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Homework exercises on Nuclear Reactions for a Physical Science course. Also refer to atomic energy, reactor, bomb, isotopes, Uranium, Einstein, radioactivity, WBT, courseware, Ron Kurtus, School for Champions. Copyright © Restrictions
Nuclear Reactions - Homework Answers
After you have completed the Nuclear Reactions Homework, you can refer to these answers. Although it is better to have known the answer from your reading, the process of writing the correct answer on your homework sheet will help you remember the concepts.
1. Why don't protons in a nucleus repel each other?
They are held together by a "nuclear glue" or a force.
2. Why isn't the atomic weight of an atom exactly the total of the number of protons and neutrons?
The atomic weight of protons and neutrons are not exactly 1.0. Also some of the mass is used in the forces keeping the nucleus together..
3. How much does each electron add to the atomic weight?
Each electron weighs only about 1/1200 of a proton.
4. Why are there usually more neutrons than protons in the nucleus?
It seems to have something to do with keeping the nucleus stable.
5. What is an isotope?
An atom with a nucleus that has more or less neutrons than the typical nucleus for that atom.
6. What determines if a nucleus is unstable?
Too many or too few neutrons. But there is no real formula for it..
7. What happens to an unstable nucleus?
It gives off particles and radiation until it becomes stable. It may even split.
8. How is the rate of decay of an unstable nucleus measured?
by the half-life, which is the time it takes 1/2 the nuclei to decay..
9. What practical application is there of knowing the half-life of an unstable isotope?
It is used to measure the age of materials, especially very old items for substances that have a half-life in the order of millions of years..
10. What particles and rays are emitted from a radioactive nucleus?
Electrons, neutrons, beta particles, gamma rays.
11. Is radioactivity harmful to people? Why or why not?
Radioactivity can cause life-threatening burns, as well as cancer..
12. Why is Uranium radioactive?
Its nucleus is unstable.
13. What happens when Uranium-235 is struck by a neutron?
It splits into two and gives off radiation and other neutrons. The splitting has much energy.
14. How does a nuclear chain reaction occur?
One atom splits, causing many more to split, causing even more to split, and so on..
15. How do they control a nuclear chain-reaction?
They use buffer materials such as carbon rods to slow down the reaction.
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