-
500 BCE
Democritus
He believed that all mater including space and time, were made up of atoms. He never took his belifs further and experiments he simply went off of what he thought. Thanks to Lucretius. -
499 BCE
Heraclitus
Was known for believing everything was made up of fire. -
450 BCE
Aristotle
He never believed in the atomic theory so proceeded to teach it differently. He believed that everything on earth was not made of atoms rather of four substances, earth, fire, water, and air. He believed that substances on earth were created by these four elements of matter. -
Dalton
Also belived that all matter was created by atoms, but he believed they could be rearranged. He experimented by combining two atoms and seeing thatb the mass and properties were identical. -
J.J Thomson
He was the one who discovered the electron. He decided to support his claim by experimenting. He studied the nature of the electricity in a object called a cathode ray tube. Which was powered by a vacuum and could determine what type of substance it was. Which he also refereed to as "plum" or "plum pudding" -
J.J Thomson's Experiment
-
Rutherford
He discovered that atoms have a small nucleus. Surrounded by a large empty space circled by electrons. He stated that the nucleus held the most mass. He believed that atoms went directly through. -
Rutherford's Experiment
-
Bohr's Experiment
-
Bohr
Bohr believed that in the atomic structure consisted a proton, nucleus, and one moving electron in a circular motion around it. He believed that because of this when colors of light were released it would not simply be one color rather a rainbow of colors. So when electricity goes threw the tube electrons gain energy and when it drops back down the electrons loose that energy. -
Schrodinger
He believed that electrons do not orbit rather float in a space. He said that there was no evidence as to where the electrons were located, but they were there. He believed that by knowing the energy level of an electron you could plug it in to find out exactly where it is located. -
Chadwick
He went off of Schrodinger's theory and introduced sub-energy levels. He believed that an atom was composed of a positively charged nucleus with negatively charged electrons on the outside. He believed that the nucleus held all of the mass. To prove his theory he used different metals and hit them with alpha particles. By doing so this introduced a new particle called the neutron.
