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Updated 1/11/2015

Chemistry A

Nuclear

Chemistry


Updated 1/11/2015

Worksheet #1 : Radioactivity

Chemical reactions involve changing one substance into another substance by rearranging atoms.

However, during a chemical reaction atoms of one element cannot change into atoms of another element. The

reason this change cannot occur is that chemical reactions only involve an atom's electrons – the nucleus

remains unchanged.

Recall that an atom's identity is based on its number of protons. Since protons are in the nucleus and

chemical reactions do not involve the nucleus, the atom remains unchanged. However, there are some reactions

that do involve changes in the nucleus. These are called nuclear reactions and do change one atom of an

element into an atom of a different element.

1. Fill in the table below as a review. You will need your periodic table for this! Remember the atomic

number (or # of protons) determines the element. If you have four protons and seven neutrons you have

beryllium. The same is true if you have four protons and six neutrons...you still have beryllium.

Isotope Total Protons

(Atomic #)

Total Neutrons

(Mass # - Atomic #)

Mass

Number*

Total Electrons

Outside Nucleus

Format for Nuclear

Equation

K-40 19 21 40 19

K40

19

Li-6 Li6

3

2 1

I131

53

90 38

*NOTE: Do NOT use the mass numbers from your periodic table.

Radioactivity is when a substance spontaneously emits radiation. Radioactive atoms (or radioisotopes)

emit radiation because their nuclei are unstable. Unstable nuclei lose energy by emitting radiation in a

spontaneous process called radioactive decay. Unstable radioactive atoms undergo radioactive decay until they

form stable nonradioactive atoms. There are several types of radiation emitted during radioactive decay.

Types of Radiation: Alpha, Beta, and Gamma

Three types of radiation have been discovered. The types are called alpha, beta and gamma. Alpha rays

turned out to be small particles of matter with a charge of +2 and a mass of 4 amu. It has been proved that an

alpha particle contains two protons and two neutrons – it is identical to the nucleus of a helium atom. In fact,

when an alpha particle slows down and gains two electrons it becomes a helium atom. The Greek letter alpha

(α) is used to represent this particle but in equations to keep track of mass and protons we must use He4

2 . Betas

were also found to be particles; they are simply high speed electrons. We use the Greek letter beta (β), but in

equations e0

1 is used. When a beta slows down it becomes an electron. Gamma rays (γ) are not particles; they

are high energy electromagnetic radiation. They are photons (light) with no charge or mass so we simply write

00 in our equations.

Example 1: Thorium-232 decays by emitting an alpha and a gamma.

Th232

90 He4

2 + γ + Ra228

88


Updated 1/11/2015

Example 2: Uranium-239 decays by emitting a beta and a gamma.

U239

92 e0

1 + γ + Np239

93

In the above examples you should notice that the sum of the masses on the left of the arrow equals the sum of

the masses on the right of the arrow and that the sum of the protons on the left equals the sum of the protons on

the right.

2. Complete the following table.

Name Charge Mass Greek Symbol Equation Symbol Identity

ALPHA

BETA

GAMMA

When an atom undergoes radioactive decay the product nucleus is often unstable and undergoes further

decay. This occurs until a stable nucleus is produced. (There is no way for a student to know how an atom will

decay. We will always tell you the mode of decay for equations.)

3. Write the nuclear equations for the following radioactive decay series. Use the periodic table in your book.

uranium-235 emits an alpha ___________________________________________

thorium-231 emits a beta and a gamma ___________________________________________

protactinium-231 emits an alpha and a gamma ___________________________________________

actinium-227 emits a beta ___________________________________________

Th-227 emits an alpha and a gamma ___________________________________________

Ra-223 emits an alpha ___________________________________________

Rn-219 emits an alpha ___________________________________________

Po-215 emits an alpha and a gamma ___________________________________________

The product from above emits a beta ___________________________________________

The product from above emits an alpha ___________________________________________

The product from above emits a beta and a gamma ___________________________________________

4. Using a full sheet of graph paper, graph this U-235 decay series. Have atomic number on the x-axis and

mass number on the y-axis. Instead of dots make a circle and write the symbol for the element inside the circle.

Connect the points as you make the graph, writing α, β or γ on the line to indicate the mode of decay. Make

sure your graph has an appropriate title and covers at least half of the page.

NOTE: notice that 92 – [-1] = 93; there is

always an increase in the atomic number with

beta emission.


