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Name ___________________________________ Date ________________ Class _______________

Unit 3 Study Guide: Atomic Structure and Nuclear Energy

Section 4.1 Early Ideas About Matter

For each statement below, write true or false.

_______________ 1. Ancient philosophers regularly performed controlled experiments. _______________ 2. Philosophers formulated explanations about the nature of matter based on their own experiences. _______________ 3. Both Democritus and Dalton suggested that matter is made up of atoms. _______________ 4. Dalton's atomic theory stated that atoms separate, combine, or rearrange in chemical reactions. _______________ 5. Dalton's atomic theory stated that matter is mostly empty space. _______________ 6. Dalton was correct in thinking that atoms could not be divided into smaller particles. _______________ 7. Dalton's atomic theory stated that atoms of different elements combine in simple whole-number ratios to form compounds. _______________ 8. Dalton thought that all atoms of a specific element have the same mass. _______________ 9. Democritus proposed that atoms are held together by chemical bonds, but no one believed him. _______________ 10. Dalton's atomic theory was based on careful measurements and extensive research.

Section 4.2 Defining the Atom

For each item in Column A, write the letter of the matching item in Column B.

Column A Column B

________ 1. Proposed the nuclear atomic model ________ 2. Determined the mass-to-charge ratio of an electron ________ 3. Calculated the mass of an electron

a. Thomson

b. Millikan

c. Rutherford

Draw and label a diagram of each atomic model.

4. plum pudding model

5. nuclear atomic model

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Complete the following table of proton, electron, and neutron characteristics.

Particle Symbol Location Relative Charge

Relative Mass

6. Proton

7. n

8.

1/1840

Section 4.3 How Atoms Differ

For each statement below, write true or false.

_______________ 1. The number of neutrons in an atom is referred to as its atomic number. _______________ 2. The periodic table is arranged by increasing atomic number. _______________ 3. Atomic number is equal to the number of electrons in an atom. _______________ 4. The number of protons in an atom identifies it as an atom of a particular element. _______________ 5. Most atoms have either a positive or a negative charge.

Answer the following questions.

6. Lead has an atomic number of 82. How many protons and electrons does lead have? ______________

7. Oxygen has 8 electrons. How many protons does oxygen have? ____________________

8. Zinc has 30 protons. What is its atomic number? ____________________

9. Astatine has 85 protons. What is its atomic number? ____________________

10. Rutherfordium has an atomic number of 104. How many protons and electrons does it have?

11. Polonium has an atomic number of 84. How many protons and electrons does it have?

12. Nobelium has an atomic number of 102. How many protons and electrons does it have?

Determine the number of protons, electrons, and neutrons for each isotope described below.

13. An isotope has atomic number 19 and mass number 39.

14. An isotope has 14 electrons and a mass number of 28.

15. An isotope has 21 neutrons and a mass number of 40.

16. An isotope has an atomic number 51 and a mass number 123.

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Answer the following question.

17. Which of the isotopes in problems 13-16 are isotopes of the same element? Identify the element.

Write each isotope below in symbolic notation. Use the periodic table to determine the atomic number of each isotope.

18. neon-22 __________

19. helium __________

20. cesium-133 __________

21. uranium-234 __________

Label the mass number and the atomic number on the following isotope notation.

Circle the letter of the choice that best completes the statement.

25. The mass of an electron is

a. smaller than the mass of a proton. c. a tiny fraction of the mass of an atom.

b. smaller than the mass of a neutron. d. all of the above.

26. One atomic mass unit is

a. 1/12 the mass of a carbon-12 atom. b. 1/16 the mass of an oxygen-16 atom. c. exactly the mass of one proton. d. approximately the mass of one proton plus one neutron.

27. The atomic mass of an atom is usually not a whole number because it accounts for

a. only the relative abundance of the atom's isotopes. b. only the mass of each of the atom's isotopes. c. the mass of the atom's electrons. d. both the relative abundance and the mass of each of the atom's isotopes.

Use the figures to answer the following questions.

27. What is the atomic number of osmium? _______________

28. What is the chemical symbol for niobium? _______________

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29. What is the atomic mass of osmium? _______________

30. What units is the atomic mass reported in? _______________

31. How many protons and electrons does an osmium atom have? A niobium atom?

Calculate the atomic mass of each element described below. Then use the periodic table to identify each element.

Isotope Mass (amu)

Percent abundance

35X 34.969 75.77

37X 36.966 24.23

Section 4.4 Unstable Nuclei and Radioactive Decay

For each item in Column A, write the letter of the matching item in Column B.

Column A Column B

________ 1. The rays and particles that are emitted by a radioactive material ________ 2. A reaction that involves a change in an atom's nucleus ________ 3. The process in which an unstable nucleus loses energy spontaneously ________ 4. Fast-moving electrons

a. nuclear reaction

b. beta radiation

c. radiation

d. radioactive decay

Use the diagram to answer the questions.

