-
500 BCE
The Alchemists
The Alchemists created the atomic theory. This theory states that all matter is composed of particles called atoms. -
492 BCE
Democritus
Democritus and his mentor Leucippus discovered the first atom theory. They believed that everything is made of tiny things that never get deleted, they can only be moved or changed. -
427 BCE
Plato
Plato introduced the atomic theory in which ideal geometric forms serve as atoms. According to which atoms broke down mathematically into triangles, such that the form elements had shapes. -
332 BCE
Aristotle
Aristotle discovered that there were elements related to atoms. These elements were air, water, earth, and fire. -
Robert Boyle
Robert Boyle discovered that atoms must exist based on the relationship between pressure and volume of gas. -
Lavoisier
Lavoisier found that the total mass of products and reactants in a chemical reactions is always the same. This led to the theory of the law of conservation of mass. -
Billiard Ball Model
Created by John Dalton. -
John Dalton
John Dalton was the first scientist to explain the behavior of atoms in terms of the measurement of weight. -
Dmitri Mendeleev
Dmitri Mendeleev created the first periodic table of elements. He concluded that there were still more elements to find and added to the table. -
J.J. Thomson
J.J. Thomson discovered the electron. He is known for the Thomson atomic theory. -
The Curies
The curies discovered a ew element, which would prove that the atoms of one element at least were not indivisible. -
Plum Pudding Model
Created by J.J. Thomson. -
Robert Millikan
Robert Millikan created a better method for measuring an electric charge. -
Ernest Rutherford
Ernest Rutherford re-constructed the nuclear structure of the atom. He also discovered alpha and beta rays and proposed the laws of radioactive decay. -
Solar System Model
created by Neils Bohr. -
Niels Bohr
Niels Bohr created the Atomic Model. The Bohr model shows the atom as a small, positively charged nucleus surrounded by orbiting electrons. -
Henry G.J. Mosely
He created the Mosely law. Moseley’s law is an empirical law concerning the characteristic x-rays that are emitted by atoms. -
Electron Cloud Model
Created by Werner Heisenberg. -
Werner Heisenberg
Werner Heisenberg discovered the uncertainty principle. This states that it is impossible to specify the precise position and momentum of a particle at the same time. -
Albert Einstein
Albert Einstein created the Manhattan Project. This was a research project funded by the U.S that led to the creation of the atomic bomb.
