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492 BCE
Democritus
He believed that all matter is made of substances that can't be divided. He was one of the creators of the atom, he named it after the Greek word "Atomos" which means indivisible. His theory was often questioned even though he was one of the founding scientists of the atom. -
Period: 492 BCE to
Atomic Scientists
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Isaac Newton
He proposed that there where small solid masses in motion. He believed that it was a mechanical universe. In short he believed that there were small pieces "swimming" around. -
John Dalton
He proposed that everything is made up of atoms. He also said that different elements atoms are different sizes and mass. -
Michael Faraday
Studied the effects of electricity on solutions. He coined the term "electrolysis" as a splitting of molecules with electricity. He developed laws of electrolysis. -
Julius Plucker
He built the first gas discharge tubes. A Cathode ray tube. Which helped many scientists discover more about the atom. -
Lothar Meyer
He published his own periodic table. His published table showed a graph relating atomic value and atomic number and clearly showing the relationships of the elements. -
Dmitri Mendeleev
He found that if you put all the known chemical elements in order of increasing atomic weight. The resulting table displayed a recurring patterns, or periodicity, of properties within groups of elements. In his periodic table he left empty spaces where he believed unknown elements would find there place. -
James Clerk Maxwell
He came up with the concept of electromagnetic radiation. He also created multiple math equations based on Michael Faraday's observations. He was even complimented by Einstein saying “the most profound and the most fruitful that physics has experienced since the time of Newton.” -
Sir William Crookes
He applied R.W. Bunsen and G.R. Kirchhoff technique on selenium compound and discovered Thallium in seleniferous deposits. Crookes discovered the principle of the Crookes radiometer, a device that converts light radiation into rotary motion. -
Eugen Goldstein
He discovered canal rays also called positive rays. These are positively charged ions that are accelerated toward and through a perforated cathode in an evacuated tube. This discovery led to the design of cathode rays. -
G.J. Stoney
He estimated the number of molecules in a volume gas under standard conditions. His method was sound though his result was incorrect because of an erroneous idea of the number of atoms in a gram of hydrogen. -
Wilhelm Roentgen
While experimenting with a cathode ray and an electric current. He observed that a nearby piece of barium platinocyanide gave off light when the tube was in use. So he theorized that some unknown radiation came off the tube and caused the barium to light up.With further investigation that revealed paper, wood, aluminum, and among other materials transparent to this type of radiation. He called it x-radiation and took this first x-ray. -
Henri Becquerel
He did more experiments with X radiation. He tested with crystals. He thought that there was a caption between invisible x radiation and visible light that we can see. -
J.J. Thomson
He came up with the plumb pudding model. His model showed that there was a positive nucleus and that the negative particles stuck to the positive nucleus. He discovered the electron. -
Ernest Rutherford
Rutherford was a key scientist in the study of radioactivity. With his concept of the nuclear atom he lead to the exploration of nuclear physics.He created the space model. He won the Noble Prize for chemistry. -
Marie Sklodowska Curie
She discovered polonium and radium. She worked a lot with radioactivity trying to find other materials that have similar properties as uranium. She was the first women ever to win a Nobel prize and the only to win a Nobel prize in two different subjects. -
Frederick Soddy
He worked with Rutherford on the disintegration of radioactive elements. He was one of the first to confirm than an element can have a different atomic mass. While they are indistinguishable and inseparable chemically. -
Max Planck
He was the originator of quantum theory.This theory revolutionized our understanding of atomic and subatomic processes. -
Nagaoka
Postulated a "Saturnian" model of the atom with flat rings of electrons revolving around a positively charged particles. -
Richard Abegg
He figured out the out electron clouds can hold eight electrons. He helped our understanding of valence which is the capacity of an atom to combine with another atom. -
Albert Einstein
He came up with the equation E=mc2. He also came up with the theory of relativity. He helped us have an understanding of time and space. He also worked and helped create the atomic bomb which is the splitting of an atom. -
Hans Geiger
He built the first version of his particle counter and used it and other radiation detectors to discover that the alpha particle is a helium atom. He helped Rutherford's correct proposal that in an atom the nucleus takes up a small amount of volume. -
R.A. Millikan
He began a series of experiments to figure out the charge of a single electron. His water experiment was not accurate enough to be convincing. But then he did an oil drop experiment and his results were more accurate. -
H.G.J. Moseley
He worked withe beta radiation in radium. He found a relationship between the frequencies of corresponding line is the X-ray spectra. The frequencies are proportional to the squares of whole numbers that are equal to the atomic number plus a constant. Which is known as Moseley's Law. -
Francis Aston
He studied the creation of X-rays by the flow of current through a gas filled tube. He thought he had discovered a new element which he called "meta-neon." -
Niels Bohr
The first scientist to apply the quantum concept to the atom. The quantum concept restricts the energy of a system to certain discrete values. With his research he applied the knowledge to the atoms molecular structure and created a new model. The model shows and electron cloud and that the electrons are 2,8, and continuing with 8 being the max of any section. -
Werner Heisenberg
He discovered a way to formulate quantum mechanics in terms of matrices. He helped the first nuclear reactor in West Germany. He published his uncertainty principle. Which states you cannot precisely state the velocity and a position of an object. -
Cockcroft / Walton
They created a generator together. The principle of their generator is that the voltage is doubled each time. It converts AC or low level DC to high voltage level DC -
Erwin Schrodinger
He made major contributions to the wave theory. He believed that light did not move in rays but in waves. He had the partial differential equation that is the basic equation of quantum mechanics . -
James Chadwick
His biggest discovery is that he discovered the neutron. He interpreted that radiation as being composed of particles of mass particles of mass approximately that of the proton but without electrical charge. -
Enrico Fermi
He did the first controlled chain reaction releasing energy from the atoms nucleus.
