Chapter 33
A radioactive isotope of an element that by itself or in a molecule is used to trace biochemical pathways in plants and organisms
gamma
All the uranium in today's deposits in the future will become
lead
What change in atomic number occurs when a nucleus emits an alpha particle? A beta particle? A gamma ray?
-2, +1, 0
Suppose the half-life of a material is 10 days. You have one 1 kg of the material today. How much of the material would you have after 10 days and 20 days, respectively?
0.5 kg after 10 days, and 0.25 kg after 20 days
A material has a half-life of 1 day. If 2 kg of this material is available today, how much of it was available yesterday, and how much the day before?
4kg yesterday, and 8 kg the day before
When thorium (atomic number 90) decays by emitting an alpha particle, what is the atomic number of the resulting nucleus?
88
How does the number of silver atoms change when time advances each second?
A fixed fraction of silver atoms changes each second.
What is a radioactive tracer?
A radioactive isotope of an element that by itself or in a molecule is used to trace biochemical pathways in plants and organisms
What is the change in the atomic mass number for each of the reactions in the preceding two questions?
Alpha emission -4, beta emission 0
Which of these ejects into the atmosphere the greatest amount of dangerous radiation?
Coal-fired power plants
What kind of rays are X-rays?
Electromagnetic
How can you predict the number of silver atoms there are in the second before the time equal to 0 seconds on the graph?
Find the proportion of atoms that remains after 1 second. Then increase the number of original atoms by the same proportion.
Which of these is electromagnetic radiation?
Gamma radiation
Why aren't gamma rays deflected in a magnetic field?
Gamma rays are electromagnetic radiation and so have no charge. Electric and magnetic fields deflect charges.
Which type of detector senses radiation by the ionization of gas in a tube?
Geiger counter
What did Wilhelm Roentgen discover about a cathode-ray beam striking a glass surface?
It produced X-rays
Which contains the higher percentage of neutrons: large nuclei or small nuclei?
Large nuclei (more than 50%)
Suppose 2 kg of a material has a half-life of 1 day. After how long will NONE of the material remain?
Never
What occurs when a nitrogen nucleus captures an extra neutron?
None of the above
Which of these comprises the least radiation in the everyday environment?
Nuclear power plants
If a certain isotope has a radioactive half-life of 10 years, how much of the isotope will remain at the end of 20 years?
One quarter
Name the two different nucleons.
Proton and neutron
Which of these radiation detectors converts flashes of light into electric signals?
Scintillation counter
How does the time needed go from the original number of atoms to one-half of that number compare with the time needed to go from one-half of the number of atoms to one-quarter of the number?
The time needed to go from the original number of atoms to one-half of that is equal to the time needed to from one-half of the number of atoms to one-quarter.
What did Henri Becquerel discover about uranium?
Uranium emitted radiation that would expose film and could be deflected by electric and magnetic fields.
Why is lead found in all deposits of uranium ore?
Uranium undergoes radioactive decay, transmuting into lead
The discovery of radioactivity closely followed the discovery of
X-rays
An element that undergoes radioactive decay becomes
an entirely different element
Carbon-14 in the atmosphere is transformed from
nitrogen
The strong force is one of the four fundamental forces in nature, and exists
only between particles in the nucleus
