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Honors Chemistry Midterm Extra Practice 1. The factor being tested in an experiment is called the a. hypothesis b. observation c. natural law d. variable 2. Density is equal to a. mass/volume b. mass – volume c. volume/mass d. mass + volume 3. Which state of matter is characterized by definite shape and definite volume? a. solid b. liquid c. gas d. plasma 4. Which of the following is an example of a heterogeneous mixture? a. sand in water b. homogenized milk c. salt dissolved in water d. air 5. What is the charge on an alpha particle? a. 2+ b. 1+ c. 1d. 0 6. An element’s identity is based on its a. atomic mass b. mass number c. number of neutrons d. atomic number 7. Which of the following describes a beta particle? a. atomic number = 1, mass number = 0 b. atomic number = -1, mass number = 1 c. atomic number = 0, mass number = 0 d. atomic number = -1, mass number = 0 8. The beta decay of rubidium-87 produces a. krypton-87 b. strontium-87 c. bromine-83 d. rubidium-86 9. Light has the properties of a. particles only b. waves only c. both particles and waves d. neither particles nor waves 10. Which of the following has the longest wavelength? a. ultraviolet radiation b. infrared radiation c. X-rays d. gamma rays 11. The probability of finding electrons in certain regions of an atom is described by a. orbits b. orbitals c. quanta d. photons 12. How many periods are in the periodic table? a. 7 b. 8 c. 18 d. 109 13. The elements in group 18 (8A) of the periodic table are called a. halogens b. alkali metals c. alkaline earth metals d. noble gases 14. Atomic radius is the distance from a. the center of an atomic nucleus to its outermost electron b. one edge of an atom to another atom c. one atom to the next atom d. the center of an atom’s nucleus to the center of an adjacent atom’s nucleus 15. When an atom becomes an anion, it a. loses protons b. remains the same size c. becomes larger d. becomes smaller 16. An example of an actinide element is a. radium b. iridium c. thorium d. cerium 17. The physical state of nearly all ionic compounds at room temperature is a. solid b. liquid c. gas d. different for each ionic compound 18. For the element whose electron configuration is [Ne] 3s23p3, how many dots would the Lewis dot diagram have? a. 3 b. 5 c. 8 d. 13 19. For the diatomic molecule Cl2, how many electron(s) does each chlorine atom share with the other chlorine atom so that each has an octet? a. 1 b. 2 c. 7 d. 8 20. In the compound ammonia, a. each hydrogen has a partial negative charge b. the nitrogen has a full positive charge c. the N-H bond is an ionic bond d. the Lewis structure will have one unshared pair of electrons 21. What is the name of the compound whose formula is FeSO4? a. iron (II) sulfate b. iron (II) sulfide c. iron (III) sulfate d. iron (III) sulfide 22. What is the formula of the compound formed between calcium and hydroxide ions? a. CaOH b. Ca(OH)2 c. CaOH2 d. Ca2OH 23. What is the formula of iron (III) nitrate? a. Fe(NO3)3 b. FeN c. Fe3NO3 d. none of these is correct Element F O Cl Br C H P B Mg Ca Na K Electronegativity 4.0 3.5 3.0 2.8 2.5 2.1 2.1 2.0 1.2 1.0 0.9 0.8 24. Using the figure above, what kind of bond would be formed between potassium and bromine? a. nonpolar covalent b. polar covalent c. ionic d. intermolecular covalent 25. What shape does an ammonia molecule have? a. pyramidal b. trigonal planar c. tetrahedral d. bent 26. The shape of a methane molecule (CH4) is a. pyramidal b. trigonal planar c. tetrahedral d. pyramidal 27. The methane molecule (CH4) has a bond angle of a. 107° b. 109.5° c. 120° d. 180° 28. How many unshared pairs of valence electrons does the central atom in a bent molecule have? a. none b. one c. two d. three 29. What determines the polarity of a bond? a. electronegativity difference only b. molecular shape only c. both a and b d. neither a nor b 30. Which of the following is true of a water molecule? a. the hydrogen end is slightly positive and the oxygen end is slightly negative b. the hydrogen end is slightly negative and the oxygen end is slightly positive c. the oxygen atom has a 2- charge and each hydrogen atom has a 1+ charge d. it has neither a positive nor a negative end 31. Which of the following is NOT an example of a chemical change? a. rusting iron b. an apple ripening c. cutting paper d. a piece of wood burning 32. A tentative or suggested answer to a question, formulated before experimentation, is called a(n) a. natural law b. observation c. hypothesis d. theory 33. In multiplication and division of measured values, the measured value that determines the number of significant digits in the