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History of the Atom


Title: History of the Atom
Description: Honors Chemistry
October 9, 2020

Topic: Development of Atomic Structure (text pg 106 -111)

    Hoberman sphere (represents path of electrons around nucleus of atom)
        a marble placed on second base of the Houston Astrodome would be
        the approximate ratio of size of nucleus:  atom.
    Democritus (Greek) atomos = indivisible  [bowling ball model of atom]
        atom had NO protons, neutrons, electrons and was solid and indestructible

    Dalton (~1803)  Text 5.1

Dalton Model of the Atom (pg 107 - 108)
       used chemical symbols to show what was occurring during chemical reaction
Experimental (empirical) evidence for existence of atoms (discontinuous theory of matter)
        law of definite composition (Proust)
        law of multiple proportions
        law of conservation of mass

Dalton's Postulates of Atomic Theory

Story: Daltonism = colorblindness

(Will start Cathode Ray Tube next lesson)

Cathode Ray Tube (CRT) William Crookes - great-grandfather of television &
        brother to fluorescent light bulb

    Demonstration:  excitation of cathode rays using a Tesla coil.
         Student volunteer to light fluorescent tube light holding on to Tesla coil.
J.J. Thomson - discovered that cathode rays were deflected by a magnetic field
        or electric field and realized atoms contained negatively charged particles
        (electrons) Text  5.2  Thomson Model of the Atom (pg 108)

HW: Print off Ch 3 Atomic Structure pdf lecture outline 
         Vocabulary:  Atomic Structure  pdf & Development of the Atomic Theory  pdf (due Friday)

Textbook:  Introductory Chemistry Concepts and Connections 4th Edition  by Corwin  pg 106-108
                    Section 5.1 DALTON MODEL OF THE ATOM (pg 107-108)
Objective:  To describe the Dalton model of the atom.
                    Section 5.2 THOMSON MODEL OF THE ATOM (pg 108)
Objective:  To describe the Thomson plum-pudding model of the atom.
                                    Objective:  To state the relative charge on an electron and a proton.

Notice the deflection of the cathode rays by the magnet.

The gray color are electrons being excited. This is the grandfather of a black & white television.

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