Updated 1/11/2015

Decay Series for U-235 Graph


Updated 1/11/2015

Worksheet # 2: Half-life

1. What is a radioactive isotope_____________________________________________________________

2. What is radioactive decay? ______________________________________________________________

3. What is half-life? ______________________________________________________________________

4. If we start with 400 atoms of a radioactive substance, how many would remain after one halflife?_________

after two half-lives? _________ after three half-lives? _________ after four halflives? ________

5. If we start with 48 atoms of a radioactive substance, how many would remain after one halflife?_________

after two half-lives? _________ after three half-lives? ___________ after four halflives?_______

6. If we start with 16 grams of a radioactive substance, how much will remain after three half-lives?________

7. If we start with 120 atoms of a radioactive substance, how many will remain after three half-lives?________

Use the following graph to answer questions 8-11…

8. How long is a half-life for C-14?____________

9. If only 25% of the carbon-14 remains, how old is the

material containing the carbon-14? ________

10. If a sample originally had 120 atoms of C-14, how

many atoms will remain after 16,110 years? _______

11. If a sample known to be about 10,740 years old has

400 carbon-14 atoms, how many atoms were in the

sample when the organism died? _________

12. Which type of nuclear radiation (beta particles, gamma rays, or alpha particles) can be blocked by…

a) a piece of paper ____________ b) a sheet of aluminum ____________ c) a piece of lead ____________

Use the following chart to answer questions 13-16…

Radioactive Substance Approximate half-life

Radon-222 4 days

Iodine-131 8 days

Radium-226 1600 years

Carbon-14 5730 years

Plutonium-239 24,120 years

Uranium-238 4,470,000,000

13. If we start with 8000 atoms of radium-226, how much would remain after 3,200 years? __________

14. If we start with 20 atoms of plutonium-239, how many would remain after 48,240 years? __________

15. If we start with 60 atoms of uranium-238, how many remain after 4,470,000,000 years? _________

16. If we start with 24 atoms of iodine-131, how many remain after 32 days? ___________


Updated 1/11/2015

Worksheet #3: Bombardment Reactions

So far, the equations we have written have involved natural radioactive decay and therefore natural

transmutation (changing of one element into another element). However, we have learned to cause

transmutation by bombardment of nuclei with high-energy particles. Bombardment allows us to prepare

hundreds of isotopes that do not naturally exist, plus this is the method for the production of transuranium

elements, all of the man-made elements that follow uranium on the periodic table.

Example: Boron-10 is bombarded with a neutron yielding an alpha and another product.

B10

5 + n1

0 He4

2 + Li7

3

Write nuclear equations for the following bombardment reactions.

a. Platinum-196 is bombarded by a deuteron (H-2), producing platinum-197 and a proton.

___________________________________________________________________________________

b. Nitrogen-14 is bombarded by a neutron, producing carbon-14 and a proton.

___________________________________________________________________________________

c. Plutonium-239 plus an alpha yields three neutrons and a transuranium element.

___________________________________________________________________________________

d. Uranium-238 plus a neutron yields a beta and another product.

___________________________________________________________________________________

Review of Nuclear Equations You are to write out the complete nuclear equations for the following reactions. You will need to determine the identity of

the unknown product. ***DON’T FORGET!!! Emission… is a word used to express that something is coming OUT of the nucleus. These should be placed

on the RIGHT of the arrow and subtracted from the nucleus.

***DON’T FORGET!!! Bombardment is a word used to express some particle or radioisotope is forced INTO a nucleus. These

should be added to the target on the LEFT of the arrow.

a. Iodine-131 decays by beta and gamma emission.

___________________________________________________________________________________

b. Polonium-218 decays into lead-214 and another product.

___________________________________________________________________________________

c. Uranium-235 decays by alpha and gamma emission.

___________________________________________________________________________________

d. Nitrogen-14 is bombarded with an alpha, producing a proton and oxygen-17.

___________________________________________________________________________________

HINT:

Neutron = n1

0

Proton = p1

1


Updated 1/11/2015

Worksheet #4: Detection of Radioactivity

Radioactivity is not detectable by any of the human senses. You cannot see, feel, smell, taste, or hear

alphas, betas, gammas, or neutrons. We have to detect the radiation emitted from unstable nuclei by the effects

the radiation has upon matter--radiation ionizes matter and radiation causes some materials to scintillate

(glow or flash light).

When alphas, betas, gammas or neutrons travel through matter they can knock electrons off

atoms or molecules leaving a trail of positive ions behind them along their path. The material only stays

ionizes for a short period of time before absorbing electrons and neutralizing again. Radioactivity was

discovered because the emitted radiation exposes photographic film. When the radiation passes through the

photographic emulsion it leaves a trail of ions and when the film is developed the silver atoms collect along this

trail leaving visible evidence of where the radiation struck the film. Geiger counters detect the electricity

created by these ions and produce a click, move a needle on a dial or move a number on a counter.

When ionizing radiation passes through a chamber filled with a gas saturated with a vapor a tiny

trail of droplets collects on the trail of positive ions produced. This visible track can be photographed

and studied and much of the research on fundamental particles within the nucleus was carried out this

way in devices called cloud chambers. Computer analysis has replaced cloud chambers but they were very

significant research detectors for many years.

Film badges also detect condensation created by radiation. They are worn by X-ray technicians, radiologists

and anyone who works around sources of radiation. The badge tracks each person’s total exposure, and if a

predetermined limit is reached the worker must be assigned to an unexposed workplace for a period of time to

allow the body to recover from any damage due to the exposure.

