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400 BCE
Democritus (400 B.C.)
He was a Greek philosopher who first mentioned the idea of atoms. He stated that if a substance was repeatedly divided, it would reach a point where it couldn't be divided anymore. This state would be called an "atom". Matter would be made up of these atoms. -
John Dalton (1808)
He was a teacher set in England who spent much of his free time examining chemical reactions. John Dalton contributed greatly to the Atomic Model, proposing the idea that atoms are gases that repel each other. He also argued that each atom is different. In 1808, he created the first model of an atom. -
J.J. Thomson (1897)
He discovered negatively charged particles called "electrons". Thomson also created the raisin bun model, which featured electrons in an atom full of a positive charge. It was because of him that Atom Physics is considered a modern science today. -
Ernest Rutherford (1911)
He was born in Scotland and studied at Canterbury College. Rutherford discovered that an atom is mostly empty, save for the dense nucleus. Here the particles collected. He also discovered the positively charged atoms in the nucleus, called protons. -
Niels Bohr (1913)
Bohr was born in Copenhagen and studied at the University of Copenhagen in 1903. He used Rutherford's data and model to discover that "electrons move around the nucleus in particular energy levels" (Development of the Atomic Model). Bohr also discovered that electrons closer to the nucleus have less energy, while those farther away had more. -
Erwin Schrodinger and Werner Heisenberg (Modern Atomic Model)
Born in Vienna, Austria and studied at the University of Vienna, Erwin contributed to the modern atomic model. He discovered that the hydrogen levels of an atom could be calculated using the Schrodinger equation. Heisenberg was born in Germany and received a Ph.D. at the University of Munich. He was awarded the Nobel Prize for creating quantum mechanics.
