Thomson was born on December 18, 1856, and died on August 30, 1940. -
Planck Theory Explained
Planck Theorized and developed the Quantum Theory. This theory would later win him the Nobel Prize in 1918. This theory explains and identifies the intensity of the light based on electrons of the substance. This light is unique for every electron and is based on the properties of the substance. This relates to the properties of elements which is apart of atomic theory because every element is different. Planck was born in April 1858 and died in the month of October in the year 1947. -
Marie Sklodowska Curie - X-rays and radium and polonium
Marie was a female role model and a leading scientist in Atomic Theory. Marie Discovered X-rays by noting that uranium casts weaker rays than X-rays. She also had a huge involvement with the war (WWI) by using her X-ray machines to help wounded soldiers. The emergency vehicles were called "Little Curries". This relates to atomic theory because the rays within the machines that Currie theorized come from the atomic structure of the elements. https://www.biography.com/scientist/marie-curie -
Hantaro Nagaoka
Known for the Saturnian atomic model. This was unique because it had a large charge of positive atoms in the center and a ring of electrons outside of the nucleus. He was later proven wrong and moved onto determining the actual arrangement of electrons in 1908. This is interesting because even though he had his own model of the atom when renounced of his model, he didn't try to prove his own model, but rather moved on with life. Born in August 1865 and died in December 1950 in Japan -
Albert Einstein - Theory of Relativity
Einstein published his theory of relativity in 1905. This theory is the most important because he was able to prove the existence of electrons using an ordinary microscope. This is one of the most important discoveries ever this is because it explains many different questions people have about astronomy and physics. This relates to Atomic Theory because everything is relative and doesn't have fixed values. This proves how the energy of electrons are always changing -
Rutherford Contribution
Presented Bohr Rutherford model in 1913. This was different because all models before had no notion of electrons within the atom. Ernest Rutherford also stated that electrons occur outside the nucleus orbit the nucleus of the atom within orbitals. Ernest Rutherford and Niels Bohr are the two scientists who theorized and produced this model. Rutherford lived from August 13th, 1871 until October 19th, 1937. -
Niels Bohr Idea
Niels Bohr worked alongside Ernest Rutherford in the creation of the Bohr-Rutherford Model. This model was unique because all previous models did not include the presence of electrons and were only about the nucleus of the atoms. He theorized how electrons should move around the nucleus in theorized patterns. When the electrons jump from a low orbital to a higher orbital a light is produced and that color is different for every atom. Bohr lived from October 1885 to November 1962 -
Satyendra Nath Bose -
Discovered while working alongside Einstein and proposed a condensate theory. This theory was called the "Bose-Einstein" theory which is another name for one of the two subatomic particles. He discovered the "God" particle through the use of this theory. This relates to Atomic Theory because everything is made up of matter and knowing the subatomic particles and how they operate can better help our understanding of AT.
