-
400
Democritus
Democritus wondered in 400 BC if there was a possible smallest piece of matter. He womdered if you kept breaking matter, it would have to stop at the smallest piece. So, his theoy was that all matter was made up of indivisible particles, which he then called atoms. -
Law of Conservation of Mass
The Law of Consetvation of mass was established by Antoine Lavoisier in 1789. This law of states that matter can niether be created or destroyed. It also means that the the amount of mass always stays the same. Adam Lavoisier came discovered a great law and he became one of the founders of modern chemistry. -
Law of Definite Proportions
The law of definite proportions was created by Proust in 1795. His law ststes that elements can form compounds in very small amounts.This law and the the law of conservation of mass wold become Dalton's first atomic theory. -
Spherical Model
The spherical model was created by Jon Dalton, a teacher, in 1802.His mode; shows that all atoms of an element ar very small and indivisible solids. -
First Atomic Theory- Dalton
The law of conservation of mass, and the law of definite proportions, were brought together to form Dalton's atomic theory. This was the first atomic theory and it stated that everything is made up of tiny indivisble atoms. They have differnt atoms for differnt elements and the same atoms for the same element. All of these were based on Dalton's experiments. -
Quantum mechanical model
This was devised by Einstien in 1902. His theory was that radiation is also quantized. Radiation has properties of bothe waves and a stream of particles. -
Plum Pudding Model
This was created in 1904 by JJ thompson, after he had discovered the electron while doing the Cathode Ray tube experiment. -
The Gold Foil Experiment
The gold foil experiment was an experiment done by chemist Ernest Rutherford. The goal of his experiment was to shoot alpha particles through a thin gold piece of foil and to see what happened. The results were that most of the alpha particles went straight through the foil with no deflection. A small portion of other particles only deflected slightly. With this, Rutherford determined that atoms have all of their mass in a very concetrated center, the nucleus. -
Nuclear model
This was a model by ERnest Rutherford that was proposed in 1911. It was made to show that all atoms have a very small, dense core that contained protons and nuetrons. This was the nucleus. -
Bohr atomic model
The Bohr atomic model was created to show the properties of atomic electrons.It was created by Niels Bohr in 1913 and it also shows the amount of electrons in that certain atom. -
Quantum Theory
Quantum theory was devised by chemist Niels Bhor in 1920. This theory accurately describes the universe at a very small scale. This gave modern chemistry a new way to understand why, and how elements make bonds, which shows a new understanding of atomic structure. -
Theory of Quantum Physics
This was a theory created by Heisenberg in 1925. His theory was based on the radiation that was emmitted by an atom. It even specifies different ways to describe the universe. -
The Uncertainty Principle
The uncertainty princible was established by Heisenberg in 1927. It states that it is impossible to measure the exact location of an atom with exact precision. -
Chadwick discovers the nuetron
Chadwick was an English scientist who was a lab assistant to Ernest Rutherford after WWl. While working there, he performed an experiment and discovered the nuetron. Chadwick put a piece of beryllium in a vacuum chamber with some polonium. The polonium shot out alpha rays, which hit the beryllium. When hit, the beryllium created the neutral rays. -
Cathode Ray Tube Experiment
This experiment was a major dicovery in Atomic Structure. This experiment by JJ Thompson was the one that made Thompson discover the electron. The cathode ray tube experiment started when he placed cathode tubes in electric and magnetic fields. He saw that the cathode rays bent to one side, so he knew that there was an other subatomic particle in the atom. This was the electon.
