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427 BCE
Plato
They wrote a book "A New System of Chemical Philosophy" which put in pictures of how elements combine to form compounds. -
400 BCE
The Alchemist
They believed they could turn lead into gold. -
400 BCE
Democritus
They were the first to believe that material was made of smaller things and any type of atomic theory. -
322 BCE
Aristotle
They discovered that all ordinary substances are made of earth, wind, fire, and water. Also, that all matter is constructed of atoms. -
300 BCE
Aristotle
They recognized that material things are made of multiple substances and that the four elements earth, wind, and fire adn water contribute to making all substances. -
Robert Boyle
They believed that if the volume of gas is decreased then then the pressure majorly increases. Which led him to believe that all gases are made of tiny particles. -
Lavoisier
Lavoisier created the modern atomic model along with others. He also created the Law of Conservation -
John Dalton
They believed that elemets consist of atoms and all atoms of a element are identical. They also believed that atoms cannot be created or destroyed. -
Dimitri Mendeleev
They believed that all of the elements were arranged in order of increasing atomic mass. -
Photoelectric Effect
The Photoelectric Effect was discovered by Einstein. This effect is the emission of electrons from the surface of metals when any radiation hits the metal on its surface such as light. -
J.J. Thomson
They experimented with cathode ray tubes showed that all atoms contain tiny negatively charged subatomic particles or electrons. They also introduced the "Plum Pudding" model. -
The Curies
They believed that they discovered 2 radioactive elements called Polonium and radium when Marie Curie experimented on uranium rays. They also believed that the rays where from the elements atomic structure. -
Planck's Quantum Theory of Light
They believed that the energy of light is proportional to the frequency. -
Planck's Quantum Theory of Light
They believed that the energy of light is proportional to frequency. -
Albert Einstein
They believed that atoms existed and that any liquid is made up of molecules. He also calculated the size of atoms and molecules. -
Robert Millikan
They discovered the determination of the charge of an electron with oil drops. The oil drop experiment contained of oil drops in the middle of 2 electrically charged plates when there was no charge the oil dropped at a constant rate. -
Earnest Rutherford
He did famous Gold-Foil Experiment -
Neils Bohr
They believed that the electron was only able to to occupy certain orbits around the nucleus. That atomic model was the first to use the quantum theory. -
Henry G. J. Moseley
They believed that the atomic number is the number of positive charges in the atomic nucleus. He also believed that there were then 3 unknown elements with the numbers 43,61, and 75 -
Schrodinger Equation
This equation is believed to solve to calculate the chances of an electron being in any given space in the nucleus. Also known as the electron cloud. -
Werner Heisenberg
They discovered the uncertainty principle which states that a particle's position and momentum cannot both be known exactly. He also won a noble prize for that. -
James Chadwick
They believed they discovered neutrons. They differed from alpha rays because they repelled considerable electrical forces that are in the nucleus of many heavy atoms. A neutron can then penetrate and split the nuclei of most elements.