When radiation strikes some materials it causes their electrons to become excited and to then emit

visible flashes of light (photons). These materials are called phosphors and this process is called

scintillation (or fluorescence). Different phosphors respond to different particles of radiation; zinc sulfide is

an important phosphor for detecting alpha particles. In modern scintillation counters the individual flashes

of light can be multiplied electronically and automatically counted. Scintillation counters are important

detectors for modern research and medicine.

Cloud Chamber Film Badge Geiger Counter


Updated 1/11/2015

Questions on Detection:

1. Which of the human senses can detect radiation?

2. What are the two properties of radiation that allow us to detect it?

3. How does radiation produce ions in matter?

4. What property of an ionized gas allows us to detect radiation?

5. Does a gas remain ionized forever?

For a long period of time?

What happens to the ions in a gas?

6. What element collects on the ions on photographic film?

7. What collects on the ions in a cloud chamber?

8. What is emitted when a material scintillates?

9. Give the name and formula for one material that will scintillate.

10. Name three professions that would involve wearing a film badge:


Updated 1/11/2015

Worksheet #5: Nuclear Power Article and Questions

Commercial nuclear power plants are built to generate electricity. To understand how electricity is produced, it is necessary first to understand atoms, the fission process, nuclear fuel, and nuclear reactors, each of which is described below.

Atoms: The Foundation of Nuclear Energy

The process that produces the heat in nuclear power plants involves atomic energy. Atoms are made of protons, neutrons, and electrons.

Inside the nucleus at the center of each atom are positively charged protons. The number of protons in the nucleus determines which family or element the atom belongs to. For example, all carbon atoms have six protons.

The nucleus also contains uncharged particles called neutrons. Among atoms of the same element, it is the number of neutrons that distinguishes one atom from another. For example, the carbon-12 atom contains six protons and six neutrons in the nucleus; the carbon-14 atom has the same number of protons as carbon-12 (six), but has eight neutrons instead of six. Atoms of the same element containing the same number of protons but different numbers of neutrons are called isotopes. Isotopes are identified by a number after the element name that indicates the total number of protons and neutrons inside the nucleus. This is called the mass number.

Circling the nucleus of each atom at varying distances are tiny, negatively charged electrons. In most atoms there are the same number of electrons as protons, but if there are more electrons than protons the atom is said to have a negative charge. If there are more protons than electrons the atom is said to have a positive charge. If an atom carries either a negative or a positive charge it is called an ion. We can also say this atom is ionized/

1. What is an isotope?

2. What is an ion?

Fission: Splitting the Atom

Particles in the nucleus are held together by a force scientists call "nuclear binding energy." It is possible to overcome the binding energy in some large atoms, such as uranium, causing the atoms to split apart or "fission." The fission process occurs when a free neutron at a suitable speed from the nucleus of one atom enters the nucleus of a fissionable atom. The nucleus of the fissionable atom immediately becomes unstable, vibrates, and splits into two fragments that move apart at a high speed. The kinetic energy (energy of motion) of these fragments is turned into heat when the fission fragments collide with surrounding atoms and molecules.

In addition to the fission fragments and heat, a fissioning nucleus also frees two or three additional neutrons . A nuclear chain reaction occurs when some of these neutrons strike other fissionable atoms, which release still other neutrons. These neutrons, in turn, hit other fissionable atoms. Controlling the rate at which these "free" neutrons are emitted is the key to sustaining and controlling a nuclear chain reaction.

3. What is fission?

4. How is binding energy related to the fission process?


Updated 1/11/2015

5. What are fission fragments?

Reactor Fuel: Uranium and Plutonium

The atom used most often as fuel for nuclear reactors is an isotope of uranium known as uranium-235 (U-235). When uranium is mined, it contains two isotopes: uranium-238 (U-238), which makes up approximately 99.3 percent of mined uranium, and uranium-235 (U-235), which only makes up approximately 0.7 percent of mined uranium. Although uranium is quite common in nature, U-235 is relatively rare. Before uranium can be used as a fuel in a nuclear power plant, the 0.7 percent concentration of U-235 must be enriched (increased) to around a 3 percent concentration.

6. What two fissionable isotopes are used in a fission reactor?

Nuclear Reactors: Controlling Chain Reaction

The reactor is what distinguishes a nuclear power plant from other electric power plants; the rest of the buildings and equipment are similar from plant to plant. Nuclear reactors are machines that contain and control atomic chain reations while releasing heat at a controlled rate. The produced heat turns water into steam, which in turn drives turbine-generators. The reactor consists of the following four main elements:

Fuel. The nuclear fuel is the heart of the reactor. In most U.S. reactors, the fuel consists of pellets of enriched uranium packaged in 12-foot-long metal tubes, called fuel rods.

Control rods. These rods absorb neutrons; they are used to control the rate of the chain reaction. If they are pulled out of the core, the reaction speeds up. If they are lowered into the core, they absorb some of the free neutrons and the reaction slows.

