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400 BCE
Democritus
Democritus lived from about 460 BC - 370 BC. Around 400 BC, he speculated that the atom is the building block of all things. As well as the idea that they are tiny, uncuttable particles. -
395 BCE
World Event: The Corinthian War Begins
About 5 years after Democritus' discovery the Corinthian War begins between Athens, Thebes, Corinth, and Argos against Sparta. -
World Event: Louisiana Purchase
The Lousiana Purchase occured the same year as Jack Daltons discovery -
John Dalton: Marble Model
John Dalton (1766-1884) is considered "The Father of Modern Chemistry". He discovered that elements reacted in a whole-number ratio. He came up with the "marble" model, a simple sphere representing an atom. -
Michael Faraday
Michael Faraday (1791-1867) introduced the idea that atoms could be interacted with through forces of electricity and magnetism. -
Eugene Goldstein
Eugene Goldstein (1850-1930) discovered canal rays (positively charged particles) contributing to the understanding that atoms contain subatomic particles. -
JJ Thomson: Plum Pudding Model
JJ Thomson (1856-1940) discovered the electron and proposed a "plum pudding" model in 1887 where electrons are embedded in a positively charged sphere. -
World Event: The Eiffel Tower Opens
The Eiffel Tower first opened in 1889, two years after the plum pudding model was introduced. -
Robert Millikan
Robert Millikan (1868-1953) discovered that electrons all carry the same amount of a negative charge -
Ernest Rutherford: Nuclear Model
Ernest Rutherford (1871-1937) Discovered the nucleus of an atom with his famous gold foil experiment. He created the "Nuclear model" with a dense positively charged core with electrons orbiting it. -
Neils Bohr: Solar System Model
Neils Bohr (1885-1962) proposed a model of the atom in which electrons orbit the nucleus of ana tom in a planetary-like mtion. -
WWI Begins
WWI begins just a year after Bohr's discovery -
World History: Treaty of Versaille Signed
In 1919 the Treaty ofVersaille is signed, formally ending WWI -
Edwin Shroedinger: Electron Cloud Model
Edwin Shroedinger (1887-1961) proposed that electrons travel in waves in a designated space. Electrons = matter waves. -
Werner Heisenburg
Werner Heisenberg (1901-1976) discovered there's a limit to the accuracy of the data collected when trying to determine the physical properties of an electron such as location speed/position momentum. -
James Chadwick: Electron Cloud Model with Neutrons
James Chadwick (1891-1974) discovered that there was another subatomic particle within the nucleus of an atom. This was the neutron, a subatomic particle void of charge. -
World Event: The Start of WW2
About 7 years after Chadwicks discoveries, WW2 started when Germany declared war on Poland.