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  • 1. Atomic Theory
    By: Katelin Troy

2. Some History:
Henry Baquel
Found that Uranium ore emitted rays.
3. Marie and Pierre Curie
Worked with radioactivity and discovered threesubatomic particles:
~ Alpha ()
~ Beta ()
~ Gamma ()
These explain electrical charges in an atom.
4. J.J. Thomson
~ Studied charges in a Cathode Ray Tube.
~ Discovered through his experiment that atoms have negatively charged particles.
5. Robert Millikan
~ Worked with charged oil drops in a chamber.
~Discovered the charge and mass of electrons and protons:
Electron
- Charge= -1
- Mass= 9.1094 * 10-28 g
Proton
- Charge = +1
- Mass = 1.6726 * 10^-24g
6. Earnest Rutherford
Worked with gold foil experiment
- Charged particles were aimed at Au atoms.
Conclusions:
- An atom has a small positive middle, aka the nucleus.
- Most of the volume of the nucleus is taken up by electrons.
7. Atomic Structure
~ Proton (p+)
~ Electron (e-)
~ Neutron (n)
electron
electron
electron
nucleus
~protons
~neutrons
8. Nucleus:
~ p+ and n
~ most of atomic mass
~ small
~ positive charge
9. Outside Nucleus:
~ contains e-
~ small light particles
~ occupy most of volume
~ negative charge
10. Atoms are neutral
~ Number of e- = number of p+
There are 3 electrons in this atom, how many protons are there?
11. On the Periodic Table of Elements:
Atomic Number
Symbol
Name
Atomic weight
1
H
Hydrogen
1.0079
12. Mass Number
~ Not on Periodic Table.
~ Number of particles in the nucleus.
~ Equal to number of protons and neutrons.
13. Nuclear Symbols:
Mass #
A
X
Atomic #
Symbol
Z
Examples:
Na
Br
22
80
11
35
14. Isotopes:
Atoms of the same element with different mass numbers.
Example:Hydrogen Isotopes
HydrogenDeuteriumTritium
3
H
H
H
1
2
1
1
1
15. The End
The End
16. Works Cited:
Moore, John, et al. Chemistry The Molecular Science. Belmont, CA: Brooks/Cole, 2011. Print.
17. Photos and Diagrams Cited:
Slide 2: http://www.flickr.com/photos/[email protected]/291472553/sizes/l/in/set-72157594358781695/
Slide 7, 11, 13:
Katelin Troy
Slide 15: http://www.flickr.com/photos/d-kav/4428566547/sizes/o/in/photostream/