Coolant. A coolant, usually water, is pumped through the reactor to carry away the heat produced by the fissioning of the fuel. This is similar to the water in the cooling system of a car, which carries away the heat built up in the engine. In large reactors, as much as 330,000 gallons of water per minute flow through the reactor core very minute to carry away the heat.

Moderator. Neutrons have a better chance of causing an atom to fission if they move considerably slower than their starting speed after being released by a fissioning nucleus. The material used to slow the neutrons is called the moderator. Fortunately for reactor designers and owners, water is an excellent moderator, so reactors can be moderated by the same water that is used as a coolant.

Although engineering designs are quite complex, these four elements-the fuel, the control rods, the coolant, and the moderator-are the basic components of a nuclear reactor. When the control rods are withdrawn, the uranium fuel begins to fission and release extra neutrons, the neutrons are slowed by the moderator so that they will continue the chain reaction, and the heat is carried away by the coolant. Heat from the fission process turns water into steam; the steam is then used to spin a turbine-generator that produces electric current.

7. What are the fuel rods and what are they made of?


Updated 1/11/2015

8. What are control rods and what are they made of?

9. What is the job of a coolant?

10. What is a moderator?

11. How is electricity produced in a nuclear reactor?

Nuclear Power Plant Safety

Safety is of major importance when deciding to license, build, and operate nuclear power plants. In the United States, operators of nuclear power plants must demonstrate to the U.S. Nuclear Regulatory Commission (NRC)-the independent federal agency responsible for licensing and regulating civilian nuclear facilities-that each plant is designed and built according to safety requirements. Most of these requirements have one overall objective: to prevent or minimize the accidental release of radioactive material from the plant. The routine operation of nuclear power plants must also meet safety requirements.

Several barriers to trap and contain radioactive material are designed into every nuclear power plant. They include:

Fuel pellets: The uranium dioxide fuel material is pressed into pellets to provide a stable form. Fuel rods: The tubes that hold the uranium fuel pellets are made out of a strong metal that prevents the solid

and gas fission products from spreading through the reactor system. Containment building: The entire reactor is surrounded by a massive concrete and steel containment

building. It has the single purpose of preventing radioactive materials from reaching the environment in the event that piping systems inside should leak or break. The concrete in the containment building is typically about three feet thick, lined with 3/4-inch steel. The containment building is designed to protect the reactor from being damaged by the direct hit of a large aircraft or tornado winds up to 300 mph.

In addition to these physical barriers, nuclear power plants are designed and built with several safety systems and backup safety systems. These systems are designed to protect against malfunctions, mistakes, and potential accidents. For example, the most extensively studied accident is called a "loss-of-coolant accident" (LOCA). If the reactor core is not constantly cooled by water, parts of the core can melt, resulting in what's called a meltdown. Even after the control rods shut the reactor down, there is still "decay heat" that requires cooling. To prevent LOCAs, nuclear plants contain several backup systems that can be called on to cool the core if the primary cooling system should stop functioning.


Updated 1/11/2015

12. List and describe three barriers used to control radioactive material.

One concern about nuclear power plants, of course, is an echo of the world's first exposure to nuclear power, the atomic bombs of World War II. Many people fear that a nuclear power plant may go out of control and explode like a nuclear weapon. In spite of experts' insistence that such an event is impossible, a few major disasters have increased the fear of nuclear power plants exploding or failing catastrophically in some other way. Although commercial nuclear power plants cannot explode, they have a demonstrated potential to pass out of the control of their operators, with unpredictable consequences. By far the most serious of those events was the explosion that occurred at the Chernobyl nuclear power plant near Kiev in the Ukraine in 1986.

On April 16 of that year, one of the four power-generating units in the Chernobyl complex exploded, blowing the top off the containment building. (The explosion was caused by hydrogen gas released by the overheating core; it was not a nuclear explosion.) Hundreds of thousands of nearby residents were exposed to dangerous levels of radiation and were evacuated from the area. Radioactive clouds released by the explosion were detected downwind in Scandinavia and western Europe. More than a decade later, the remains of the Chernobyl reactor remain far too radioactive for anyone to spend more than a few minutes near the former reactor core. The Soviet government had, of course, always insisted that such a disaster was impossible.

In the U.S., the most famous nuclear incident to date is the accident at the Three Mile Island nuclear plant in 1979. The reactor suffered a partial meltdown that was contained by the giant, pill-shaped steel vessel containing the core. Some radioactive gas was released to the environment, and a hydrogen explosion raised pressures inside the containment dome to within a few pounds per square inch of the dome's design pressure. Again, experts had reassured the public that the chances against such an event were literally astronomical—comparable to those of a giant meteor striking a major city.

13. Briefly describe the Chernobyl accident.

14. Briefly describe the Three Mile Island accident.

Nuclear waste management

Nuclear wastes can be classified into two general categories, low-level wastes and high-level wastes. Low level wastes consist of materials that release a relatively small level of radiation or that will soon decay to a level where they no longer present a threat to humans and the environment. Storing these materials in underground or underwater reservoirs for a few years or in some other system is usually a satisfactory way of handling these materials.


