If an atom has 100 electrons, 157 neutrons, and 100

What did Roentgen discover about a cathode-ray beam striking a glass surface?

What kind of rays are X-rays?

What did the Becquerel discover about uranium?

What two elements did Pierre and Marie Curie discover?

Why aren’t gamma rays deflected in a magnetic field?

Distinguish between a rad and a rem.

Do humans receive more radiation from artificial or from natural sources of radiation?

Is the human body radioactive? Explain.

What is a radioactive tracer?

Name the two different nucleons.

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

Why is a larger nucleus generally less stable than a smaller nucleus?

What is the role of neutrons in the atomic nucleus?

Which contains the higher percentage of neutrons: large nuclei or small nuclei?

What is the half-life of Ra-226?

How does the rate of decay of a long-half-life material normally compare with the rate of decay of a short-halflife material?

Which type of detector senses flashes of light produced by charged particles or gamma rays?

What kind of trail is left when an energetic particle shoots through matter?

What is transmutation?

When thorium (atomic number 90) decays by emitting an alpha particle, what is the atomic number of the resulting nucleus?

When thorium decays by emitting a beta particle, what is the atomic number of the resulting nucleus?

What is the change in the atomic mass number for each of the reactions in the preceding two questions?

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

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

When, and by whom, did the first successful intentional transmutation of an element occur?

What occurs when a nitrogen nucleus captures an extra neutron?

Which is more prevalent in the food we eat: carbon-12 or carbon-14?

Write a letter to one of your favorite relatives that will help dispel any notion they may have about radioactivity being something new in the world. Briefly discuss the role of radioactivity in dating ancient objects. Also discuss how radioactivity is a major source of natural heat in Earth’s interior, and cite its role in hot springs and volcanoes.

Why is lead found in all deposits of uranium ore?

If a sample of a radioactive isotope has a half-life of 1 year, how much of the original sample will be left at the end of the second year? At the end of the third year? At the end of the fourth year?

A sample of a particular radioisotope is placed near a Geiger counter, which is observed to register 160 counts per minute. Eight hours later, the detector counts at a rate of 10 counts per minute. What is the half-life of the material?

The isotope cesium-137, which has a half-life of 30 years, is a product of nuclear power plants. Show that it will take 120 years for this isotope to decay to about onesixteenth its original amount.

At 6:00 am a hospital uses its cyclotron to make 1 milligram of the isotope fluorine-18 for use as a diagnostic tool with its PET scanner. The half-life of F-18 is 1.8 hours. How much F-18 is left at 3:00 pm? At midnight? Should the hospital plan to make more F-18 the next morning?

Suppose you measure the intensity of radiation from carbon-14 in an ancient piece of wood to be 6% of what it would be in a freshly cut piece of wood. Show that this artifact is 23,000 years old.

Suppose you want to find out how much gasoline is in an underground storage tank. You pour in 1 gallon of gasoline that contains some radioactive material with a long half-life that gives off 5000 counts per minute. The next day, you remove a gallon from the underground tank and measure its radioactivity to be 10 counts per minute. How much gasoline is in the tank?

Rank these three types of radiation by their ability to penetrate this page of your book, from greatest penetration to least: (a) Alpha particle (b) Beta particle (c) Gamma ray

Consider these three nuclei: A. Th-233; B. U-235; C. U-238. From most to least, rank them by the number of (a) protons in the nucleus. (b) neutrons in the nucleus. (c) electrons that normally surround the nucleus.

Consider the following reactions: A. uranium-238 emits an alpha particle; B. plutonium-239 emits an alpha particle; C. thorium-239 emits a beta particle. (a) Rank the resulting nucleus by atomic number, from highest to lowest. (b) Rank the resulting nucleus by the number of neutrons, from most to least.

In the 19th century, the famous physicist Lord Kelvin estimated the age of Earth to be much less than the present estimate. What information that Kelvin did not have might have allowed him to avoid making his erroneous estimate?

X-rays are most similar to which of the following: alpha, beta, or gamma rays?

Gamma radiation is fundamentally different from alpha and beta radiation. What is this basic difference?

Why is a sample of radioactive material always a little warmer than its surroundings?

Some people say that all things are possible. Is it at all possible for a common hydrogen nucleus to emit an alpha particle? Defend your answer.

Why are alpha and beta rays deflected in opposite directions in a magnetic field? Why aren’t gamma rays deflected?

The alpha particle has twice the electric charge of the beta particle but, for the same kinetic energy, deflects less than the beta in a magnetic field. Why is this so?

How do the paths of alpha, beta, and gamma rays compare in an electric field?

Which type of radiation—alpha, beta, or gamma— produces the greatest change in mass number when emitted by an atomic nucleus? Which produces the greatest change in atomic number?

