1 / 13

Chemistry

Chemistry. 10/14 The History of the Atom. ChemSaver p 17. (400 B.C.) Democritus of Adbera (northern Greece) asserted that all material things are composed of extremely small irreducible particles called atoms .

rogan-goodman
Download Presentation

Chemistry

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Chemistry 10/14 The History of the Atom

  2. ChemSaver p 17 • (400 B.C.) Democritus of Adbera (northern Greece) asserted that all material things are composed of extremely small irreducible particles called atoms. • The atomic theory was roundly rejected by Aristotle, and, thus, by almost everybody else for the next two millennia.

  3. Democritus’ Atomic Model

  4. Dalton’s Atomic Theory (1808) John Dalton 1. All matter is composed of extremely small particles called atoms 2. Atoms of a given element are identical in size, mass, and other properties; atoms of different elements differ in size, mass, and other properties

  5. Dalton’s Atomic Theory Continued (1808) John Dalton 3. Atoms cannot be subdivided, created, or destroyed 4. Atoms of different elements combine in simple whole-number ratios to form chemical compounds 5. In chemical reactions, atoms are combined, separated, or rearranged

  6. Dalton’s Atomic Model

  7. Cathode Ray Experiment • What will the particles in the tube do when the current is turned on? • What evidence did this experiment provide that electrons are negatively charged? • How do you think this experiment would be different if more powerful magnets were used? Click here for demonstration

  8. Chem Saver page 17 • JJ Thomson • The Cathode ray tube experiment showed: • That atoms are divisible. • That negatively charged particles can be easily ejected from an atom. • Thomson developed the “plum pudding model” of the atom (chocolate chip cookie dough from my point of view!)

  9. JJ Thomson’s Atomic Model

  10. Rutherford’s Gold Foil Experiment • Why did most of the alpha particles pass through the gold foil undeflected? • Why were a few of the alpha particles deflected at wide angles when they passed through the gold foil? • Why did some alpha particles appear to bounce off the gold foil at very large angles, some even back toward their source? Click here for demonstration

  11. Chem Saver page 17 • Ernest Rutherford • Since some alpha particles “bounced” back Rutherford concluded: • Atoms are mostly empty space (99+%) • Atoms have a small, dense, and very positive nuclei • Most of the mass of an atom is in its nucleus

  12. Rutherford’s Atomic Model

  13. The size of a nucleus to the electron cloud of an atom is similar to the size of one blade of turf in reliant stadium

More Related