Chemistry AUnit 2 (Ch4, 25) Study Guide

Answer on a separate sheet of paper and round calculations appropriately.

Chemistry content standards addressed in this unit: 1a. Know how the position of an element in the periodic table relates to its atomic number and atomic mass; 1e. Know the nucleus of the atom is smaller than the atom yet contains most of its mass; 1f. Know transuranium elements are all synthesized in particle accelerators and know how to identify lanthanide, actinide and transactinide elements on the periodic table; 1h. Know the experimental basis for the electron, nucleus and charge of an electron; 11a. Know protons and neutrons are held together by nuclear forces that overcome the natural repulsion of the protons; 11b. Know that the energy released per gram of matter is much larger in nuclear reactions than in chemical reactions; 11c. Know what isotopes are and that some are radioactive; 11d. Know the three most common forms of radioactive decay; 11e. Know how radiation can harm living things and how the three main forms differ in penetrating power; I.f. Distinguish between hypothesis and theory as scientific terms; I.g. Recognize the usefulness and limitations of models and theories as scientific representations of reality; I.k. Recognize the cumulative nature of scientific evidence

I.Introductory Concepts

1. Who is Democritus and what is his contribution?

2. Who is John Dalton, what is his contribution?

3. What are the main points of Dalton’s Atomic Theory?

4. What is the size range of most atoms?

5. What are three benefits to being able to observe and manipulate individual atoms? What is this technology called?

II.Structure of the Atom

6. Make a table to describe the three primary subatomic particles. Where are they found? What are their relative sizes and masses? What are their charges?

7. What two conclusionsresulted from J.J. Thomson’s Cathode Ray experiment?

8. What are the “four simple ideas about matter and electrical charge?”

9. Describe the “Plum Pudding Model” of the atom? Whose idea was it?

10. Describe Rutherford’s Gold Foil experiment: what was involved and what happened.

11. What was the resulting conclusion from Rutherford’s experiment?

III.Distinguishing Among Atoms

12. What makes different elements different?

13. Define Atomic Number. Which symbol represents atomic number: A, X, Y or Z? How do you find the atomic number of a given element?

14. Define Mass Number. Which symbol represents mass number: A, X, Y or Z?

15. Define Isotope. What do isotopes of the same element have in common? What is different?

16. The atomic number of magnesium is 12. What kind and how many particles must its nucleus contain?

17. How might neutral atoms of the same element differ?

18. An element has an atomic number of 4 and a mass number of 9. How many neutrons are found in thenucleus of an atom of this element?

19. What is an amu? Why is it a useful unit?

20. What is meant by the term: percent isotopic abundance (or just isotope abundance)?

21. How is the atomic mass of an element calculated?

22. How does an atom of carbon whose mass number is 14 differ from an atom of carbon whose mass number is 12?

23. Sketch an outline of the periodic table and identify the following: metals, semimetals, nonmetals, period and group.

24. What is the charge of an atom’s nucleus?

25. How do neutrons affect an atom’s atomic number and mass number?

26. Draw the nuclide symbol of gold-197. If this atom loses 3 electrons, how many remain? What is the atom’s charge?

IV.Nuclear Radiation

27. Define nuclear radiation and radioactive decay.

28. What are the three main types of nuclear radiation? What Greek letters are associated with these processes? Which are particles? Which is the lightest? Which is most massive? How are they affected by an electric field? Rank in order of increasing penetrating power.

29. Write a balanced nuclear equation that illustrates alpha decay of Pa-231.

30. Write a balanced nuclear equation that illustrates beta negative decay of C-14.

31. What happens to A as a result of beta decay?

32. What happens to Z as a result of beta decay?

33. By which common decay mode does an atom lose the greatest mass? The least?

V. Nuclear Stability, Half-Life, Reactions and Health Considerations

34. What force holds protons together in the nucleus?

35. Define Half-Life. How is it useful?

36. A piece of wood found in an ancient burial chamber contains only half as much C-14 as a piece of wood cut from a living tree nearby. If the half-life of C-14 is 5730 years, what is the approximate age of the ancient wood?

37. Define Transmutation; by what two ways can nuclear transmutation occur?

38. Write the balanced nuclear equation for the union of an alpha particle with a nitrogen-14 atom to produce a proton and one other atom.

39. Compare and contrast nuclear fission and nuclear fusion.

40. What is the most common substance used as a moderator in nuclear reactors?

41. How is radiation detected?

42. Define Ionizing Radiation. Why is this potentially harmful to living things (like us)?

43. What are two major health risks involved with nuclear radiation?

44. Describe three useful applications of radiation.

45. There are four naturally occurring isotopes of the element chromium. The relative abundance of each is: Cr-50 = 4.31%, Cr-52 = 83.76%, Cr-53 = 9.55%, Cr-54 = 2.38%. Calculate the average atomic mass of chromium.