Updated 1/11/2015

High-level wastes are a different matter. After a period of time, the fuel rods in a reactor are no longer able to sustain a chain reaction and must be removed. These rods are still highly radioactive, however, and present a serious threat to human life and the environment that can be expected to last for tens of thousands of years. These rods and any materials derived from them are considered high-level wastes.

For more than two decades, the United States government has been attempting to develop a plan for the storage of high-level nuclear wastes. At one time, the plan was to bury the wastes in a salt mine near Lyons, Kansas. Objections from residents of the area and other concerned citizens made that plan infeasible. More recently, the government decided to construct a huge crypt in the middle of Yucca Mountain in Nevada for the burial of high-level wastes. Again, complaints by residents of Nevada, the government of Nevada, various scientists, and antinuclear citizens nationwide have delayed the plan. Debate centers on whether Yucca Mountain will adequately contain large amounts of waste for the tens of thousands of years necessary. The government insists that Yucca Mountain is safe and will eventually become the long-term storage site for the nation's high-level radioactive wastes. Until the site is actually put into operation, however (if it is), the wastes slated for burial in it are held in "temporary" storage on the grounds of nuclear power plants throughout the United States.

15. What is the difference between low-level and high-level waste?

16. How does the US plan to store high-level waste?

Nuclear fusion

Many scientists believe that the ultimate solution to the world's energy problems may be in the harnessing of nuclear fusion. A fusion reaction is one in which two small atomic nuclei combine with each other to form one larger nucleus. For example, two hydrogen nuclei may combine with each other to form the nucleus of an atom known as deuterium, or “heavy hydrogen”. Fusion reactions are responsible for the production of energy in stars. Most commonly, four hydrogen atoms fuse in a series of reactions to form a single helium atom. An important product of these reactions is the release of an enormous amount of energy. By weight, a fusion reaction releases many times more energy than does a fission reaction.

The world was introduced to the concept of fusion reactions in the 1950s when first the United States and then the Soviet Union exploded fusion (hydrogen) bombs. The energy released in the explosion of each such bomb was more than 1,000 times greater than the energy released in the explosion of a single fission bomb such as that used by the U.S. in World War II to destroy the city of Hiroshima, Japan.

As with fission, scientists and nonscientists alike expressed hope that fusion reactions could someday be harnessed as a source of energy for everyday needs. This line of research has been much less successful, however, than research on fission power plants. In essence, the problem has been to find a way of producing, in a controlled, sustainable fashion, the very high temperatures (millions of degrees Celsius) needed to sustain fusion. Optimistic reports of progress on a fusion power plant appear in the press from time to time, but some authorities now doubt that fusion power will ever be an economic reality.


Updated 1/11/2015

17. What is fusion?

18. Why is fusion preferred over fission?

19. What are the problems with humans creating a fusion reaction?

Source Citation:

"How a Nuclear Power Plant Works." DISCovering Science. Online ed. Detroit: Gale, 2003. Student Resource Center - Bronze. Thomson Gale. North Farmington High School. 19 Dec. 2007 <http://find.galegroup.com/srcx/infomark.do?&contentSet=GSRC&type=retrieve&tabID=T001&prodId=SRC- 3&docId=EJ2103201784&source=gale&srcprod=SRCS&userGroupName=nfarmington&version=1.0>.

Newton, David E, and Larry Gilman. "Nuclear power." Gale Encyclopedia of Science. Ed. K. Lee Lerner and Brenda Wilmoth Lerner. 3rd ed. Detroit: Gale,

2004. Student Resource Center - Bronze. Thomson Gale. North Farmington High School. 18 Dec. 2007 <http://find.galegroup.com/srcx/infomark.do?&contentSet=GSRC&type=retrieve&tabID=T001&prodId=SRC-3&docId=EJ2166031557&source= gale&srcprod=SRCS&userGroupName=nfarmington&version=1.0>.

SCHEMATIC OF A NUCLEAR REACTOR

TURBINE GENERATOR

PRESSURIZER

HEAT EXCHANGER

CONDENSER

PUMP

CONTROL RODS

NUCLEAR FUEL

REACTOR

PUMP

REACTOR WATER

CONDENSER WATER

STEAM

COOLING WATER

ELECTRICITY


Updated 1/11/2015

Nuclear Reactions Review

You are to write out the complete nuclear equations for the following reactions. You will need to determine the identity of

the unknown product.

***DON’T FORGET!!! Emission… is a word used to express that something is coming OUT of the nucleus. These should be placed

on the RIGHT of the arrow and subtracted from the nucleus.

***DON’T FORGET!!! Bombardment is a word used to express some particle or radioisotope is forced INTO a nucleus. These

should be added to the target on the LEFT of the arrow.

