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332
332 BC- Aristotle
Aristotle believed that all elements were made of fire, water, air, and earth. -
460
460 BC- Democritus
Democritus wondered what would happen if you began to to break matter apart and keep breaking it until it couldn't be broken anymore. He decided to call these basic particles of matter atoms. -
Lavoisier
He discovered that mass is conserved in a chemical reaction, meaning that the resulting material of the chemical reaction has the same mass as the starting material. -
Dalton
Dalton said that all elements are made of atoms. All atoms that make up the element have the same mass. -
Avogadro
This man discovered that equal volumes of all gases at the same temperature and pressure contain equal numbers of molecules. -
Berzelius
He made a table of atomic weights which included 43 elements. -
Mendeleev
Mendeleev grouped the elements into 7 different groups and found out that the properties of these elements were functions of their atomic weights. This was called the Periodic Law and was arranged into what we now know as the Periodic Table of Elements. -
Becquerel
Bercquerel discovered that chemicals decomposed after being exposed to x-rays. Alongisde that, the chemicals give off rays as well. -
Thomson
Thomson discovered the electron while experimenting with cathode-ray tube. Also, in 1904, he discovered that the model of the atom was spherical with elctrons surrounding it on the outside. He is credited for the Plum Pudding Model. -
Curie
Marie Curie discovered the decaying process of radioactivity. She discovered this using the elements of uranium and thorium. -
Rutherford
Rutherford studied radiations from uranium and thorium. He named these emmitions alpha and beta. He is also credited for performing the gold foil experiment, in which he emmitted rays through a thin, gold foil. -
Planck
Planck is credited for describing hot glowing matter using quanta. -
Millikan
Millikan discovered the charge of an electron using an oil apparatus experiment. -
Moseley
H.G.J. Moseley found out that the atomic number of an element is equal to the number of protons in the nucleus. He used x-ray tubes to figure out the charge of atoms. Because of this, the Periodic Table was reorganized as well. -
Bohr
Bohr developed a way to explain atomic structure using the Periodic Table of Elements. This atomic model features orbitals of electrons and a nucleus of protons and neutrons. This is called a Bohr diagram. -
Heisenberg
Heisenberg is credited for the Proposed Principle of Indeterminancy. It means that you can't know the position and velocity of a particle. -
Schrodinger
You may know this man because of his cat. Schrodinger thought of electrons as a cloud. He also introduced wave mechanics. If you really want to know, his cat is so famous because it illustrates a quantum theory superstition. -
Meitner
She helped discover nuclear fission. -
Chadwick
Chadwick used the alpha particles discovered by Rutherford to discover the neutron.
