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500 BCE
Greeks
It all started with the Greeks, around 2,000 years ago. In the earlier years of them, they believed that everything in the universe was made of four elements: Earth, Air, Fire, and Water. It should be noted that the object/substance is a combination of these, and the elements don't exist in a pure form. The ultimate goal of the elements is for them to take their proper place in the universe; Earth in Earth, Water on Earth, (above), Air above water, and Fire on top. -
Period: 500 BCE to
History of the Atom
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460 BCE
Democritus-Birth
Democritus is born into a wealthy family in Abdera, Greece. -
400 BCE
Democritus-Atoms
Democritus says that “all matter was formed of different types of tiny discrete particles”, and the properties of those particles determined the properties of its matter. He comes up with the ideas of air between atoms, they're completely homogeneous solids, have no internal structure, have different sizes and shapes, and are indestructible. Democritus did not bother to carry out any experiments to prove his theory, but based it on observations -
360 BCE
Democritus-Death
Democritus dies in 360 BCE, at 90 years of age in Athens, Greece. Perhaps, like he believed, he will become a mud person, and then a wild animal, and eventually human again. -
Antoine Lavosier-Birth
Antoine Lavosier is born in Paris, France -
John Dalton-Birth
John Dalton is born in 1766, in Eaglesfield, England. -
Lavosier-Metric System and Hydrogen
Lavosier helps introduce the Metric System and recognizes hydrogen. -
Lavosier-The Law of Conservation of Mass
In 1789, he introduces the Law of Conservation of Mass, that matter is conserved in a chemical reaction. To prove this, he put a burning candle inside a sealed glass jar, and as the candle melted the weight of the jar and the contents stayed the same mass. -
Dalton-Color blindness
Dalton describes his colorblindness- how he confuses scarlet with green and pink with blue. Little does he know his observations will help the rest of the colorblind world develop. -
Lavosier-Execution
Lavosier is executed after being found guilty of fraud during the French Revolution on May 8, 1794. -
Dalton-Law of Partial Pressures
His law of Partial Pressures states that the total pressure of a gas mixture = the "sum of the partial pressures of the component gases" Dalton did research about properties of compounds and showed that any one compound has “the same elements in the same whole-number ratio” and different compounds consist of different elements/ratios. Dalton said that this can only happen “if elements are made of separate, discrete particles that cannot be subdivided.” -
Dalton-Atomic Theory
Dalton believed that elements are made of tiny spheres, (atoms), and that the atoms in one element are identical, but atoms in separate elements are different. He also says that compounds are small, fixed, whole number ratioed atoms, and that atoms cannot be created or divided into smaller particles. -
Dalton-Death
Dalton dies on July 27, 1844 in Manchester, England. -
J.J Thompson-Birth
J.J Thompson is born in Cheetham Hill, Manchester, England, in 1856. -
Max Planck-Birth
Max Planck is born in Kiel, Germany in 1858 -
Marie Curie-Birth
Marie Curie is born in Warsaw, Poland in 1867. -
Robert Millikan-Birth
Robert Millikan is born in Morrison,IL in 1868. -
Ernest Rutherford-Birth
Ernest Rutherford is born in 1871 in Brightwater, New Zealand. -
Planck-PhD at 21
Planck receives his PhD at 21 from the University of Berlin. -
Albert Einstein-Birth
Albert Einstein is born in 1879, in Württemberg, Germany. -
Niels Bohr-Birth
Niels Bohr is born in Copenhagen, Denmark in 1885. -
Erwin Schrodinger-Birth
Erwin Schrodinger is born in 1887, Vienna, Austria. -
James Chadwick-Birth
James Chadwick is born in Bollington, UK in 1891. -
Louis de Brogile-Birth
Louis de Brogile is born in 1892, Dieppe, France. -
Thompson-Electron Discovery and Cathode Ray Tube Experiment
Thompson announces the “discovery” of the electron, and explains their negative charge with the cathode ray tube experiment. In this experiment, electricity passes from the cathode to the anode, a small bit of electricity passes through hole in the anode, + charged metal plate on top and - charged metal plate on bottom. -
Rutherford-Alpha and Beta Radiation
Rutherford discover two new types of radiation- alpha and beta. -
Planck-Quantum Theory
He found that black bodies always radiated the amount of energy proportional to the electromagnetic frequency that they absorbed, and that the energy was always emitted in “tiny, discrete packets' '. He called these packets of energy a “quantum” of energy. Based on this discovery, a new branch of science, “quantum mechanics'', was born. This focuses on the nature of tiny particles, like protons and neutrons. -
Werner Heisenberg-Birth
Werner Heisenberg is born in 1901, Wurzburg, Germany. -
Curie-First Nobel Prize in Physics.