HINT:

Neutron = n1

0 Mass of 1amu with NO charge. Proton = H1

1 mass of 1amu, charge of +1

1. Radon-222 decays by alpha emission to produce polonium and an alpha particle.

____________________________________________________________________________________________

2. Lead-214 decays producing a beta and bismuth-214.

____________________________________________________________________________________________

3. Beryllium-8 decays producing an alpha particle and another product.

____________________________________________________________________________________________

4. Cobalt-60 produces nickel-60 and another product.

____________________________________________________________________________________________

5. Polonium-218 decays into lead-214 and another product.

____________________________________________________________________________________________

6. Technetium-99 decays and produces a gamma and technetium-99.

____________________________________________________________________________________________

7. Radon-222 decays producing an alpha, a gamma, and another product.

____________________________________________________________________________________________

8. Cesium-137 decays producing a gamma, barium-137 and another product.

____________________________________________________________________________________________

9. Iodine-127 decays producing xenon-127, a gamma and another product.

____________________________________________________________________________________________

10. Hydrogen-3 decays by beta emission.

____________________________________________________________________________________________

OVER FOR MORE QUESTIONS…


Updated 1/11/2015

11. Uranium-238 is bombarded with a neutron producing neptunium-239 and a beta particle.

____________________________________________________________________________________________

12. Copper-63 is bombarded with an alpha particle producing a neutron and gallium-66.

____________________________________________________________________________________________

13. Rutherford produced the first transmutation of elements. He bombarded nitrogen-14 with this particle and produced

oxygen-17 and hydrogen-1.

____________________________________________________________________________________________

14. The element curium was first made by bombardment. An element was bombarded with an alpha particle.

The products were curium-242 and a neutron.

____________________________________________________________________________________________

15. The element californium was first synthesized by bombardment. An element was bombarded with an alpha particle.

The products were Cf-245 and a neutron.

____________________________________________________________________________________________

16. When lithium-6 is bombarded with a neutron the products are hydrogen-3 and another product.

____________________________________________________________________________________________

17. Hydrogen-2 and hydrogen-3 combine to form helium-4 and a neutron.

____________________________________________________________________________________________

18. Hydrogen-2 and another atom combine to make helium-3 and a neutron.

____________________________________________________________________________________________

19. Uranium-235 plus a neutron yields cesium-144, 2 neutrons, and another product.

____________________________________________________________________________________________

20. Plutonium-239 is bombarded with a neutron producing krypton-92, 3 neutrons and another product.

____________________________________________________________________________________________


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Nuclear Review Sheet

1. Atoms that have unstable nuclei and will change into a different atom are said to be:

A. Fluorescent B. Isotopes C. Radioactive D. Colorful

2. Alpha particles have ____ charge. A. Positive B. Negative C. No

3. The identity of an element is determined by its number of…

A. Electrons B. Neutrons C. Protons + neutrons D. Protons

4. Atoms of the same element with different masses are called:

A.Isotopes B. Radioactive C. Semiconductors D. Transuranium

5. Which radiation has the poorest penetration? A. Alpha particles B. Beta particles C. Gamma rays

6. A beta particle is a/an: A. Electron B. Helium nucleus C. Proton D. Hydrogen nucleus

7. Which radiation can be stopped by a piece of metal foil?

A. Alpha particle B. Beta particle C. Gamma rays D. X-rays

8. The product of a decay reaction has a mass that has decreased by 4. What type of decay occurred?

A. Gamma decay B. Fission C. Alpha decay D. Beta decay

9. The product of a nuclear decay did not change mass or atomic number. What type of decay occurred?

A. Fusion B. Alpha decay C. Gamma decay D. Beta decay

10. The changing of one element into another by a nuclear reaction is called:

A Transmutation B. Transuranium C. Decomposition D. Combustion

11. The half life of a radioisotope is 3 days. If you started with 600 mg of material, how much would be left in 15 days?

A. 18.75mg B. 75 mg C. 37.5 mg D. Can not determine

12. You start with 800 grams of a radioisotope. In 36 hours, there are 100 grams left. What is the half-life of this

radioisotope? A. 3 hours B. 12 hours C. 22 hours D. 10 hours

13. To balance a nuclear reaction, the mass number on both sides of the equation must be equal but the atomic number can

be different. A. True B. False

14. Describe the function of the fuel rods, control rods, moderator, and coolant in a fission reactor.


Updated 1/11/2015

15. What is the difference between fission and fusion?

16. Why isn't fusion currently used to produce energy?

17. What product of fission is used to produce electricity? Describe the process.

18. Complete the following chart:

isotope symbol isotope name atomic number mass number protons neutrons electrons

hydrogen-2

49 67

85 210

228Ac 228


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Nuclear

Chemistry

Supplemental

Packet


Updated 1/11/2015

Supplemental Worksheet #1: Your Annual Radiation Dose

The Roentgen Equivalent Man, or REM, is the unit used most frequently to measure radiation exposure/effect on humans. This unit takes into account not only the amount of radiation you are exposed to but also how sensitive your body is to a particular type of radiation. Fill in the following blanks with suitable values. You may need to look up some information on the internet. When you finish, add the quantities to estimate your annual radiation dose.

