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460 BCE
The First Event
Democritus is born in Greece -
400 BCE
Democritus' Atomic Theory
Democritus suggests that all matter is made up of small indestructible units he called "atomos"- which roughly translates "not cut" or "uncuttable". Unfortunately, his theory was overshadowed by Aristotle's theory, in which all matter is made up of the four elements (Fire, Earth, Water, Air). -
Dalton's take on the Atomic Theory
Many centuries after Democritus, John Dalton proposed the same atomic theory. Dalton suggested that the atom was a small indivisible thing that made up all matter. At the time this model was created, there was no nucleus or electrons. Because of this, it was called the Billiard Ball Model. -
JJ Thomson Improves Dalton's model
In 1897, Thomson discovered electrons, causing many to realize that atoms are made up of particles smaller than what they had originally thought. Later in 1904, the "Plum Pudding" model is created. Thomson theorized that the negative electrons swim in a "soup" of positive charge. -
Earnest Rutherford's Model
After conducting several experiments, Rutherford concluded that atoms were actually a tiny and dense positively charged core- later called the nucleus- surrounded by negative electrons. As this model resembled a solar system, one could probably guess what it is often called. -
Hantaro Nagaoka's Saturnian Model
In 1903, Nagaoka suggested that the atom is a large positively charged sphere surrounded by hundreds of electrons, which looked like Saturn and it's rings. -
Niels Bohr and the Atomic Theory
Back in 1913, Niels Bohr suggested that electrons moved around the nucleus in prescribed orbits. When the electron jumped to an orbit with less energy, light was emitted. This discovery got him a Nobel prize in 1922. -
Werner Heisenburg
Heisenburg creates the Uncertainty Principle, which states that it is impossible to measure both the momentum and position of a particle simultaneously with high precision. -
Chadwick's Model
As part of an experiment, in 1932, James Chadwick blasted beryllium atoms with alpha particles. As a result, an unknown radiation was emitted. Chadwick suggested that this radiation was made up of particles that had a neutral charge and were as big as protons. And so, the neutron was found, making adequate models of atoms for other chemists. -
The Last Event
Higgs is awarded the Nobel peace prize
