September 30, 2021
For educational institutions
"History of the Atom" - Physical Science - Shahroze M.
This timeline is a basic synopsis/guide to the history of an atom.
⟶ Updated 17 Oct 2018 ⟶
List of edits
How to view the timeline:
1) Press the full-screen button. It's below the '+' for zoom in and '-' for zoom out.
2) Drag around the screen to view the whole timeline, one way to do this is by pressing the middle mouse button. Another, not recommended, is to press the left mouse button.
14 Oct 2018
Democritus' Discovery 400 BC - 301 BC Democritus, a philosopher from the time period of the fourth century BC, discovered how substances can be cut till they're uncuttable.
Dalton's Discovery 1805 Dalton explored the foundation of the atomic theory, this discovery is beginning of our use today. He provided the theory of the following: 1) Elements are made of small particles called atoms 2)Atoms of the same elements are the same; atoms of different elements are different 3) Atoms can't be created or destroyed 4) Atoms of different elements combine in simple whole ratios to form compounds 5) In chemical reactions, atoms are combined, separated, or changed.
J.J. Thompson's Discovery 1897 J.J. Thompson experienced with the materials or powers inside of an atom. He bent a cathode tube and noticed it would bend towards a positive charge and away from a negative charge in part of the experiment. He figured that atoms have negative particles inside of them called electrons.
Ernest Rutherford's Discovery 1911 Ernest Rutherford added on to Dalton's and Thompson's discovery. He explained that an atom's also made of a tiny positive nucleus in its center. He believed that if atoms only held electrons it would pass through a gold foil sheet. However, some bounced off, hinting that there is a positive factor to the atom.
Neils Bohr's Discovery 1913 Neils Bohr pull was that electrons have set energy levels but can jump at higher or lower intervals. He discovered this in 1913, adding onto the previous work by other scientists. Bohr believed that electrons release energy in a form of light. His model only works for Hydrogen.
William Heisenberg's Discovery 1926 - Present William Heisenberg figured that knowing the position of an electron or its speed are not definite. One option is only available in this theory. He supported an Electron Cloud Model that predicts an area where an electron could be. It's known as the Quantum Mechanical Model.
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