?In bombarding atomic nuclei with proton “bullets,” why must the protons be given large

A radioisotope is placed near a radiation detector, which registers 80 counts per second. Eight hours later, the detector registers 5 counts per second. What is the halflife of the radioactive isotope?

Uranium-238 absorbs a neutron and then emits a beta particle. Show that the resulting nucleus is neptunium-239.

Rank the following three types of radiation by their ability to penetrate this page of your text, from highest to lowest. (a) Alpha particle (b) Beta particle (c) Gamma ray

Consider the following atoms: A, carbon-12; B, carbon-14; and C, nitrogen-14. Rank them, from greatest to least, by the number of (a) protons in the nucleus. (b) neutrons in the nucleus. (c) nucleons in the nucleus

Rank the following isotopes from the most radioactive isotope to the least radioactive isotope. (a) Nickel-59, half-life 75,000 years (b) Uranium-238, half-life 4.5 billion years (c) Actinium-225, half-life 10 days

Rank the following in order from the most energy released to the least energy released. (a) Uranium-235 splitting into 2 equal fragments (b) Uranium-235 splitting into 3 equal fragments (c) Uranium-235 splitting into 92 equal fragments

Would you expect an alpha particle to speed up just after it leaves the nucleus? Defend your answer.

Why do different isotopes of the same element have the same chemical properties?

People who work around radioactivity wear film badges to monitor the amount of radiation that reaches their bodies. Each badge consists of a small piece of photographic film enclosed in a lightproof wrapper. What kind of radiation do these devices monitor, and how can they determine the amount of radiation the people receive?

When food is irradiated with gamma rays from a cobalt-60 source, does the food become radioactive? Defend your answer.

“Strontium-90 is a pure beta source.” How could a physicist test this statement?

A pair of protons in an atomic nucleus repel each other, but they are also attracted to each other. Explain.

In bombarding atomic nuclei with proton “bullets,” why must the protons be given large amounts of kinetic energy in order to make contact with the target nuclei?

Which should be more stable: the lithium-5 or the lithium-7 isotope?

Which should be more stable: the lithium-7 or the lithium-8 isotope?

Why is lead found in all deposits of uranium ores?

What are the atomic number and the atomic mass of the element formed when \({ }_{84}^{218} \mathrm{Po}\) emits a beta particle? What are they when the polonium emits an alpha particle? Text Transcription: _84^218Po

Elements heavier than uranium in the periodic table do not exist in any appreciable amounts in nature because they have short half-lives. Yet there are several elements below uranium in the table that have equally short halflives but do exist in appreciable amounts in nature. How can you account for this?

If you make an account of 1000 people born in the year 2000 and find that half of them are still living in 2060, does this mean that one-quarter of them will be alive in 2120 and that one-eighth of them will be alive in 2180? How do the death rates of people and the “death rates” of radioactive atoms differ?

What do the proportions of lead and uranium in rock tell us about the age of the rock?

Radium-226 is a common isotope on Earth, but it has a half-life of about 1620 years. Given that Earth is some 5 billions years old, why is there any radium at all?

Is carbon dating advisable for measuring the age of materials a few years old? How about a few thousand years old? A few million years old?

Why is carbon-14 dating not accurate for estimating the age of materials more than 50,000 years old?

The age of the Dead Sea Scrolls was determined by carbon-14 dating. Could this technique have worked if they had been carved on stone tablets? Explain.

Why will nuclear fission probably never be used directly for powering automobiles? How could it be used indirectly?

The uranium ores of the Athabasca Basin deposits of Saskatchewan, Canada, are unusually pure containing up to 70% uranium oxides. Why doesn’t this uranium ore undergo an explosive chain reaction?

Why is carbon better than lead as a moderator in nuclear reactors?

Uranium-235 releases an average of 2.5 neutrons per fission, whereas plutonium-239 releases an average of 2.7 neutrons per fission. Which of these elements might you therefore expect to have the smaller critical mass?

The original reactor built in 1942 was just “barely” critical because the natural uranium that was used contained less than 1% of the fissionable isotope U-235 (half-life 713 million years). What if, in 1942, Earth had been 9 billion years old instead of 4.5 billion years old? Would this reactor have reached critical stage with natural uranium?

Why is so little plutonium-239 formed within the thorium nuclear reactor?

How does the mass per nucleon in uranium compare with the mass per nucleon in the fission fragments of uranium?

Which process would release energy from gold: fission or fusion? From carbon? From iron?

If a uranium nucleus were to fission into three fragments of approximately equal size instead of two, would more energy or less energy be released? Defend your answer using an illustration from this chapter.

Why does iron not yield energy if it undergoes fusion or fission?

. Is the mass of an atomic nucleus greater or less than the sum of the masses of the nucleons composing it? Why don’t the nucleon masses add up to the total nuclear mass?

Heavy nuclei can be made to fuse—for instance, by firing one gold nucleus at another one. Does such a process yield energy or cost energy? Explain.

Which produces more energy: the fission of a single uranium nucleus or the fusing of a pair of deuterium nuclei? The fission of a gram of uranium or the fusing of a gram of deuterium? (Why do your answers differ?)

. If a fusion reaction produces no appreciable radioactive isotopes, why does a hydrogen bomb produce significant radioactive fallout?

Explain how radioactive decay has always warmed Earth from the inside and how nuclear fusion has always warmed the Earth from the outside.

What percentage of nuclear power plants in operation today are based on nuclear fusion?

Sustained nuclear fusion has yet to be achieved and remains a hope for abundant future energy. Even so, the energy that has always sustained us has been the energy of nuclear fusion. Explain.

One oxygen atom and two hydrogen atoms combine to form a water molecule. At the nuclear level, if one oxygen and two hydrogens were fused, what element would be produced?

