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400
Democritus
About 400 B.C., this Greek philosopher suggested there was a such thing as matter and eventually the matter will be broken down into a piece that can no longer be broken down. He called these pieces atoms and the properties of these also determined the properties of the object it made up. -
Robert Boyle
He is known as the "father of chemisty". He developed a definition of an element. He generally said that it was any substance (or body) that can not be broken into two or more substances is an element. -
Antoine Lavoisier
Antoine was a French chemist known his many experiments. He came up with the Law of Conservation of Mass, which states that matter cannot be made or destroyed. He also stated that matter can be rearranged, but it never disappears. -
John Dalton
Dalton was born in England and developed an interest for science through meteorology Dalton's atomic theory said things like:
-Matter is composed of atoms.
-You can’t make or destroy atoms.
-Atoms of the same element are the same.
-Chemical reactions happen when atoms are rearranged.
-Compounds are formed with atoms of different elements.
-Atoms can be differentiated by their weight. -
Dmitri Mendeleev
Mendeleev is was born in Siberia and became a chemist. He is known for his creation of the first periodic table of chemical elements. He rearranged the elements by chemical properties and not by their atomic weights. He founded 3 elements in his lifetime. He also came up with a theory about the missing elements -
Eugen Goldstein
Goldstein was a German physicist who helped to discover the proton and he also discovered canal rays. Negative charged particles moved toward the positive end, but some were going toward the negative end which are canal rays. -
J.J. Thomson
He was a British physicist who discovered the electron. His model of the atom showed a sphere with positive matter which electrons are positioned by electrostatic forces. Electrostatic forces are how the electrons stay positioned. -
Max Planck
He was a German physicist best known as the originator of the quantum theory of energy. The quantum theory is the theory of matter and explains the nature and behavior of matter and energy on the atomic and subatomic level. -
Robert Millikan
He was an American physicist who worked on the elementary charge of electricity and on the photoelectric effect. He also determined that charge carried by electrons. Millikan is also a Nobel Peace Prize winner. -
Ernest Rutherford
He describes the atom as having a central, postive nucleus surrounded by negative orbiting electrons. The mass of the atom was contained in the small nucleus, and the rest of the atom was pretty much empty space. He was known for his famous gold foil experiment. Rutherford also won a Nobel Peace Prize. -
Niels Bohr
Niels was born in Denmark and became the first one to discover that electrons travel in separate circular orbits around the nucleus of an atom. He also said that the number of electrons in the outer orbit determines the properties of an element. Bohr also made contributions to the quantum theory. He won a Nobel Peace Prize too. -
Erwin Schrodinger
This Austrian physicist took the Bohr atom model one step further. He used mathmatical equations to describe the likelihood of finding an electron in a certain position. It was known as the quantum mechanical model of the atom. It didn't define the exact path of an electron, but it predicted the odds of the location of the electron. -
James Chadwick
Chadwick was born in England and studied under Rutherford. He is known for proving the existence of neurons and won a Noblel Peace Prize too. His discovery helped in the creation of the atomic bomb.
