Atomic Theory
By: Katelin Troy
Some History:
Henry Baquel
Found that Uranium ore emitted rays.
Marie and Pierre Curie
Worked with radioactivity and discovered three subatomic particles:
~ Alpha ()~ Beta ()~ Gamma (γ)
These explain electrical charges in an atom.
J.J. Thomson
~ Studied charges in a Cathode Ray Tube.
~ Discovered through his experiment that atoms have negatively charged particles.
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^-24 g
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.
electron
nucleus~protons
~neutrons
electron
electron
Atomic Structure
~ Proton (p+)
~ Electron (e-)
~ Neutron (n)
Nucleus:
~ p+ and n
~ most of atomic mass
~ small
~ positive charge
Outside Nucleus:
~ contains e-
~ small light particles
~ occupy most of volume
~ negative charge
Atoms are neutral~ Number of e- = number of p+
There are 3 electrons in this atom, how many protons are there?
On the Periodic Table of Elements:
Atomic Number Symbol
Name
Atomic weight
1
H
Hydrogen
1.0079
Mass Number
~ Not on Periodic Table.
~ Number of particles in the nucleus.
~ Equal to number of protons and neutrons.
Nuclear Symbols:
XA
Z
Mass #
Atomic # Symbol
Examples:
Na22
11 Br80
35
Isotopes:
Atoms of the same element with different mass numbers.
Example: Hydrogen Isotopes
Hydrogen DeuteriumTritium
H HH1
1 11
2 3
The End
The End
Works Cited:
Moore, John, et al. Chemistry The Molecular Science. Belmont, CA: Brooks/Cole, 2011. Print.
Photos and Diagrams Cited:
Slide 2: http://www.flickr.com/photos/52307935@N00/291472553/sizes/l/in/set-72157594358781695/Slide 7, 11, 13:Katelin TroySlide 15: http://www.flickr.com/photos/d-kav/4428566547/sizes/o/in/photostream/
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