answer is the one that has the a. largest number of significant digits b. smallest number of significant digits c. largest number of decimal places d. smallest number of significant zeros 34. What is absolute zero? a. zero degrees on the Celsius scale b. the point at which the potential energy of particles is zero c. the point at which the motion of particles ceases d. the temperature at which water freezes 35. A substance that cannot be separated into simpler substances by a chemical change is called a(n) a. compound b. mixture c. element d. crystal 36. Which of the following statements is part of Dalton’s atomic theory of matter? a. all atoms are identical b. all atoms of a given element are identical c. all atoms differ from on another d. all atoms of a given element have the same mass 37. The mass number of an atom is defined as its a. mass in amu b. number of protons c. total number of protons and electrons d. total number of neutrons and protons 38. The atom fluorine-19 contains a. 19 protons and 9 neutrons b. 9 protons and 10 neutrons c. 9 protons and 19 neutrons d. 9 protons and 10 electrons 39. The joining of two small nuclei to form a larger nucleus is called a. nuclear fission b. nuclear fusion c. neutron capture d. radioactive decay 40. Which color of visible light has the highest frequency? a. blue b. red c. yellow d. violet 41. Quanta of light are called a. electrons b. protons c. photons d. joules 42. The principle that states that electrons are added one at a time to the lowest-energy orbitals available until all electrons have been accounted for is a. the Aufbau principle b. the Pauli exclusion principle c. the uncertainty principle d. Hund’s rule 43. In the periodic table, the periods are the a. vertical columns b. horizontal rows c. chemical families d. blocks of elements 44. What are the elements of in group 17 (7A) called? a. halogens b. alkali metals c. alkaline earth metals d. noble gases 45. The valence electrons in an atom are always a. inside the nucleus b. the innermost electrons c. the outermost electrons d. in s orbitals 46. What is an atom’s ionization energy? a. the energy given off when an electron is gained b. the energy needed to gain an electron c. the energy given off when an electron is lost d. the energy needed to remove an electron 47. An example of a lanthanide element is a. radium b. iridium c. thorium d. cerium 48. When a calcium atom becomes an ion, it a. gains one proton b. gains two electrons c. loses one electron d. loses two electrons 49. In an ionic bond, how does a nitrogen atom most commonly achieve an octet of electrons? a. by gaining 5 electrons b. by gaining 3 electrons c. by losing 5 electrons d. by losing 3 electrons 50. How does a covalent bond differ from an ionic bond? a. an ionic bond is the transfer of electrons and covalent is a sharing of electrons b. an ionic bond involves 2 electrons and a covalent bond involves 4 electrons c. an ionic bond is usually between two metals and a covalent bond is usually between two nonmetals d. ionic bonds are usually found in acids and covalent bonds are usually found in bases 51. Which of the following bonds is primarily covalent? a. O-N b. Na-S c. O-K d. Cl-Li 52. What is the name of the compound whose formula is (NH4)3PO4? a. triammonium quatrophosphate b. polyammonium phosphate c. ammonium phosphate d. none of these is correct 53. The anion from which H2CO3 gets its name is a. acetate b. carbonate c. chloride d. hydrogen 54. What is the formula of copper (II) chloride? a. CuCl2 b. (CuCl)2 c. CuCl d. Cu2Cl 55. Which theory is used to account for the shape of molecules? a. theory of relativity b. thermodynamic theory c. kinetic theory d. VSEPR theory 56. What shape does a carbon dioxide molecule have? a. linear b. bent c. trigonal planar d. pyramidal 57. In a carbon dioxide molecule, the bond angle is a. 107° b. 109.5° c. 120° d. 180° 58. In a tetrahedral molecule, how many unshared pairs of valence electrons does the central atom have? a. none b. one c. two d. three 59. Dipoles are a. nonpolar bonds b. polar bonds c. nonpolar molecules d. polar molecules 60. How would you describe a molecule of carbon dioxide? a. nonpolar, with nonpolar bonds b. nonpolar, with polar bonds c. polar, with nonpolar bonds d. polar, with polar bonds 61. Which of the following is a physical change? a. cooking b. burning c. rusting d. crushing 62. Which of the following is a prefix that makes the unit larger? a. kilo- b. decic. millid. pico63. What is the SI unit of temperature? a. Celsius b. Farenheit c. Kelvin d. Roentgen 64. Which of the following is a physical property? a. flammability b. density c. tendency to rust d. none of the