Nuclear Model of the Atom
Objectives:
 Summarize the experimentation that led to the nuclear model of the atom
 Summarize the nuclear model of the atom
J.J. Thomson (experimentation from 1895-1897)
define cathode ray tube-
• A vacuum tube has had all gases
pumped out of it.
• At each end of the tube is a metal
piece called an electrode, which is
connected through the glass to a
metal terminal outside the tube.
• These electrodes become electrically charged when they are
connected to a high-voltage electrical source.
define electron- invisible, negatively charged particles
define proton- positively charged particles
Eugen Goldstein (experimentation in 1869-1896)
mass of a proton= 1.67x10-24 grams or 1 amu
define plum pudding model of the atom-
spherical cloud of positive mass dotted with
negatively charged electrons
How can I justify the structure of the atom based
on historical experimentation?
T. O’Toole
Rutherford (experimentation from 1909-1911)
Gold Foil Experiment
OBSERVATIONS
CONCLUSIONS
1. Atoms are mostly empty
space (most of the alpha
particles went through the
gold foil)
2. Small and dense part of the
atom (few alpha particles
were able to hit it)
3. Dense part is positively
charged (alpha particles were
positively charged and they
were deflected back i.e.
repelled)
Rutherford's Nuclear Model of the Atom
Please keep in mind that at this point—the electrons
are merely on the outside of the nucleus and there
are no neutrons.
Minute Paper (also on Portfolio Page)
How can I justify the structure of the atom based
on historical experimentation?
T. O’Toole
How do I get from where I am to where I’m going?
The 10 Minute Makeover
Customize your learning by choosing from the following options each night
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Complete the appropriate section on the Portfolio Page
Complete SYS Assignment related book work
Review the PPT file on the website
Read pages 109-112 in the book
Answer question #5 on page 112. The answer is in Appendix C.
Use the Flash Animation that can be found on the Glogster
(http://www.mhhe.com/physsci/chemistry/essentialchemistry/fl
ash/ruther14.swf) to review the Gold Foil Experiment and its
conclusions
Use the Shockwave Animation that can be found on the Glogster
(http://chemmovies.unl.edu/ChemAnime/CATHRAYD/CATHRAYD
.html) to review the Cathode Ray Tube experiments for the
discovery of the electron
Check out the tutorial resources in the LiveBinder
Review the skills from today’s Train Your Brain
How can I justify the structure of the atom based
on historical experimentation?
T. O’Toole