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Isaac Newton
Isaac Newton believed that the entire universe was made up of small tiny particles called atoms that were constantly in motion. He also realized in his researching that heat is by molecular motion. -
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Discovery of the Atom
Descriptions and contributions of 15 scientists that helped discover the atomic theory. -
John Dalton
He proposed that all elements were made up of atoms that had identical masses and that compounds were more than one elements combined. He calculated atomic weights based off of the percentage composition of compounds. Dalton also knew that the particles in gases had different volumes which explains why gases in the atmosphere didn't just split apart but were kept in motion. -
Sir William Crookes
Constructed experiments with cathode rays to prove that cathode tubes have negative charges. He experimented with these cathode rays and proved they travel in straight lines and conduct heal on some objects. He tried to propose a "fourth state of matter" called radiant matter but was proven wrong. -
George Stoney
He tried to calculate the number of molecules in a certain amount of gas. His method for this was later proven wrong, but he also tried to give reasons on why helium and hydrogen escaped from earths atmosphere based off of our moon not having an atmosphere. -
JJ Thomson
He proposed that the atom is a sphere of positive matter. He also said that the electrons were in their place based off of electrostatic forces. He tried to estimate the number of electrons in the atom but could never be successful. -
Max Planck
He's most famously known for his discovery of the quantum theory. This is the understanding of discrete units of energy for example light. Another word for this is photons. All of his ovservations were submicrosopic. -
Frederick Soddy
Soddy came up with the term "Isotope." Which is the same element containing different masses but the same chemically. He also printed books that helped in the research of radioactivity. -
R.A. Millikan
Conducted the oil drop expirement which allowed him to figure out the charge and mass of an electron. He was also a very successful author which helped contribute to the atomic theory. -
Ernest Rutherford
He worked with many famous scientists during this time which all gave many contributions. Starting with transmission of radio waves, radioactive decay, and discovering the neutron. -
Neils Bohr
He said that the electrons move in a distinct way, and that energy is transferred in certain quantities. Finally, he said that light is emitted when jumping from one orbit to another with a lower amount of energy. -
Louis De Broglie
Figured out that electrons had a dual nature which is the same to the nature of both particles and waves. This is called particle/wave duality. -
Werner Heisenberg
He is well known for his theory of quantum mechanics. He majorly contributed to the discovery of allotropic forms of hydrogen. In quantum mechanics he said you cannot determine both the velocity and position of an atom at the same time. -
Paul Dirac
Came up with a strong theory that a positive particle much like that of the negative particle electrons existed. This was later proven to be correct. Also famous for his wave equation. -
James Chadwick
Discovered the neutron and that its mass was relatively close to that of a proton by using alpha particles. -
Enrico Fermi
Made the first man-made nuclear reactor which releases energy from the atoms nucleus.