5. Which plate do the beta particles bend toward? Explain.

Isotope Mass (amu)

Percent abundance

63X 62.930 69.17

65X 64.928 30.83

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6. Explain why the gamma rays do not bend.

7. Explain why the path of the beta particles bends more than the path of the alpha particles.

Complete the following table of the characteristics of alpha, beta, and gamma radiation.

Radiation Type

Composition Symbol Mass (amu)

Charge

8. Alpha

9.

1/1840

10. High-energy electromagnetic radiation

Section 24.1 Nuclear Radiation

Use each of the terms below just once to complete the passage.

alpha particle radioactivity gamma ray radioisotope beta particles radiation X ray radioactive decay

The discovery of the (1) ____________________ in 1895 by Wilhelm Roentgen opened a whole new field of

research. Among those who worked in this new field were Pierre and Marie Curie. The Curies discovered that

some forms of matter give off (2) ____________________, a combination of particles and energy. Marie Curie

named this process (3) ____________________. Another term used to describe the process by which one

element spontaneously changes into another element is (4)____________________. Any isotope that undergoes

such changes is called a(n) (5) ____________________.

There are three common forms of radiation. One type is a form of energy known as (6)____________________.

The other types of radiation consist of particles. The form of radiation containing the heavier particle is made up of

helium nuclei called (7) ____________________. The form of radiation containing the lighter particle consists of

electrons called (8) ____________________.

Complete each statement.

9. Wilhelm Roentgen discovered the form of energy known as ____________________.

10. The form of nuclear radiation that has the greatest penetrating power is the ________________.

11. When a radioactive nucleus gives off a gamma ray, its atomic number increases by________________.

12. The three types of radiation were first identified by ____________________.

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13. Each alpha particle carries an electric charge of ____________________.

14. Each beta particle carries an electric charge of ____________________.

15. Each gamma ray carries an electric charge of ____________________.

Section 24.2 Radioactive Decay

Circle the letter of the choice that best completes the statement.

1. The number of stable isotopes that exist compared to the number of unstable isotopes is

a. much less. b. much more. c. slightly more. d. about the same.

2. A lightweight isotope is likely to be stable if the ratio of protons to neutrons in its nucleus is

a. 1:2. b. 1:1. c. 2:1. d. 5:1.

3. The only nucleon among the following is the

a. electron. b. positron. c. beta particle. d. neutron.

4. The isotope least likely to be found in the band of stability among the following is

a. b. c. d.

5. The isotope formed by the beta decay of has an atomic number of

a. 18. b. 39. c. 20. d. 21.

6. The isotope formed by the alpha decay of has a mass number of

a. 234. b. 236. c. 238. d. 240.

7. The positron produced during positron emission comes from a(n)

a. neutron. b. proton. c. electron. d. positron.

8. During electron capture, a proton in the nucleus of an atom is converted into a(n)

a. neutron. b. positron. c. electron. d. another proton.

9. When the isotope decays by beta emission, the isotope formed is

a. b. c. d.

10. The isotope formed by the alpha decay of is

a. b. c. d.

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11. The neutron-to-proton ratio for the isotope sodium-23 is

a. 1 : 1.1. b. 1.1 : 1. c. 2.1 : 1. d. 1 : 2.1.

12. The decay of yields and

a. b. e- . c. γ. d. e+ .

13. Atoms located above the band of stability on a graph of numbers of neutrons versus number of protons are usually unstable because they contain too many

a. protons. b. neutrons. c. electrons. d. nucleons.

Section 24.3 Nuclear Reactions

For each statement below, write true or false.

_______________ 1. Transmutation is the conversion of an atom of one element to an atom of another element. _______________ 2. All nuclear reactions involve some type of nuclear transmutation. _______________ 3. Scientists induce transmutations by bombarding stable nuclei with high-energy alpha, beta, or gamma radiation. _______________ 4. The first induced nuclear transmutation was carried out by Marie and Pierre Curie in 1897. _______________ 5. Most induced transmutation reactions are produced in high-energy particle accelerators. _______________ 6. Neptunium and plutonium were the first transuranium elements discovered. _______________ 7. The nuclear formula for a neutron is n. _______________ 8. The half-life of a radioisotope is the time it takes for that isotope to decay. _______________ 9. A radioisotope that decays very rapidly has a short half-life. _______________ 10. Radioisotopes with very long half-lives are seldom found in Earth's crust. _______________ 11. Temperature is the only factor that affects the half-life of a radioisotope. _______________ 12. Carbon dating is not used to measure the age of rocks because the half-life of carbon-14 is too short. _______________ 13. After an organism dies, its ratio of carbon-14 to carbon-12 and carbon-13 increases. _______________ 14. Scientists currently believe that all of the possible transuranium elements have been discovered.