SOURCE OF RADIATION QTY PER YEAR 1. Location of your community a. Cosmic radiation (radiation emitted by stars across the universe. Much of this is deflected by the earth’s atmosphere and ionosphere.) sea level (U.S. Average). Find your dose value based on your community’s elevation

sea level: 26 mrem 4000-5000 ft 47 mrem 0-1000 ft 28 mrem 5000-6000 ft 52 mrem 1000-2000 ft 31 mrem 6000-7000 ft 66 mrem 2000-3000 ft 35 mrem 7000-8000 ft 79 mrem 3000-4000 ft 41 mrem 8000-9000 ft 96 mrem

28 mrem

2. Terrestrial Radiation (from the ground) If you live in a state bordering the Gulf or Atlantic coasts 16 mrem If you live in AZ, CO, NM, or UT 63 mrem If you live anywhere else in the US 30 mrem

3. House construction material. (Building materials contain a very small percent of radioisotopes.) If your house is stone, adobe, brick or concrete 7 mrem

___ mrem

4. Power Plants If you live within 50 miles of a nuclear power plant 0.009 mrem If you live within 50 miles of a coal-fired power plant 0.03 mrem

___ mrem 5. Food, water, and air. From food (C-14 and K-40) and water (Rn dissolved in water) 40 mrem From air (Rn) 200 mrem

___ mrem 6. How you live Weapons test fallout 1 mrem Travel by jet aircraft (per hour in air) 0.5 mrem If you have porcelain crowns or false teeth 0.07 mrem If you wear a luminous wristwatch 0.06 mrem If you go through airport security (each time) 0.002 mrem If you watch TV 1 mrem If you use a video display (computer screen) 1 mrem If you live in a dwelling with a smoke detector 0.008 mrem If you use a gas camping lantern with an old mantle 0.2 mrem If you wear a Pu powered pacemaker 100 mrem

___ mrem ___ mrem ___ mrem ___ mrem ___ mrem ___ mrem ___ mrem ___ mrem ___ mrem ___ mrem

7. Medical and dental X rays (dose per procedure X-ray Extremity (arm, hand, foot, or leg) 1 mrem Dental 1 mrem Chest 6 mrem Pelvis/hip 65 mrem Skull/neck 20 mrem Barium enema 405 mrem Upper GI 245 mrem CT scan (head and body 110 mrem Nuclear medicine (e.g. thyroid scan) 14 mrem

___ mrem ___ mrem ___ mrem ___ mrem ___ mrem ___ mrem ___ mrem ___ mrem ___ mrem

Total ___ mrem


Updated 1/11/2015

After calculating your annual radiation dose, answer these questions:

1. How does your yearly radiation dose compare with the US limit of 500 mrem?

2. Compare your value compare to the average background radiation of 360-mrem

3. Why is it useful to monitor how many X-rays you receive annually?

4. When choosing a place to live, what factors might decrease you annual ionizing dose?

5. What are some lifestyle changes that could reduce a person’s exposure to ionizing radiation?

6. Would you want to make those changes? Explain.


Updated 1/11/2015

Supplemental Worksheet #2: A Brief History of Radioactivity

WILHELM ROENTGEN (1845-1923)

While working with gas discharge tubes (cathode ray tubes) in 1895 Roentgen discovered x-rays. In the

gas discharge tube electrons leave the negative electrode (the cathode) and speed down the tube to strike the

anode (positive electrode). When these high speed electrons strike the metal of the anode it emits x-rays. He

first detected them due to scintillations (flashes of light) produced in zinc sulfide but quickly learned that they

exposed photographic plates or film.

HENRI BECQUEREL (1852-1908)

In 1896 Becquerel was studying the fluorescence and phosphorescence of the ore of uranium called

pitchblende. He would expose the ore to the UV radiation in sunlight and then measure the visible light

produced using photographic plates. One cloudy day he put the pitchblende in a drawer on top of some

photographic plates, upon opening the drawer the next day, he discovered that without any excitation the

pitchblende was spontaneously giving off energy that would penetrate the wrapping and expose the

photographic plates--Becquerel had discovered radioactivity.

PIERRE CURIE (1859-1906), MARIE SKLODOWSKA CURIE (1867-1934)

In 1897 Pierre and Marie Curie were continuing the investigation of Becquerel's discovery--

radioactivity. They noted that pitchblende was more radioactive than pure uranium. This lead them to study the

composition of the ore where they discovered two previously unknown and highly radioactive elements, radium

and polonium. For this work Pierre and Marie shared the 1903 Nobel Prize in Physics with Becquerel. In 1906

Pierre walked in front of a horse drawn wagon and was killed instantly. Marie continued their work,

concentrating on isolating a measurable sample of pure radium from tons of pitchblende. After ten years of

work she was successful and for this effort was awarded the 1911 Nobel Prize in chemistry. Marie Curie died

of leukemia which was most likely induced by exposure to radiation. Even after the dangers of radiation were

well known she refused to follow accepted safety procedures and willing exposed herself to dangerous amounts

of radiation.