Marie Curie receives her first Nobel Prize in Physics. -
Marie Curie-Atoms & Radiation
She discovered that radioactivity does not depend on how atoms are arranged into molecules, but instead the atoms themselves. To prove this, she tested all known elements at the time to determine if they could make air conduct electricity better or if only uranium could do so. She then was able to make the claim that the rays were not dependent on its form but the atomic structure. -
Thompson-Plum Pudding Model
Oddly enough, he liked to call electrons "corpuscles" , and believed atoms were a sea of positive “ooze”, with negative corpuscles floating around it, (the plum pudding model). -
Einstein-E=mc2 & Exsistence of Atoms
In his 1905 paper, he mathematically proved the existence of atoms, along with E=mc2, the foundation for modern atomic energy. Einstein explained Robert Brown's moving pollen seeds in water by detailing how if the tiny particles were suspended in liquid, the atoms in the liquid would make the particles jiggle, and predicted the motions of the particles and how they could be observed under a microscope. -
Einstein-Elaboration
In May 1908, Einstein elaborated on his 1905 paper and suggested how to test his theory. In the same year, Jean Perrin was able to conduct experiments to prove Einstein's theories, confirming the existence of material atoms. Einstein's contributions were more based on probability, statistics, and mathematics than traditional experiments. -
Millikan-Oil Drop Experiment and the charge of the Electron
In order to determine the charge carried by electrons, a chamber sprays a thin mist of oil, where the now negatively charged droplet is pulled upwards by the + charged plate while gravity pulls it down, to where the electrostatic and gravitational forces control where the droplet flows. The goal was to balance these forces to stop the droplets midair, so that both the forces and the droplets mass could be measured, revealing the charge of the electron. -
Millikan-Professor
When he became a professor in 1910, he made a curriculum along with many textbooks where he stressed the importance of lab-based learning in high school and college physics. -
Rutherford-Gold Foil Experiment and nucleus/electrons.
In the gold foil experiment, a source with a shield of lead reflects alpha particles onto a piece of gold foil, surrounded by a deflector. This helped us learn that the nucleus is positive, most of the mass in the atom is in the nucleus, the nucleus is dense and small, the atom is mostly empty space, and the electrons are tiny compared to the nucleus. -
Rutherford's model of the atom.
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Curie-Nobel Prize in Chemistry
Marie Curie wins her second Nobel Prize in Chemistry. -
Bohr-Bohr Model
He was able to develop his model after observing the way hot hydrogen glows and gives off light. Based on the way an incandescent light bulb is lit and the filament heats up, it gives off different wavelengths; and how hydrogen gas heats up and becomes incandescent, it gives off a different wavelength. Bhor thought that this happens because electrons adopt specific atomic energy levels instead of any possible levels. -
Chadwick-Prisoner of War
He lived through many wars, including WWI, WWII, and the Korean War. He was a prisoner during WWI for 4 years, but was able to continue his research due to sympathetic German soldiers. -
Einstien-Uncredited Author and Incest.
It's suspected that Einstein's first wife. Mileva Maric, was an uncredited author in his most important discoveries, and was confirmed to have dated and married his first maternal cousin, Elsa Einstein. -
Bohr-Manhattan Project
Because of Bhor's research in the Manhattan Project, the atomic bomb was possible. -
Brogile-Theory of Electron Waves
His doctoral was dedicated to this, stating that “electrons behave as waves'', and therefore all particles and objects are “associated with matter waves'' Putting together both Planck's equation and Einstein's special realtivity, he calculated the length of the matter waves depending on the velocity and mass. He concluded that the whole world is quantum, not just light. His theories were supported by Albert Einstein, before they were able to be proven and accepted by the scientific community. -
Schrodinger-Wave Equation
He was able to create a wave equation formula that accurately predicted the energy levels of electrons in atoms.
Schrodinger was able to further the Bohr model based on Brogile's theory of electron waves, combined with the wave function equation. He imagines the electrons as waves and describes the orbitals where they're most likely to be found. It goes from a 1-D model to a 3-D one on a plane, and gives a possible location. -
Heisenberg-Uncertainty Principle
The Heisenberg Uncertainty Principle states that a particle's position and momentum cannot be known exactly.
To show this, he conducted a “thought experiment”, where he considered using a gamma ray microscope to measure the position of an electron. The illumination would change the momentum in an uncertain way, and a higher resolution microscope would give the electron more “kick”. He reasoned, the more you try to measure the position, the more uncertain the momentum becomes. -
Chadwick-Discovery of the Neutron
Until his experiment, the atom was only known to consist of a + charge nucleus surrounded by enough - charged electrons to make the atom neutral, and was thought to contain protons and electrons. Then, in 1932, Chadwick conducted his experiment where he “bombarded” Beryllium with alpha particles from Polonium's natural radioactive decay. The radiation that was able to go through a lead shield, and was unable to be explained with presently existing particles. -
Chadwick-Model of the Atom
Chadwick's new model of the atom along with the discovery of the Neutron. -
Curie-Death
Marie Curie dies in 1934 in Passy, France. -
Schrodinger-Schrodinger's Cat Paradox
He developed the Schrodinger's Cat paradox, which illustrates the paradox of quantum superposition. -
Ernest Rutherford-Death
Ernest Rutherford dies in 1837, Cambridge, England. -
Thompson-Death
J.J Thompson dies in Cambridge, UK, in 1940. -
Planck-Death
Planck dies in 1947. -
Millikan-Death
Robert Millikan dies in 1953, San Marino, California. -
Einstein-Death
Einstein dies in 1955, Princeton, New Jersey. -
Schrodinger-Death
Schrodinger dies in 1961, Vienna, Austria. -
Chadwick-Death
James Chadwick dies in 1974, Cambridge, UK. -
Heisenberg-Death
Heisenberg dies in 1976, Munich, Germany. He was interested in piano and rather gifted, and sometimes played with Albert Einstein. Eventually, he became more interested in science than music. -
Brogile-Death
Brogile dies in Louveciennes, France.