above 65. Which of the following is an example of a homogeneous mixture? a. oil and water b. salt and pepper c. sawdust and nails d. seawater 66. Which of the following particles is normally found outside the nucleus of an atom? a. electron b. proton c. neutron d. alpha particle 67. An ion always contains an a. unequal number of protons and electrons b. equal number of protons and electrons c. unequal number of protons and neutrons d. equal number of protons and neutrons 68. Which of the following describes an alpha particle? a. atomic number = 4, mass number = 2 b. atomic number = 2, mass number = 4 c. atomic number = 4, mass number = 4 d. atomic number = 2, mass number = 0 69. The half-life of a sample of a radioactive isotope is the time required for half of it to a. become stable b. undergo fission c. decay d. undergo oxidation 70. Which wave property expresses how often a wave oscillates up and down? a. frequency b. amplitude c. wavelength d. speed 71. Quanta are fundamental “pieces” of a. energy b. matter c. nuclei d. electrons 72. Under what conditions can two electrons occupy the same orbital? a. never b. if they have opposite spins c. if they have parallel spins d. if they have different principal quantum numbers 73. The relationship in which the physical and chemical properties of elements show a periodic pattern when the elements are arranged by increasing atomic number is called a. the periodic law b. the law of octaves c. Mendeleev’s law d. Meyer’s periodicity 74. The elements in group 1 (1A) of the periodic table are called the a. halogens b. alkali metals c. alkaline earth metals d. noble gases 75. Malleability is characteristic of a. all elements b. semimetals c. nonmetals d. metals 76. As you move down a group on the periodic table, the atomic radii of the elements a. increase b. decrease c. remain constant d. show no pattern 77. Electronegativity is the ability of an atom to a. release electrons b. become an ion c. conduct an electric current d. attract electrons in a chemical bond 78. A positively charged ion a. is formed when an atom loses electrons b. is called an anion c. is usually a nonmetallic element d. has more electrons than protons 79. Ionic compounds are normally a. good conductors of electricity in the solid state b. gases at room temperature c. formed when a metal transfers its valence electrons to a nonmetal d. electrically charged 80. The formulas of the oxide and nitrate ions are respectively a. O2- and NO3b. OH- and NO42c. O2- and NH4+ d. O and NO3 81. How many pairs of shared and unshared electrons does the Lewis dot structure for water have? a. 4, 0 b. 3, 1 c. 2, 2 d. 4, 4 82. A bond is classified as nonpolar covalent if the difference in electronegativities between the two atoms is a. 2.1 or more b. between 0.5 and 2.0 c. less than 0.4 d. less than 0 83. What is the name of the compound whose formula is NaC2H3O2 ∙ 9H2O? a. sodium carbonate hydrate b. sodium acetate nonahydrate c. sodium acetate hydrate d. sodium carbonate nonahydrate 84. What is the formula of the compound formed between calcium and sulfate ions? a. CaS b. Ca2(SO4)2 c. Ca2S2 d. CaSO4 85. What is the formula of sulfuric acid? a. HS b. H2S c. H2SO4 d. HSO4 86. Using the figure above, which two elements would form the most ionic bond possible? a. F-F b. F-O c. Ca-O d. K-F 87. What shape does a boron trichloride molecule have? a. pyramidal b. trigonal planar c. tetrahedral d. bent 88. What is the bond angle in a molecule of ammonia? a. 107° b. 109.5° c. 120° d. 180° 89. What is the bond angle of a water molecule? a. 90° b. 105° c. 107° d. 109.5° 90. How do the lengths of single, double, and triple bonds between the same kinds of atoms compare? a. they are all equal b. single bonds are longest c. double bonds are longest d. triple bonds are longest 91. What determines the polarity of a molecule? a. electronegativity difference only b. molecular shape only c. both a and b d. neither a nor b 92. Which of the following is NOT an example of a chemical change? a. rusting iron b. an apple ripening c. cutting paper d. a piece of wood burning 93. Chemistry is best defined as the study of a. the structure of matter b. all substances and the changes they can undergo c. the substances found on the periodic table and the compounds they can form d. what happens when two elements are mixed together 94. In which of the following is the zero not significant? a. 1.050 b. 1.05 c. 1.50 d. 1050 95. What is the SI unit of energy? a. joule b. degree Farenheit c. Kelvin d. calorie 96. Which of the following is a physical change? a. cooking b. burning c. rusting d. crushing 97. An atom is defined as the smallest part of an element