Becquerel detected radiation because it exposed photographic plates. The Curies developed a method

for measuring the amount of radiation using the rate of discharge of an electroscope. An electroscope is a glass

jar with a metal rod inserted leading to a pair of foil leaves (this sheets of metal foil). When an electroscope is

charged the leaves repel each other and push apart; as the electroscope loses it charge the leaves fall down due

to gravity. When radiation travels through air it ionizes the air leaving a trail of positive ions. These ions can

take electrons from the electroscope causing it to discharge. A lot of radiation means a lot of ions and a rapid

discharge, a little radiation means few ions in the air and a much slower rate of discharge.

charged electroscope partially discharged electroscope discharged electroscope


Updated 1/11/2015

ERNEST RUTHERFORD (1871-1937)

Ernest Rutherford is credited with most of the early work sorting "radiation" from a radioactive source

into alpha, beta and gamma. That is, he figured out that "radiation" being emitted from pitchblende or any other

source was not just a single thing but consisted of positive and negative particles and high energy photons. He

placed his radioactive sample in a block of lead with a hold drilled in it in order to produce a straight narrow

beam of radiation. He arranged a screen coated with zinc sulfide around the opening in the lead in order to

detect the radiation. With this set up all of the "scintillations" occurred on the screen at a point straight across

from the hole in the block of lead. However, when he placed metal plates with electrical charges behind the

screen he found the scintillations happened at three sites--some "radiation" was being attracted by the negative

plate (alphas), some by the positive plate (betas) and some remained unaffected and traveled straight (gammas).

_ _ _ _ _ _ _ _ Metal plate with negative charge

_____________________

Screen coated with ZnS

_____________________

+ + + + + + + + + + + Metal plate with positive charge

He identified alphas as helium nuclei, betas as high speed electrons and gammas as high energy electromagnetic

radiation. He also put forth the term "transmutation" to describe how one element turns into another when it

undergoes radioactive decay. For his work Rutherford, who considered himself a physicist, received the 1908

Nobel Prize in Chemistry. In his acceptance speech he announced that he felt he had been transmutated from a

physicist to a chemist.

Questions on History:

1. What type of radiation is produced when electrons strike a metal target? ____________________

How was this radiation first detected? __________________________________________________

2. What was Becquerel studying in his lab? _______________________________ What discovery did

these studies lead him to? ____________________________________________________________

3. What elements did the Curies discover? _________________________________________________

How did the Curies die? ______________________________________________________________

4. Explain what an electroscope does and how it works.

5. Name a material that makes a good shield against radiation. _________________________________

6. How did Rutherford produce a narrow beam of "radiation"? __________________________________

7. Why didn't the alphas, betas and gammas all travel the same distance in Rutherford's experiment?


Updated 1/11/2015

Supplemental Worksheet #3: Uses and Biological Effects of Radioactivity

Use pages 828-831 in the textbook, Chemistry: Matter and Change by Glencoe to complete the following

questions.

Uses of Radiation

1. What method is used to detect trace amounts of elements in samples? _____________________

2. What are radioisotopes used for? __________________________________________________

3. How is CO2 used in the study of glucose formation in photosynthesis? ________________________

_______________________________________________________________________________

4. What isotope of carbon is in this CO2? _________________________________

5. What is the name given to a radioisotope that emits non-ionizing radiation and is used to signal the

presence of an element? ________________________________

6. What radiotracer is used to detect diseases of the thyroid gland? Briefly describe how this detection

works. _________________________________________________________________________

_____________________________________________________________________________

7. What is PET? How are the gamma rays produced in the patient’s body? _____________________

________________________________________________________________________________

________________________________________________________________________________

8. What is a drawback of radiation therapy in our fight against cancer? _________________________

________________________________________________________________________________

Biological Effects of Radiation

1. List the three factors affecting the amount of damage ionizing radiation can cause. _____________

________________________________________________________________________________

2. What type of radiation…

easily penetrate human tissue? ____________________________

stopped by skin? _______________________________

penetrates 1-2 cm beneath the skin? _______________________

3. What is a free radical and what can it do to a biological system? ____________________________

________________________________________________________________________________


Updated 1/11/2015

4. Clearly describe somatic damage and genetic damage. ___________________________________

________________________________________________________________________________

________________________________________________________________________________

________________________________________________________________________________

5. Two units used to measure radiation doses are the rad which stands for _______________________

__________________ and the rem which stands for _____________________________________.

6. Complete the table below:

Effects of Short-term Radiation Exposure

Dose (rem) Effects on Humans

7. You are exposed to radiation on a regular basis. Complete the table of annual exposures.

Average Annual Radiation Exposure

Source Average Exposure (mrem/yr)

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