History+of+Atoms

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== = = = = We are going to take a look at the "History of the Atom"First, we're going to introduce some people and get to know them!

Democritus

[|Democritus]

**Questions:** **1) What did Democritus believe about matter?** **2) What word do we get from his description?** **3) Where and when did he do this?** **4) Did many other philosophers agree with him?**  II. John Dalton [|Dalton]

[|More on Dalton]

came up with the model of the solid sphere

**Questions continued:** 5) When did John Dalton come up with the idea of an atomic theory? 6) In his book, A New System of Chemical Philosophy, how did he propose to identify elements? <span style="color: #665252; display: block; font-family: Georgia,serif; text-align: center;">7) What were some of John Dalton's basic ideas about matter? <span style="color: #665252; display: block; font-family: Georgia,serif; text-align: center;">8) John Dalton is known as the Father of ... <span style="color: #4d4c4c; display: block; font-family: 'Palatino Linotype','Book Antiqua',Palatino,serif; text-align: center;">

** Questions continued: ** 9) What was so special about this glass tube Crookes used? (Describe the distinguishing features of the tube) 10) What were the streams of particles called according to Crookes and why? (look on page 10 and 11 of your textbook)

<span style="color: #4d4c4c; display: block; font-family: 'Palatino Linotype','Book Antiqua',Palatino,serif; text-align: center;">--- ** Questions continued: ** 11) Discribe or Draw in WordArt Thomson's Atomic Model (look on page 12 of your textbook)

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**Questions continued:** 12) Explain Rutherford's experiment. (look on page 13 of your textbook)

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<span style="color: #800080; display: block; font-family: 'Arial Black',Gadget,sans-serif; font-size: 130%; text-align: center;">Actually today’s atomic model is based on the principles of __wave____mechanics__.According to the theory of wave mechanics, electrons __do not move__ about an atom in a __definite path,__ like the planets around the sun. <span style="color: #800000; display: block; font-family: 'Arial Black',Gadget,sans-serif; font-size: 130%; text-align: center; vertical-align: baseline;">lIn fact, it is __impossible__ to determine the exact location of an electron. The __probable__ location of an electron is based on how much __energy__ the electron has.This is seen in the electron cloud model.

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** Keys Parts of our Lecture to Remember: ** 1. An __atom__ is the basic unit of an element 2. //Matter// is anything that has "Mass" and "Takes Up Space" 3. Mass is different from Weight 4. A //theory// is an idea that can't be proved at this time 5. Elements have been viewed and categorized differently﻿ in history 6. Democritus believed matter was made up of small particles or atoms 7. John Dalton proposed several ideas about matter in relation to the atom 8. William Crookes developed the "Glass Tube Experiment" which showed a beam of charged particles 9. JJ Thomson used Crookes experiment to show that the beam of particles was not light 10. Thomson discovered that negatively charged particles (electrons) are attracted to the positive charged part in the Glass Tube 11. Rutherford discovered that the positive charged alpha particles repelled the positive protons of the Gold foil atom