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Jan 1, 1000
Democritus and the Ancient Greeks and Indian Philosophers before 1000 AD
Powers of Ten gives a basic understanding of atomic sizeCaptain PlanetAtoms are small particles that make up substances. Their characteristics contribute to the characteristics of objects in the world. The ideas of basic elements such as earth, water, fire, and air are considered to give their characteristics to matter. -
Dalton publishes A New System of Chemical Philosophy
Dalton's description of elements
John Dalton claims that every element has its own type of atom, atoms are indivisible, indestructable, and combine to form compounds. -
Thompson discovers electrons
He makes the Plum Pudding Model. Negative electons are embedded in a positive mass. -
Rutherford and the Gold Foil Experiement
A brief interactive description The dense nucleus is discovered by shooting alpha particles at a thin piece of gold foil. Most of the particles passed through, but a few were reflected from the center. The particles would only reflect off of a dense mass. -
Bohr Model
Niels Bohr uses Quantum Theory to show that electrons are located at specific energy levels. The Bohr Model is commonly used to visualize atomic structure. -
James Chadwick and the Neutron
Chadwick uses data that shows a radiation stronger than electromagnetic radiation and is neutrally charged to provide evidence for the neutron. -
Present Day: Electron Cloud Model
After the validity of the Bohr Model was disproved, Quantum Theory helped to show that electrons were more concentrated in specific areas around the nucleus. The areas were predictable but not with 100 percent confidence.