Which type of radiation—alpha, beta, or gamma— produces the least change in mass number? In atomic number?

Which type of radiation—alpha, beta, or gamma— predominates within an enclosed elevator descending into a uranium mine?

In bombarding atomic nuclei with proton “bullets,” why must the protons be accelerated to high energies if they are to make contact with the target nuclei?

Just after an alpha particle leaves the nucleus, would you expect it to speed up? Defend your answer.

What do all isotopes of the same element have in common? How do they differ?

Why would you expect alpha particles, with their greater charge, to be less able to penetrate into materials than beta particles of the same energy?

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

Which interaction tends to hold the particles in an atomic nucleus together, and which interaction tends to push them apart?

What evidence supports the contention that the strong nuclear interaction can dominate over the electrical interaction at short distances within the nucleus?

Can it be truthfully stated that whenever a nucleus emits an alpha or beta particle, it necessarily becomes the nucleus of another element?

Exactly what is a positively charged hydrogen atom?

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

Radiation from a point source obeys the inverse-square law. If a Geiger counter 1 m from a small sample registers 360 counts per minute, what will be its counting rate 2 m from the source? What will it be 3 m from the source?

Why do the charged particles flying through bubble chambers travel in spiral paths rather than in the circular or helical paths they might ideally follow?

What two quantities are always conserved in all nuclear equations?

If an atom has 100 electrons, 157 neutrons, and 100 protons, what is its approximate atomic mass? What is the name of this element?

When a \({ }_{84}^{218} R\) nucleus decays by emitting an alpha particle, what is the atomic number of the resulting nucleus? What is the resulting atomic mass number?

When a nucleus of \({ }_{84}^{218} \mathrm{Po}\) emits an alpha particle, what are the atomic number and the atomic mass number of the resulting element?

When a nucleus of \({ }_{84}^{218} \mathrm{PO}\) emits a beta particle, it transforms into the nucleus of a different element. What are the atomic number and the atomic mass number of this "daughter" element?

Which has the greater number of protons: U-235 or U-238? Which has the greater number of neutrons?

State the number of neutrons and protons in each of these nuclei: \({ }_{1}^{2} H,{ }_{6}{ }^{12} \mathrm{C},{ }_{26}^{56} \mathrm{Fe},{ }_{79}^{197} \mathrm{Au},{ }_{38}^{90} \mathrm{Sr}\), and \({ }_{92}^{238} \mathrm{U}\). Equation Transcription: Text Transcription: _1 ^2 H, _6 ^12 C, _26 ^56 Fe, _79 ^197 Au, _38 ^90 Sr _92 ^238 U

How is it possible for an element to decay “forward in the periodic table”—that is, to decay to an element with a higher atomic number?

How could an element emit alpha and beta particles and result in the same element?

When radioactive phosphorus (P) decays, it emits a positron. Will the resulting nucleus be another isotope of phosphorus? If not, what will it be?

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

A friend suggests that nuclei are composed of equal numbers of protons and electrons, and not neutrons. What evidence can you cite to show that your friend is mistaken?

Radium-226 is a common isotope on Earth, but it has a half-life of about 1600 years. Given that Earth is some 5 billion years old, why is there any radium left at all?

Your friend says that the helium used to inflate balloons is a product of radioactive decay. Another friend disagrees. With whom do you agree?

Another friend, fretful about living near a fission power plant, wishes to get away from radiation by traveling to the high mountains and sleeping at night on granite outcroppings. Comment on this.

Still another friend 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 her?

A friend produces a Geiger counter to check the local normal background radiation. It clicks randomly but repeatedly. Another friend, whose tendency is to fear most that which is least understood, makes an effort to avoid Geiger counters and looks to you for advice. What do you say?

Why is carbon dating ineffective in finding the ages of dinosaur bones?

Is carbon dating appropriate for measuring the age of materials that are a few years old? A few thousand years old? A few million years old?

Make up two multiple-choice questions to check a classmate’s understanding of radioactive dating.

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 one-eighth of them alive in 2180? What is different about the death rates of people and the “death rates” of radioactive atoms?

Judging from Figure 33.22, how many alpha and beta particles are emitted in the series of radioactive decay events from a U-238 nucleus to a Pb-206 nucleus? Does it matter which path is followed?

Elements above 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 atomic number with equally short half-lives that do exist in appreciable amounts in nature. How can you account for this?

Although coal contains only minute quantities of radioactive materials, there is more radiation emitted by a coal-fired power plant than a fission power plant simply because of the vast amount of coal that is burned in coalfired plants. What does this indicate about methods of preventing the release of radioactivity that are typically implemented at the two kinds of power plants?

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

When the author attended high school some 60 years ago, his teacher showed a piece of uranium ore and measured its radioactivity with a Geiger counter. Would that reading for the same piece of ore be different today?