If a pair of carbon nuclei were fused, and the product emitted a beta particle, what element would be produced?

Ordinary hydrogen is sometimes called a perfect fuel. This is because it occurs in nearly unlimited supply on Earth, and when it burns, harmless water is the product of the combustion. So why don’t we abandon fission energy and fusion energy, not to mention fossil-fuel energy, and just use hydrogen?

Why might some people consider it a blessing in disguise that fossil fuels are such a limited resource? Centuries from now, what attitudes on the combustion of fossil fuels are our descendants likely to have?

The 1986 accident at Chernobyl, in which dozens of people died and thousands more were exposed to cancer-causing radiation, created fear and outrage worldwide and led some people to call for the closing of all nuclear plants. Yet many people choose to smoke cigarettes in spite of the fact that 2 million people die every year from smoking-related diseases. The risks posed by nuclear power plants are involuntary—risks that we must all share, like it or not—whereas the risks associated with smoking are largely voluntary because each individual chooses whether to smoke. Why are we so unaccepting of involuntary risk but so accepting of voluntary risk?

Your friend Paul says that the helium used to inflate balloons is a product of radioactive decay. Your mutual friend Steve says no way. Then there’s your friend Alison, who frets about living near a fission power plant. She wishes to get away from radiation by traveling to the high mountains and sleeping out at night on granite outcroppings. Still another friend, Michele, has journeyed to the mountain foothills to escape the effects of radioactivity altogether. While bathing in the warmth of a natural hot spring, she wonders aloud how the spring gets its heat. What do you tell these friends?

Speculate about some worldwide changes that would be likely to follow the advent of successful fusion reactors.

Offer some arguments why nations should start embracing the development of thorium nuclear reactors. Follow this up with some arguments why thorium nuclear power reactors should not be built.

What is the half-life of uranium-238?

What happens to a nitrogen atom in the atmosphere that captures a neutron?

Why is there more carbon-14 in living bones than in once-living ancient bones of the same mass?

Which isotope of lead is commonly found within uranium ore deposits.

What happens to the uranium-235 nucleus when it is stretched out?

Is a chain reaction more likely to occur in two separate pieces of uranium-235 or in the same two pieces stuck together?

How is a nuclear reactor similar to a conventional fossilfuel power plant? How is it different?

What three fissionable isotopes work well in the production of energy within a nuclear power plant?

Who discovered that energy and mass are two different forms of the same thing?

In which atomic nucleus do nucleons have the least mass?

How does the mass per nucleon in uranium compare with the mass per nucleon in the fission fragments of uranium?

How does the mass of a pair of atoms that have fused compare to the sum of their masses before fusion?

What kind of container is used to contain plasmas at temperatures of millions of degrees?

What kind of nuclear power is responsible for sunshine?

Throw ten coins onto a flat surface. Move aside all the coins that landed tails-up. Collect the remaining coins. After tossing them once again, remove all coins that landed tails-up. Repeat this process until all the coins have been removed. Can you see how this is related to radioactive half-life? In units of “tosses,” what is the average half-life of 25 coins? 50 coins? 1 million coins?

Repeat the above, but use 10 dimes and 25 pennies. Let the dimes represent a radioactive isotope, such as carbon-14, while the pennies represent a nonradioactive isotope, such as carbon-12. Remove only the dimes when they land headsup. Collect all the pennies, and add them to the dimes that landed heads-up. Questions: Does the number of pennies affect the behavior of the dimes? Say someone gives you two sets of coins. The first set contains 10 dimes and 25 pennies. The second set contains 2 dimes and 25 pennies. Which set of coins has gone through a greater number of tosses? Which set provides the most “radioactivity” after a toss? Which set is analogous to a sample of once-living ancient material?

Calculate your estimated annual dose of radiation, using the EPA’s radiation dose calculator available at http://www.epa.gov/radiation/understand/calculate.html.

Stand one domino upright so that when it topples, it hits two other upright dominos, each of which also hits two other upright dominos, and so forth. Arrange as many upright dominos as you can in this fashion so that they fan out as shown in the accompanying photograph. Your challenge will be to arrange the dominos so that every one of them falls. Topple the first domino and observe your chain reaction. Focus your attention on the sound. This domino chain reaction occurs on a two-dimensional flat surface. What is the dimensional geometry of a nuclear chain? What would happen if a Ping-Pong ball were tossed into a room in which the floor was covered with thousands of set-to-kill spring-action mouse traps? Such an explosive event can be seen by using the keywords “mouse trap chain reaction” for an Internet video search.

Radiation from a point source follows an inverse-square law where the amount of radiation received is proportional to \(1 / d^{2}\), where d is distance. If a Geiger counter that is 1 meter away from a small source reads 100 counts per minute, what will be its reading 2 meters from the source? 3 meters from it? Text Transcription: 1/d^2

Consider a radioactive sample with a half-life of one week. How much of the original sample will be left at the end of the second week? At the end of the third week? At the end of the fourth week?

Which type of radiation—alpha, beta, or gamma— results in the greatest change in mass number? The greatest change in atomic number?

What is the origin of most of the natural radiation we encounter?

Which produces more radioactivity in the atmosphere: coal-fired power plants or nuclear power plants?

Is radioactivity on Earth something relatively new? Defend your answer.

Why doesn’t the repulsive electric force of protons in the atomic nucleus cause the protons to fly apart?

Which have more neutrons than protons: large nuclei or small nuclei?

What role do neutrons play in the atomic nucleus?

In what form is most of the energy released by atomic transmutation?

What change in atomic number occurs when a nucleus emits an alpha particle? A beta particle?

What is the long-range fate of all the uranium that exists in the world today?

What is meant by the half-life of a radioactive sample?