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460 BCE
Democritus
He believed that everything is composed of atoms, which are invisible. He discovered that between atoms, there is empty space.
He also thought that atoms have always been, and always will be, in motion. He was able to determine that there are an infinite number of atoms, and kinds of atoms, which differ in shape, and size. He traveled around the world but lived mostly in Greece
460 BCE- 370 BC -
384 BCE
Aristotle
Aristotle was an ancient Greek philosopher and scientist (384–322 BC) Along with Plato, Aristotle is considered the "Father of Western Philosophy", His writings cover many subjects – including physics, biology, zoology, metaphysics, logic, ethics, aesthetics, poetry, theatre, music, rhetoric, psychology, linguistics, economics, politics and government – and constitute the first comprehensive system of Western philosophy. He believed all concepts and knowledge were ultimately based on perception. -
Antoine Lavoisier
He was a French chemist who believed that matter couldn't be created or destroyed. Chemistry students today are still taught the conservation of mass as “Lavoisier’s law”. -
Joseph Louis Proust
Proust was a French scientist who came up with the Law of Definite Proportions. -
John Dalton
Dalton lived in England. He thought that atoms of different elements varied in size and mass. His main focus was to determine the relative masses of each different kind of atom.
Dalton’s atomic theory earned him the title “father of chemistry.” -
Billiard Ball Model
John Dalton proposed this model in the early 1800s. He envisioned atoms as solid, hard spheres so he made the model out of wooden pool balls. -
JJ Thomson
Thomson lived in England. He discovered the electron by trying to solve a question about cathode rays, which occur when an electric current is driven through a vessel that most of the air has been pumped out. Thomson was able to find that these rays were composed of particles. The rays seemed to be composed of the same particles, regardless of what kind of gas carried the electric discharge or what kinds of metals were used as conductors, so that's how he discovered electrons. -
Max Planck
Max Planck (April 1858 – 4 October 1947) was a German theoretical physicist who discovered energy. Planck made many contributions to theoretical physics, but his fame as a physicist rests primarily on his role as the originator of quantum theory, which revolutionized human understanding of atomic and subatomic processes. -
Albert Einstein
Albert Einstein was a German physicist (14 March 1879 – 18 April 1955) who developed the “world's famous equation”, E=mc2. He received the 1921 Nobel Prize in Physics by a pivotal step in the development of quantum theory. He continued to deal with problems of statistical mechanics and quantum theory, which led to his explanations of particle theory and the motion of molecules. He also investigated the thermal properties of light which laid the foundation of the photon theory of light. -
James Chadwick
Sir James Chadwick, (20 October 1891 – 24 July 1974) was a British physicist who discovered the neutron in 1932. In 1941 he also wrote the final draft of the MAUD Report, which inspired the U.S. government to begin serious atomic bomb research efforts. -
Werner Heisenberg
Heisenberg was a German physicist who worked on developing a theory about a nucleus in the atom. He also came up with the Principle of Uncertainty. -
Plum Pudding Model
This was proposed by JJ Thomson, he thought that the atom consisted of more than one fundamental unit, this is how electrons were discovered. He found out that atoms had both a positive and negative charge. -
Robert Oppenheimer
He lived in the United States. He is known as “the father of the atomic bomb”, because of his work as an American nuclear physicist and director of the Los Alamos Laboratory (Manhattan Project). -
Rutherford Atomic model
The Rutherford Atomic Model was created in 1909 by Ernest Rutherford. The Rutherford Atomic Model explains and describes an atom. He explains it as positive protons and neutrons (the nucleus) is being surrounded by negative electrons. -
Bohr Model
This model was proposed by Niels Bohr. He discovered that atoms have a positively charged nucleus that is surrounded by electrons moving in a circular orbit around the nucleus. He also thought that the number of the positive charge in the nucleus is the same number of electrons. -
The Wave Model
The Wave model was designed by Erwin Schrödinger in 1926. A wave model is a theoretical concept comparing a phenomenon of any type to any part of a physical wave. -
The Quantum Mechanical Model
The quantum mechanical model was made by Erwin Schrödinger in 1926. Schrödinger took the Bohr atom model and used mathematical equations to describe finding an electron in a certain position. -
Lucas Model
Lucas's model is a physical representation of where electrons are located throughout atoms. It also shows the structure of the nucleus.