that a. contains at least one proton, neutron, and electron b. retains the chemical identity of that element c. can carry an electric charge d. is affected by a cathode ray tube 98. The atomic number of an atom is defined as its a. mass in amu b. number of electrons c. number of neutrons d. number of protons 99. Two atoms are isotopes if they contain a. different numbers of electrons b. different numbers of protons and different numbers of neutrons c. the same number of protons but different numbers of neutrons d. the same number of neutrons but different numbers of protons 100. An alpha particle is the same as a(n) a. helium nucleus b. deuterium nucleus c. electron d. neutron 101. The splitting of a large nucleus into two smaller nuclei of approximately equal size is called a. nuclear fission b. nuclear fusion c. neutron capture d. radioactive decay 102. A hertz is the same as a. 1/second b. 1 second c. 1 centimeter/second d. 1/centimeter 103. The photoelectric effect was explained by a. Einstein b. Planck c. Bohr d. Heisenberg 104. When electrons are in the lowest-energy orbitals available, the atom is a. unstable b. in an excited state c. in the ground state d. chemically unreactive 105. The scientist credited with the first periodic table of elements was a. Mendeleev b. Moseley c. Newlands d. Dobereiner 106. The elements in group 2 (2A) of the periodic table are called the a. halogens b. alkali metals c. alkaline earth metals d. noble gases 107. Those electrons that are largely responsible for an atom’s chemical behavior are called a. core electrons b. valence electrons c. high energy electrons d. stable electrons 108. When an atom loses electrons, it a. collapses b. becomes negatively charged c. becomes smaller d. becomes larger 109. An alloy is a a. highly pure metal b. highly pure nonmetal c. mixture of metals d. mixture of nonmetals 110. When a potassium atom becomes an ion, it a. gains one proton b. gains one electrons c. loses one proton d. loses one electron 111. All of the following atoms have an octet of electrons except a. Al3+ b. Clc. Mg2+ d. O112. Monatomic anions are named with the suffix a. –ate b. –ite c. –ide d. –ade 113. In a double bond between two atoms, the number of shared electrons is a. 2 b. 4 c. 6 d. 8 114. Which of the following bonds would be considered completely nonpolar? a. H-N b. O-O c. O-C d. F-Cl 115. What is the name of the molecular substance PCl5? a. phosphorus chloride b. monophosphorus pentachloride c. phosphorus pentachloride d. all of the above are suitable names 116. What is the formula for aluminum phosphide? a. AlP b. AlPO3 c. Al(PO)4 d. Al3(PO4)3 117. What is the formula of hydrochloric acid? a. HOCl b. HCl c. H2Cl2 d. H2(ClO)2 117. In a molecule of carbon dioxide, what kinds of bonds connect the carbon atom to the two oxygen atoms? a. two single bonds b. one single bond and one double bond c. one double bond and one triple bond d. two double bonds 118. What is the bond angle in a boron trifluoride molecule? a. 107° b. 109.5° c. 120° d. 180° 119. In a pyramidal molecule, how many unshared pairs of valence electrons does the central atom have? a. none b. one c. two d. three 120. In a polar bond, electrons are a. shared unequally b. shared equally c. completely transferred d. not shared at all 121. How are the electrons shared in a bond between carbon and oxygen? a. they are equally shared b. carbon attracts them more c. oxygen attracts them more d. electrons are completely transferred Also, be able to do Lewis dot structures, electron configurations, nuclear equations, conversions, and naming compounds – see the extra practice on the website for extra help. Answers 1. The factor being tested in an experiment is called the d. variable 2. Density is equal to a. mass/volume 3. Which state of matter is characterized by definite shape and definite volume? a. solid 4. Which of the following is an example of a heterogeneous mixture? a. sand in water 5. What is the charge on an alpha particle? a. 2+ 6. An element’s identity is based on its d. atomic number 7. Which of the following describes a beta particle? d. atomic number = -1, mass number = 0 8. The beta decay of rubidium-87 produces b. strontium-87 9. Light has the properties of c. both particles and waves 10. Which of the following has the longest wavelength? b. infrared radiation 11. The probability of finding electrons in certain regions of an atom is described by b. orbitals 12. How many periods are in the periodic table? a. 7 13. The elements in group 18 (8A) of the periodic table are called d. noble gases 14. Atomic radius is the distance from a. the center of an atomic nucleus to its outermost electron 