Satyendra Nath Bose was born on January 1894 and died on February 1974 -
DeBroglie Theory
Louis theorized a theory which stated that anything that is moving/all matter has wavelengths and is able to exert waves of some sort. This is super important because even Einstein one of the greatest scientists ever agreed with DeBroglie's theory and applied it to his own idea. This relates to Atomic Theory by trying to find out the values of the electrons within the matter. This gives us a better understanding than we had. DeBroglie lived from the 15th of August 1892 to March 19, 1987 -
Wolfgang Pauli - Pauli Principle
Wolfgang in 1925 introduced a new number for electrons. This number was: that no two electrons could have identical sets in quantum numbers. This is key because it shows how electrons are always moving in separate paths and that they will never impede one another. This principle could also be shown in protons and neutrons later on in the discovery of Atomic Theory. Pauli later won the Nobel Prize in 1945 for his discovery. Wolfgang Pauli died in December 1958, in Zurich, Switzerland -
Schrodinger Atomic Theory
Erwin identified the Bohr Rutherford Model and continued the idea by trying to find the positioning of the electrons. His Theory could not truly identify and calculate the positioning but rather uses the odds to predict where the electron is situated. This was massive because it gave scientists a more specific view on Atomic Theory and limits possibilities of the electron location. Schrodinger lived from 1887 - 1961 -
Heisenberg Theory - Formulation of Quantum Mechanics
Werner expanded our knowledge of Quantum Mechanics by introducing his uncertainty principle. This was a principle that stated the velocity and position of an electron cannot be measured at the same time. This is contradictory to nature but was verified by scientists. This is related to AT because you can never truly know where an electron has ended up. That is the most difficult part of Atomic Theory because there is never a clear solution to this problem. Werner died in February 1976. -
James Chadwick - Discovery of Neutrons
Chadwick discovered the Neutron through a series of tests. The test that proved the presence of neutrons was a test which included scattered data to calculate the mass of the neutron. Up until 1932, the presence of protons and electrons was known, but no one ever thought there was another key particle of the atom, which was the neutron. Chadwick won the Nobel Prize in 1932 for his discovery. James lived from October 1891 to July 1974 -
Irene Joliot Curie - Artificial Radioactivity
Daughter to Marie and Pierre Currie (creator of X-ray) Produced a theory which stated that artificial radioactivity can be artificially produced when you combine 2 or more stable elements together. Allowed for much more research to occur with the knowledge of this type of reaction. These radioactive isotopes could be made relatively inexpensively. She also had a big involvement in the war. She worked with x-ray machines while helping soldiers recover. -
Dorothy Crowfoot Hodgkin - X-ray crystallography
She was able to determine the three-dimensional shape of molecules using X-ray technology. She used this technology only for complex organisms vital to humanity because those were the most important to how we humans are able to live on earth. This process was very tedious and required multiple mathematic calculations to be done successfully. Dorothy and her husband, Thomas both held high professional roles at the University of Oxford, where they raised three children. -
Lise Meitner - Nuclear Fision
Lise is not only an amazing scientist but also a peacekeeper of the world. Nuclear fission is when a particle and a nucleus come into contact and splits spontaneously and the product is energy. This is what Lise determined, that the product of nuclear fission causes a lot of energy afterward. Her technology had the power to create the nuclear bomb and in the second world war, she created this technology and war leaders, felt it was necessary to create a nuclear bomb. She acted against the idea. -
Rosalind Franklin -
Franklin's specific field within Atomic Theory was discoveries towards the molecular structure of coal and carbon. This is important because it relates to carbon fibers and how they relate to the function of power plants. Maurice Wilkins gave a copy of Franklin's report to an American James Watson, to claim the work as his own. Rosalind would never be able to claim that work and would have been a huge scientist if she wasn't cheated on by Wilkins. She sadly passed away at age 37 from cancer. -
Robert LeRoy - Intermolecular forces and LeRoy Bernstein Principle
LeRoy was passionate about chemistry and enjoyed studying intermolecular forces. He used Computer models to determine the forces that occur within atoms. The principle he developed was called the LeRoy Radius, this was a principle that determined the distance of the intermolecular forces between atoms. These concepts are both very important to Atomic Theory because schools all are over the world use these principles in their labs. LeRoy was born on September 1943 and died in August 2018 -
Richard Bader - Electron Density
Richard contradicted a traditional theory (Bohr-Rutherford) of how electrons are in orbitals around the nucleus. This is bold and unusual because it goes against ancient traditional models. He preached how electrons follow no orbitals. He also found out how the density of electrons determines the properties and behaviors that atoms have. Bader was born in October 1931 and died in January 2012 -
Ronald J. Gillespie Valence Shell Electron Pair Repulsion Theory
Gillespie developed a theory to determine the geometry of a compound. The principle needs a central atom for the theory to work. An example is CH4, this is because there is a carbon atom which is in the middle of the compound and there are four hydrogens that are all bonded to the Carbon. The hydrogens have a (+) charge and all repel each other, this causes a tetrahedron shape. This relates to AT because everything in Chemistry is based on atoms and it is important to know the shape.
