Atomic Theory Timeline
Category: History
Updated: 10 months ago
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Created byJordan Lee
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Aristotle's Discovery- Although the date is approximate, Aristotle concluded in his Metaphysics book that all things are made up of form and matter which can only be changed with growth, decay, or motion. Objects are in turn composed of the five elements he believed existed: fire, water, earth, air, and aether.Description of discovery/contribution to atomic theory
argued that the four elements were not composed of atoms but were continuous forms of matter.Approximate date of discovery and description-the Greek philosopher Democritus introduced the idea of the atom as the basic building block matter. Democritus thought that atoms are tiny, uncuttable, solid particles that are surrounded by empty space and constantly moving at random.Contribution to the atomic theory- named the building blocks of matter atomosDate of Discovery-Dalton's experiments on gases led to his discovery that the total pressure of a mixture of gases amounted to the sum of the partial pressures that each individual gas exerted while occupying the same space. In 1803 this scientific principle officially came to be known as Dalton's Law of Partial Pressures.Contribution to the atomic theory-based on the concept that each element consists of its own unique brand of indivisible atom;Date of Discovery- Dmitri Mendeleev identified a general theory underlying all elements on 1 March 1869. It came to him in a dream, Dmitri Mendeleev told a friend. He hadn't slept for three days worrying how to classify the elements.Contribution to the atomic theory-developed the periodic classification of the elements.J.J. Thomson made his discovery-all atoms contain tiny negatively charged subatomic particles or electrons. Thomson proposed the plum pudding model of the atom, which had negatively-charged electrons embedded within a positively-charged "soup."date of discovery-In 1911, he theorized that atoms have their charge concentrated in a very small nucleus. This was done through his discovery and interpretation of Rutherford scattering during the gold foil experiment performed by Hans Geiger and Ernest Marsden, resulting in his conception of the Rutherford model of the atom.contribution to atomic theory- found that the atom is mostly empty space, with nearly all of its mass concentrated in a tiny central nucleus.Periods
AristotleDemocritus Birth and DeathJohn Dalton Birth and Death DateDmitri Mendeleev Birth and Death DateJ.J Thomson Birth and Death DateErnest Rutherford Birth Date and DeathHenry Moseley Birth Date and Death
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