15. When an atom becomes an anion, it c. becomes larger 16. An example of an actinide element is c. thorium 17. The physical state of nearly all ionic compounds at room temperature is a. solid 18. For the element whose electron configuration is [Ne] 3s23p3, how many dots would the Lewis dot diagram have? b. 5 19. For the diatomic molecule Cl2, how many electron(s) does each chlorine atom share with the other chlorine atom so that each has an octet? a. 1 20. In the compound ammonia, d. the Lewis structure will have one unshared pair of electrons 21. What is the name of the compound whose formula is FeSO 4? a. iron (II) sulfate 22. What is the formula of the compound formed between calcium and hydroxide ions? b. Ca(OH)2 23. What is the formula of iron (III) nitrate? a. Fe(NO3)3 Element F O Cl Br C H P B Mg Ca Na K Electronegativity 4.0 3.5 3.0 2.8 2.5 2.1 2.1 2.0 1.2 1.0 0.9 0.8 24. Using the figure above, what kind of bond would be formed between potassium and bromine? b. polar covalent 25. What shape does an ammonia molecule have? a. pyramidal 26. The shape of a methane molecule (CH4) is c. tetrahedral 27. The methane molecule (CH4) has a bond angle of b. 109.5° 28. How many unshared pairs of valence electrons does the central atom in a bent molecule have? c. two 29. What determines the polarity of a bond? a. electronegativity difference only 30. Which of the following is true of a water molecule? a. the hydrogen end is slightly positive and the oxygen end is slightly negative 31. Which of the following is NOT an example of a chemical change? c. cutting paper 32. A tentative or suggested answer to a question, formulated before experimentation, is called a(n) c. hypothesis 33. In multiplication and division of measured values, the measured value that determines the number of significant digits in the answer is the one that has the b. smallest number of significant digits 34. What is absolute zero? c. the point at which the motion of particles ceases 35. A substance that cannot be separated into simpler substances by a chemical change is called a(n) c. element 36. Which of the following statements is part of Dalton’s atomic theory of matter? b. all atoms of a given element are identical 37. The mass number of an atom is defined as its d. total number of neutrons and protons 38. The atom fluorine-19 contains b. 9 protons and 10 neutrons 39. The joining of two small nuclei to form a larger nucleus is called b. nuclear fusion 40. Which color of visible light has the highest frequency? d. violet 41. Quanta of light are called c. photons 42. The principle that states that electrons are added one at a time to the lowest-energy orbitals available until all electrons have been accounted for is a. the Aufbau principle 43. In the periodic table, the periods are the b. horizontal rows 44. What are the elements of in group 17 (7A) called? a. halogens 45. The valence electrons in an atom are always c. the outermost electrons 46. What is an atom’s ionization energy? d. the energy needed to remove an electron 47. An example of a lanthanide element is d. cerium 48. When a calcium atom becomes an ion, it d. loses two electrons 49. In an ionic bond, how does a nitrogen atom most commonly achieve an octet of electrons? b. by gaining 3 electrons 50. How does a covalent bond differ from an ionic bond? a. an ionic bond is the transfer of electrons and covalent is a sharing of electrons 51. Which of the following bonds is primarily covalent? a. O-N 52. What is the name of the compound whose formula is (NH 4)3PO4? c. ammonium phosphate 53. The anion from which H2CO3 gets its name is b. carbonate 54. What is the formula of copper (II) chloride? a. CuCl2 55. Which theory is used to account for the shape of molecules? d. VSEPR theory 56. What shape does a carbon dioxide molecule have? a. linear 57. In a carbon dioxide molecule, the bond angle is d. 180° 58. In a tetrahedral molecule, how many unshared pairs of valence electrons does the central atom have? a. none 59. Dipoles are d. polar molecules 60. How would you describe a molecule of carbon dioxide? b. nonpolar, with polar bonds 61. Which of the following is a physical change? d. crushing 62. Which of the following is a prefix that makes the unit larger? a. kilo63. What is the SI unit of temperature? c. Kelvin 64. Which of the following is a physical property? b. density 65. Which of the following is an example of a homogeneous mixture? d. seawater 66. Which of the following particles is normally found outside the nucleus of an atom? a. electron 67. An ion always contains an a. unequal number of protons and electrons 68. Which of the following describes an alpha particle? b. atomic