_______________ 15. When an atom of is bombarded with protons, the products are and neutrons. _______________ 16. Mass number and atomic number are conserved in all nuclear reactions.

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_______________ 17. The mass of a 25.0 g piece of (half-life: 2.4 hr) will be reduced to 3.1 g after 7.2 hr.

Use the following diagram to complete the passage.

In a nuclear power plant, energy is produced in the reactor core by fission reactions that occur inuranium-

containing bars called (18) ____________________. The uranium is found at location (19)_________________

in the diagram. The rate at which the nuclear reaction takes place is controlled by other bars called (20)

____________________. These bars of metal are found at location (21) ____________________. One of the

important safety factors in the power plant is a strong dome-shaped structure surrounding the reactor. The

structure is labeled (22) ____________________ in this diagram and called (23) ____________________.

Heat produced by nuclear fission is carried away by (24) ____________________, which enters the core at point

(25) ____________________ in the diagram. It then leaves the core at point (26) ____________________. Heat

from the reactor core is used to boil water in the (27) ____________________, shown at (28)________________

in the diagram. Steam produced here is used to generate electricity at point (29) ____________________ in the

diagram. The steam is then cooled at location (30)____________________ by water from an outside source.

For each statement, write true or false.

_______________ 31. A nuclear reactor produces energy from fuel rods containing uranium-238. _______________ 32. The amount of energy produced for each kilogram of uranium is about the same as the amount of energy from a kilogram of coal. _______________ 33. The only elements that can be used as fuel in a nuclear power plant are those in which a chain reaction can occur. _______________ 34. If more than a critical mass is present in a sample, that sample is said to have supercritical mass.

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_______________ 35. Water is the most common coolant used in a nuclear reactor. _______________ 36. Nuclear power plants usually produce electricity. _______________ 37. The purpose of the control rods in a nuclear reactor is to reflect neutrons back into the core. _______________ 38. The production of energy in a nuclear reactor can be stopped by pulling out all control rods. _______________ 39. A breeder reactor produces more fuel than it uses. _______________ 40. The fission products produced in nuclear power plants are not radioactive. _______________ 41. An uncontrolled chain reaction led to the nuclear accident in Chernobyl, Ukraine.

Section 24.4 Applications and Effects of Nuclear Reactions

For each item in Column A, write the letter of the matching item in Column B.

Column A Column B

______ ______ ______ ______ ______ ______ ______ ______ ______ ______ ______ ______ ______ ______ ______

1. Worn by workers to monitor radiation exposure

2. Contains phosphors that detect radiation

3. Radiation energetic enough to break apart atoms

4. Uses a gas-filled metal tube to detect and measure radiation

5. A material that gives off light when struck by radiation

6. A method used to detect very small amounts of an element in a sample

7. A radioisotope used to indicate the presence of an element in a sample

8. Used to detect disorders of the thyroid gland

9. A procedure that uses positrons to detect many different medical disorders

10. This type of radiation easily penetrates human tissue.

11. Damage caused by radiation that affects a person, but not their offspring

12. Radiation damage that can affect chromosomes and offspring

13. A unit used to measure the amount of radiation absorbed by a body

14. A unit used to measure the amount of damage done to a body

15. The annual amount of radiation to which a person is normally exposed

a. PET

b. Geiger counter

c. 100-300 mrem

d. ionizing radiation

e. rad

f. iodine-131

g. rem

h. genetic damage

i. neutron activation analysis

j. scintillation counter

k. radiotracer

l. gamma ray

m. somatic damage

n. phosphor

o. TLD badge

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Reviewing Vocabulary

Match the definition in Column A with the term in Column B.

Column A Column B

______ ______ ______ ______ ______ ______ ______ ______ ______ ______ ______ ______ ______ ______ ______ ______ ______

1. The difference between the mass of a nucleus and the sum of its nucleons

2. The process in which an atom of one element changes into an atom of another element

3. A force that acts only on subatomic particles that are extremely close together

4. A fusion reaction that takes place only at very high temperatures

5. Isotopes of atoms with unstable nuclei that emit radiation

6. The area on a graph plotting neutrons and protons within which all stable nuclei are found

7. Radiation energetic enough to ionize matter with which it collides

8. The artificial production of a nuclear reaction that involves striking the nuclei with high-velocity charged particles

9. A way of determining the age of very old objects using radioactive materials

10. A form of high-energy electromagnetic radiation

11. A term to describe a sample of fissionable material that is massive enough to sustain a chain reaction

12. Another name for a proton or neutron

13. A radioisotope that emits non-ionizing radiation and is used to signal the presence of an element or specific substance

14. A series of nuclear reactions beginning with an unstable nucleus and resulting in the formation of a stable nucleus

15. Any element with an atomic number greater than 92

16. A transmutation process brought about when an electron is absorbed by a nucleus

17. Reactors able to produce more fuel than they use

a. strong nuclear force

b. band of stability

c. nucleon

d. radioactive decay series

e. induced transmutation

f. thermonuclear reaction

g. critical mass

h. electron capture

i. mass defect

j. breeder reactor

k. transuranium element

l. ionizing radiation

m. transmutation

n. radiochemical dating

o. radiotracer

p. radioisotope

q. X rays

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Understanding Main Ideas

Circle the letter of the choice that best completes the statement or answers the question.

