2. What is a molecule? 3. What is an element? 4. What is a compound? 5. What is

2. What is a molecule? 3. What is an element? 4. What is a compound? 5. What is the chemical symbol for oxygen? 6. What is the chemical symbol for sodium? 7. What is the chemical symbol for nitrogen? 8. What is the chemical symbol for potassium? 9. What is the chemical symbol for chlorine? 10. What is the chemical symbol for carbon? 11. How many atoms are present in one molecule of water (H2O) ? 12. How many atoms are present in one molecule of glucose (C6H12O6) ? 13. How many molecules of carbon dioxide are indicated by : 8CO2 ? 14. How many atoms are present in 8CaCl2 ? 15. What type of electrical charge is present on a proton? 16. In what part of an atom are protons located? 17. Define: atomic number (AN) 18. What is the atomic number of carbon? hydrogen? oxygen? 19. If a carbon atom gains a proton will the atom still have the properties of carbon? 20. True or False Each oxygen atom has 8 protons. 21. What is the electrical charge on an electron? 22. In what part of an atom are electrons located? 23. How many electrons are present in an atom? 24. Define: mass number (= atomic weight AW) 25. Helium (He) has 2 protons and 2 neutrons; what is the (a) atomic number and (b) the mass number of helium? 26. Fluorine (F) has an atomic number of 9 and contains 10 neutrons in each atom. (a) What is the mass number of fluorine? (b) How many protons are present in one atom of fluorine? (c) How many electrons are present in one atom of fluorine before it reacts with other atoms? 27. Sulfur (S) has an atomic number of 16 and a mass number of 32. How many protons neutrons and electrons are present in one atom? 28. An atom of aluminum (Al) contains 13 protons and has a mass number of 27; how many protons neutrons and electrons are present in one atom? 29. True or False All electrons contain the same amount of energy. 30. How many electrons can the first (i.e. the inner) shell of an atom hold? 31. How many electrons can the second shell of an atom hold? 32. How many electrons can the outer shell of an atom hold? 33. Which shell has electrons with the lowest amount of energy? 34. Which shell has electrons with the highest amount of energy? 35. What happens to the energy level of an electron as it moves from the second shell to the third shell? 36. What happens to the energy level of an electron as it moves from the fourth shell to the third shell? 37. How many electrons and protons are present in an atom that is electrically neutral? 38. How does an atom become stable? 39. Which will an atom attempt to do: become neutral or become stable ? 40. Chlorine (Cl) has an atomic number of 17. How many protons does it possess? How many electrons does it possess? How many electrons are present in its first shell? in its second shell? in its third shell? 41. Is chlorine stable when it has 17 electrons? if not explain why. 42. Define: ion 43. Sodium (Na) has an atomic number of 11. How many protons does it possess? How many electrons does it possess? How many electrons are in its first shell? in its second shell? in its third shell? 44. Is sodium (Na) stable with 11 electrons? If not explain why. 45. Name an example of an ion with a negative charge on it. Explain why it has a negative charge. 46. Name an example of an ion with a positive charge on it. Explain why it has a positive charge. 47. What happens when two ions with the same type of charge (i.e. both ions are either positive or negative) come near each other? 48. What happens when two ions with opposite charges (i.e. one is negative and one is positive) come near each other? 49. Define: ionic bond 50. Why is an oxygen atom with 8 electrons not stable? 51. How can an oxygen atom with 8 electrons become stable? 52. Why is a hydrogen atom with 1 electron not stable? 53. How can a hydrogen atom with 1 electron become stable? 54. Explain how one atom of oxygen and two atoms of hydrogen can bond with each other and result in all three atoms becoming stable. 55. Define: covalent bonding 56. Explain why ammonia (NH3) is stable (N has an atomic number = 7) 57. Why is NH4 not stable? 58. In a water molecule are the electrons shared evenly between the oxygen and hydrogen atoms? Explain your answer. 59. Define: polarized molecule 60. Name an example of a molecule that is covalently bonded but is not polarized. Why is this molecule not polarized? 61. Is a water molecule polarized? Why? 62. How do two water molecules react with each other when they are close together? 63. Define: hydrogen bond 64. Name an example of two molecules that are held together by hydrogen bonding. 65. Define: cohesion 66. Define: adhesion 67. Considering the energy levels of the reactants and the energy levels of the products of reactions name two types of chemical reactions. 68. Define: catalyst 69. After the completion of a chemical reaction involving a catalyst how much of the catalyst remains? 70. Define: enzyme 71. True or False All catalysts are enzymes. 72. True or False All enzymes are catalysts. 73. True or False All enzymes are composed of proteins. 74. True or False Proteins are used only as enzymes. 75. What three letters are present at the end of the name of most enzymes?