number = 2, mass number = 4 69. The half-life of a sample of a radioactive isotope is the time required for half of it to c. decay 70. Which wave property expresses how often a wave oscillates up and down? a. frequency 71. Quanta are fundamental “pieces” of a. energy 72. Under what conditions can two electrons occupy the same orbital? b. if they have opposite spins 73. The relationship in which the physical and chemical properties of elements show a periodic pattern when the elements are arranged by increasing atomic number is called a. the periodic law 74. The elements in group 1 (1A) of the periodic table are called the b. alkali metals 75. Malleability is characteristic of d. metals 76. As you move down a group on the periodic table, the atomic radii of the elements a. increase 77. Electronegativity is the ability of an atom to d. attract electrons in a chemical bond 78. A positively charged ion a. is formed when an atom loses electrons 79. Ionic compounds are normally c. formed when a metal transfers its valence electrons to a nonmetal 80. The formulas of the oxide and nitrate ions are respectively a. O2- and NO381. How many pairs of shared and unshared electrons does the Lewis dot structure for water have? c. 2, 2 82. A bond is classified as nonpolar covalent if the difference in electronegativities between the two atoms is c. less than 0.4 83. What is the name of the compound whose formula is NaC2H3O2 ∙ 9H2O? b. sodium acetate nonahydrate 84. What is the formula of the compound formed between calcium and sulfate ions? d. CaSO4 85. What is the formula of sulfuric acid? c. H2SO4 86. Using the figure above, which two elements would form the most ionic bond possible? d. K-F 87. What shape does a boron trichloride molecule have? b. trigonal planar 88. What is the bond angle in a molecule of ammonia? a. 107° 89. What is the bond angle of a water molecule? b. 105° 90. How do the lengths of single, double, and triple bonds between the same kinds of atoms compare? b. single bonds are longest 91. What determines the polarity of a molecule? c. both a and b 92. Which of the following is NOT an example of a chemical change? c. cutting paper 93. Chemistry is best defined as the study of b. all substances and the changes they can undergo 94. In which of the following is the zero not significant? d. 1050 95. What is the SI unit of energy? a. joule 96. Which of the following is a physical change? d. crushing 97. An atom is defined as the smallest part of an element that b. retains the chemical identity of that element 98. The atomic number of an atom is defined as its d. number of protons 99. Two atoms are isotopes if they contain c. the same number of protons but different numbers of neutrons 100. An alpha particle is the same as a(n) a. helium nucleus 101. The splitting of a large nucleus into two smaller nuclei of approximately equal size is called a. nuclear fission 102. A hertz is the same as a. 1/second 103. The photoelectric effect was explained by a. Einstein 104. When electrons are in the lowest-energy orbitals available, the atom is c. in the ground state 105. The scientist credited with the first periodic table of elements was a. Mendeleev 106. The elements in group 2 (2A) of the periodic table are called the c. alkaline earth metals 107. Those electrons that are largely responsible for an atom’s chemical behavior are called b. valence electrons 108. When an atom loses electrons, it c. becomes smaller 109. An alloy is a c. mixture of metals 110. When a potassium atom becomes an ion, it d. loses one electron 111. All of the following atoms have an octet of electrons except d. O112. Monatomic anions are named with the suffix c. –ide 113. In a double bond between two atoms, the number of shared electrons is b. 4 114. Which of the following bonds would be considered completely nonpolar? b. O-O 115. What is the name of the molecular substance PCl5? c. phosphorus pentachloride 116. What is the formula for aluminum phosphide? a. AlP 117. What is the formula of hydrochloric acid? b. HCl 117. In a molecule of carbon dioxide, what kinds of bonds connect the carbon atom to the two oxygen atoms? d. two double bonds 118. What is the bond angle in a boron trifluoride molecule? c. 120° 119. In a pyramidal molecule, how many unshared pairs of valence electrons does the central atom have? b. one 120. In a polar bond, electrons are a. shared unequally 121. How are the electrons shared in a bond between carbon and oxygen? c. oxygen attracts them more Also, be able to do Lewis dot structures, electron configurations, nuclear equations, conversions, and naming compounds – see the extra practice on the website for extra help.