Basic Concepts of Chemical Bonding Test (Answer Key Part 1)

The Central Science Basic Concepts of Chemical Bonding Multiple-Choice Questions 1) Which of the following has eight valence electrons? A) Ti4+ B) Kr C) ClD) Na+ E) all of the above Answer: E 2) Which of the following does not have eight valence electrons? A) Ca+ B) Rb+ C) Xe D) BrE) All of the above have eight valence electrons. Answer: A 3) Lattice energy is ________. A) the energy required to convert a mole of ionic solid into its constituent ions in the gas phase B) the energy given off when gaseous ions combine to form one mole of an ionic solid C) the energy required to produce one mole of an ionic compound from its constituent elements in their standard states D) the sum of ionization energies of the components in an ionic solid E) the sum of electron affinities of the components in an ionic solid Answer: A 4) In ionic bond formation, the lattice energy of ions ________ as the magnitude of the ion charges ________ and the radii ________. A) increases, decrease, increase B) increases, increase, increase C) decreases, increase, increase D) increases, increase, decrease E) increases, decrease, decrease Answer: D The diagram below is the Born-Huber cycle for the formation of crystalline potassium fluoride. 5) Which energy change corresponds to the electron affinity of fluorine? A) 2 B) 5 C) 4 D) 1 E) 6 Answer: C 6) Which energy change corresponds to the first ionization energy of potassium? A) 2 B) 5 C) 4 D) 3 E) 6 Answer: D 7) Using the Born-Haber cycle, the ΔH°f of KBr is equal to ________. A) ΔH°f [K (g)] + ΔH°f [Br (g)] + I1(K) + E(Br) + ΔHlattice B) ΔH°f [K (g)] - ΔH°f [Br (g)] - I1(K) - E(Br) - ΔHlattice C) ΔH°f [K (g)] - ΔH°f [Br (g)] + I1(K) - E(Br) + ΔHlattice D) ΔH°f [K (g)] + ΔH°f [Br (g)] - I1 - E(Br) + ΔHlattice E) ΔH°f [K (g)] + ΔH°f [Br (g)] + I1(K) + E(Br) - ΔHlattice Answer: E 8) The type of compound that is most likely to contain a covalent bond is ________. A) one that is composed of a metal from the far left of the periodic table and a nonmetal from the far right of the periodic table B) a solid metal C) one that is composed of only nonmetals D) held together by the electrostatic forces between oppositely charged ions E) There is no general rule to predict covalency in bonds. Answer: C 9) In which of the molecules below is the carbon-carbon distance the shortest? A) H2C CH2 B) H-C≡C-H C) H3C-CH3 D) H2C C CH2 E) H3C-CH2-CH3 Answer: B 10) Of the molecules below, the bond in ________ is the most polar. A) HBr B) HI C) HCl D) HF E) H2 Answer: D 11) Which of the following has the bonds correctly arranged in order of increasing polarity? A) Be—F, Mg—F, N—F, O—F B) O—F, N—F, Be—F, Mg—F C) O—F, Be—F, Mg—F, N—F D) N—F, Be—F, Mg—F, O—F E) Mg—F, Be—F, N—F, O—F Answer: B 12) Which of the following bonds would be considered non-polar covalent? A) N-H B) C-H C) O-H D) C-Cl E) C-O Answer: B 13) The Lewis structure of N2H2 shows ________. A) a nitrogen-nitrogen triple bond B) a nitrogen-nitrogen single bond C) each nitrogen has one nonbonding electron pair D) each nitrogen has two nonbonding electron pairs E) each hydrogen has one nonbonding electron pair Answer: C 14) The Lewis structure of the CO32- ion is ________. A) B) C) D) E) Answer: A 15) How many electrons are in the Lewis structure of a nitrite ion (NO2-)? A) 18 B) 17 C) 16 D) 23 E) 24 Answer: A 16) Resonance structures differ by ________. A) number and placement of electrons B) number of electrons only C) placement of atoms only D) number of atoms only E) placement of electrons only Answer: E 17) The oxidation number of iron in Fe2O3 is ________. A) -2 B) +1 C) +3 D) +2 E) -3 Answer: C 18) To convert from one resonance structure to another, ________. A) only atoms can be moved B) electrons and atoms can both be moved C) only electrons can be moved D) neither electrons nor atoms can be moved E) electrons must be added Answer: C 19) For ________ forms of a molecule or ion, the observed structure is an average of the ________ forms. A) resonance, covalent B) resonance, resonance C) ionic, resonance D) resonance, ionic E) resonance, metallic Answer: B For the questions that follow, consider the BEST Lewis structures of the following oxyanions: (i) NO2- (ii) NO3- (iii) SO32- (iv) SO42- (v) BrO3- 20) There can be two equivalent best resonance structures of ________. A) (i) B) (ii) C) (iii) D) (iv) E) (v) Answer: A 21) There can be three equivalent best resonance structures of ________. A) (ii), (iii), and (v) B) (i) and (ii) C) (iii) and (v) D) (iii), (iv), and (v) E) all Answer: A 22) A valid Lewis structure of ________ cannot be drawn without violating the octet rule. A) NF3 B) IF3 C) PF3 D) SbF3 E) SO42Answer: B 23) Based on the octet rule, boron will most likely form a ________ ion. A) B3B) B+ C) B3+ D) B2+ E) B2Answer: C 24) Which of the following does not have eight valence electrons? A) ClB) Xe C) Ti+4 D) Rb+ E) Sr+ Answer: E 25) Which of the following Lewis structures would be an expansion to the octet rule? A) SiF4 B) CF4 C) CCl4 D) PO43E) NF3 Answer: D 26) The central atom in ________ does not violate the octet rule. A) SF4 B) KrF2 C) CF4 D) XeF4 E) ICl4Answer: C 27) Which of the following Lewis structures would be an expansion to the octet rule? A) PH3 B) PCl3 C) CCl4 D) CO2 E) SO3 Answer: E 28) A valid Lewis structure of ________ cannot be drawn without violating the octet rule. A) NI3 B) SO2 C) ICl5 D) SiF4 E) CO2 Answer: C 29) Which of the following Lewis structures would be an incomplete octet? A) NF3 B) SO2 C) BCl3 D) CF4 E) SO32Answer: C 30) Why don't we draw double bonds between the Be atom and the Cl atoms in BeCl2? A) That would give positive formal charges to the chlorine atoms and a negative formal charge to the beryllium atom. B) There aren't enough electrons. C) That would result in more than eight electrons around beryllium. D) That would result in more than eight electrons around each chlorine atom. E) That would result in the formal charges not adding up to zero. Answer: A 31) Which of the following atoms may have an expansion to the octet? A) P B) C C) H D) O E) B Answer: A 32) Bond enthalpy is ________. A) always positive B) always negative C) sometimes positive, sometimes negative D) always zero E) unpredictable Answer: A 33) Given that the average bond energies for C-H and C-Br bonds are 413 and 276 kJ/mol, respectively, the heat of atomization of bromoform (CHBr3) is ________ kJ/mol. A) 1241 B) 689 C) -689 D) 1378 E) -1378 Answer: A