-
400
Democritus (400 B.C.)
He said that everything is made of atoms and the atoms, which are invisible and indestructible.He found that compounds are formed by different types of atoms. Democritus discovered chemical reactions just rearrange atoms.
https://the-history-of-the-atom.wikispaces.com/Democritus -
Antoine-Laurent de Lavoisier
He helped discover the basic elements.He suggested the Oxygen is present in combustion. He wrote a book called "Elements of Chemistry." He came u with the Law of Conservation of mass, which stated that the mass of each element will be the same after the reaction that is was before the reaction.
http://comenius.susqu.edu/hons/250/scientists/lavoisier.htm -
John Dalton
. Elements are made of atoms. He stated that atoms are indestructible, solid, invisible, homogenous matter.
He said all atoms of the same element are identical and they have the same mass. He also said that one element has different atoms than another element.
https://sites.google.com/a/maricopa.edu/joaquin-sandoval/home/chemistry -
Sir William Crookes
He investigated cathode rays throught the Crookes tube. He also investigated plasma.
https://introtochem.wordpress.com/modules/module-07-2/73-2/ -
Sir Joseph John Thomson
He identified the electron. Crookes cathodre rays helped him to figure this out. He was eating plum pudding one night and he had rasins in it. He used that as a model which represented the electrons in an atom.
http://www.britannica.com/science/Thomson-atomic-model -
Ernest Rutherford
He came up with the concept of half life. He dealt a lot with radioactivity. He conducted an experiment where he shot alpha particles though a piece of gold foil. Some particles did not go through due to it hitting the nucleus of an atom.
http://www.daviddarling.info/encyclopedia/R/Rutherfords_experiment_and_atomic_model.html -
Niels Bohr
He came up with the idea that atoms had empty space and a positivly charged center. He suggested that atoms had electrons in circular orbitals around the nucleus of the atoms. Bohr had the idea that electrons travel outside of the nucleus in orbitals. The farther out the electron is, the more excited it is and the closer to the atom is getting closer to ground state. He said that wavelengths(colors) come from the differing levels of energy.
https://en.wikipedia.org/wiki/Bohr_model -
Erwin Schrodinger
He said that the electrons do not have to be where they are supposed to be. He said that all the models before were just a probibility of where the electron might be. He created a paradox with a cat, which was alive and dead at the same time.
https://www.haikudeck.com/democritus-art-and-design-presentation-fUSsoW4H8B#slide20 -
James Chadwick
He discovered that a neutron is in the nucleus without a charge. He said that the neutrons make up about half the mass of an atom. He discovered that the number of protons make up the atomic number.
http://jameschadwickatomictheory.weebly.com/