1. The person who named radioactivity as the process in which materials give off rays and particles is

a. Marie Curie. b. Henri Becquerel. c. Wilhelm Roentgen. d. Ernest Rutherford.

2. The most penetrating form of nuclear radiation is

a. alpha rays. b. beta rays. c. gamma rays. d. positrons.

3. In an atom, the strong nuclear force acts on

a. protons only. b. neutrons only.

c. protons and neutrons. d. protons, neutrons, and electrons.

4. During the process of electron capture, an electron from outside the nucleus joins with a proton to form

a. a neutron. b. a positron. c. another proton. d. a gamma ray.

5. The half-life of calcium-47 is about 5 days. Starting with 64 g of this isotope, what would be the amount remaining after 20 days?

a. 32 g b. 16 g c. 8 g d. 4 g

6. One product of all nuclear fission reactions is

a. protons. b. a larger nucleus. c. electrons. d. neutrons.

7. Mass is lost or gained in

a. all chemical reactions. b. all nuclear fission reactions.

c. all nuclear fusion reactions. d. all chemical and nuclear reactions.

8. A chain reaction will NOT take place in a piece of uranium if

a. the temperature is too low. b. there are too many neutrons.

c. there are too few neutrons. d. the piece of uranium is too large.

9. One of the most serious problems surrounding the use of nuclear power plants is

a. finding a way to dispose of spent fuel rods. b. the high cost of coolant needed.

c. a lack of uranium. d. initiating a chain reaction in the fuel.

10. Fusion reactions require

a. very heavy nuclei. b. incredibly high temperatures.

c. very rare elements for use as fuel. d. no initial energy.

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Answer the following questions.

1. Listed below are six radioisotopes and the isotopes into which they decay. Tell what kind of radioactive decay takes place in each case.

2. The five equations below represent nuclear fission and nuclear fusion reactions. For each equation, tell whether fission or fusion has occurred and write the missing term in the equation.

3. Manganese-55 is bombarded with alpha particles. The nuclear equation for one possible transmutation reaction is shown below. Complete the other four possible transmutation reactions, given one of the reaction products.

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Thinking Critically

The graph below shows the trends in mass defect per nucleon for isotopes across the periodic table. The vertical axis shows the relative stability of an isotope on a scale from 1 to 10, 10 being the most stable. Answer the questions below about this graph.

1. What is the least stable of the isotopes shown on the graph? ___________________

2. What is the most stable of the isotopes shown on the graph? ___________________

3. What is the relative stability of an isotope of mass number 20?

4. Based on this graph, where are the least stable isotopes likely to be found in the periodic table?

5. Explain why isotopes near the beginning of the periodic table become more stable when they undergo nuclear fusion.

6. Explain why isotopes near the end of the periodic table become more stable when they undergo nuclear fission.

Applying Scientific Methods

The table below shows the results of an analysis done on a recently discovered rock. Answer the following questions about the data in the table.

Radioisotope Decay

Scheme Half-life Predicted Order of Abundance

Thorium-232 Alpha emission 1.4 × 1010 years

Radium-228 Beta emission 6.7 years

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Actinium-228 Beta emission 6 hours

Thorium-228 Alpha emission 1.9 years

Radium-224 Alpha emission 3.6 days

1. Write a nuclear equation for the decay process each radioisotope in the table undergoes.

2. In column 4 of the table, indicate the order of abundance of the radioisotopes. Mark the most abundant isotope 1, the second most abundant isotope 2, and so on.

3. Explain how you made the decision in question 2.

A cloud chamber is a detection device in which a condensation track is formed when ionizing radiation passes through a saturated vapor. The diagram is a representation of a view seen in a cloud chamber. In this diagram, various forms of radiation are given off by a radioactive source (X in the diagram). The upper electric plate is positively charged (+) and the lower electric plate is negatively charged (−). In the spaces provided, identify the four types of radiation shown in this diagram and tell how you decided on each answer.

4. Radiation A is ____________________ because

5. Radiation B is ____________________ because

6. Radiation C is ____________________ because

7. Radiation D is ____________________ because