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Name______________________________________________ Date______________________ Class_____________________

The Structure of the Atom

Section 4.1 Early Ideas About MatterIn your textbook, read about the philosophers, John Dalton, and defining the atom.

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.

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Name ______________________________________________ Date _____________________ Class _____________________

Section 4.2 Defining the AtomIn your textbook, read about the electron and the nuclear 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

In your textbook, read about the discovery of protons and neutrons.

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

Particle Symbol Location Relative Charge Relative Mass

6. Proton

7. n

8. 1/1840

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Name______________________________________________ Date______________________ Class_____________________

Section 4.3 How Atoms DifferIn your textbook, read about atomic number.

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?______________________________________________________________________________________________

In your textbook, read about isotopes and mass number.

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.______________________________________________________________________________________________

Section 4.3 continued16. An isotope has an atomic number 51 and a mass number 123.

______________________________________________________________________________________________

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 ______________ 20. cesium-133 ______________

19. helium ______________ 21. uranium-234 _______________

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

22. ___________________

23. ___________________

In your textbook, read about mass of individual atoms.

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

24. The mass of an electron isa. 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.

25. One atomic mass unit isa. 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.

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

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Section 4.3 continued

Use the figures to answer the following questions.

27. What is the atomic number of osmium? _____________________

28. What is the chemical symbol for niobium? _______________________

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.

32.Isotope Mass (amu) Percent Abundance

63X 62.930 69.1765X 64.928 30.83

33.Isotope Mass (amu) Percent Abundance

35X 34.969 75.7737X 36.966 24.23

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Section 4.4 Unstable Nuclei and Radioactive DecayIn your textbook, read about radioactivity.

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

In your textbook, read about types of radiation.

Use the diagram to answer the questions.

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

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) Charge8. Alpha9. 1/1840

10. High-energy electromagnetic radiation

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TEACHER GUIDE AND ANSWERS

Study Guide – Chapter 4 – The Structure of the Atom

Section 4.1 Early Ideas About Matter1. false2. true3. true4. true5. false6. false7. true8. true9. false

10. true

Section 4.2 Defining the Atom1. c2. a3. b4. Drawing should look like a ball of chocolate chip

cookie dough. The chocolate chips should be labeled with negative charge or as electrons. The dough should be labeled as evenly distributed positive charges.

5. Drawing should look like a peach with a pit. The pit should be labeled nucleus and should include labeled protons and neutrons. The outer circle of the peach should be labeled electrons.

Particle Symbol Location Relative Charge

Relative mass

6. Proton p In the nucleus 1 1

7. Neutron n0 In the nucleus 0 1

8. Electron e In the space surrounding the nucleus

1 1/1840

Section 4.3 How Atoms Differ1. false2. true3. true4. true5. false6. 82 protons; 82 electrons7. 8 protons

8. 309. 85

10. 104 protons; 104 electrons11. 84 protons; 84 electrons12. 102 protons; 102 electrons13. 19 protons, 19 electrons, 20neutrons14. 14 protons, 14 electrons, 14 neutrons15. 19 protons, 19 electrons, 21 neutrons16. 51 protons, 51 electrons, 72 neutrons17. The two isotopes with atomic number 19 are both

isotopes of potassium.

18.

19.

20.

21.22. mass number23. atomic number24. d25. a26. d27. 7628. Nb29. 190.230. atomic mass units31. osmium: 76 protons, 76 electrons; niobium:

41 protons, 41 electrons.32. Mass contribution (mass)(percent abundance)

63X: (62.930 amu)(69.17%) 43.53 amu65X: (64.928 amu)(30.83%) 20.02 amuAtomic mass of X 43.53 amu 20.02 amu 63.55 amuThe element is copper.

33. Mass contribution (mass)(percent abundance)35X: (34.969 amu)(75.77%) 26.50 amu37X: (36.966 amu)(24.23%) 8.957 amuAtomic mass of X 26.50 amu 8.957 amu 35.46 amuThe element is chlorine.

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TEACHER GUIDE AND ANSWERS

Section 4.4 Changes to the Nucleus—Nuclear Reactions1. c2. a3. d4. b5. the positive plate, because beta particles are

negatively charged6. Gamma rays have no charge.7. The beta particles have less mass than the alpha

particles and ar more greatly affected by the electric field.

Radiation Type

Composition Symbol

Mass(amu)

Charge

8. AlphaHelium nuclei, or alpha particles

4 2

9. Beta Electrons, beta particles

1/1840 1

10. Gamma

High-energy electromagnetic radiation

0 0

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