CHEMISTRY Practice Exam #4

Transcription

1 CHEMISTRY Practice Exam #4 This is a multiple choice exam. Choose the BEST answer from the choices which are given and write the letter for your choice in the space provided. 1. Which of the following have their valence electrons in the same shell? A) Li, N, F B) B, Si, As C) N, As, Bi D) He, Ne, F 2. Which of the following have the same number of valence electrons? A) Rb, Sb, I B) Ga, Sn, Bi C) As, Sb, Bi D) Ar, Kr, Br 3. Place the following elements in order of decreasing atomic radius. Xe Rb Ar A) Ar > Xe > Rb B) Xe > Rb > Ar C) Ar > Rb > Xe D) Rb > Xe > Ar 4. Choose the statement that is TRUE. A) Outer electrons efficiently shield one another from nuclear charge. B) Core electrons effectively shield outer electrons from nuclear charge. C) Valence electrons are the most difficult of all electrons to remove. D) Core electrons are the easiest of all electrons to remove 5. Choose the diamagnetic species from below. A) Cr!!! B) Br C) P D) Sn2+ 6. The effective nuclear charge experienced by a valence electron is less than the actual nuclear charge due to A) paramagnetism. B) promotion of core electrons to the valence shell. C) shielding of valence electrons by core electrons. D) electron-pair repulsions in the valence shell.

2 7. Identify the compound with covalent bonding. B) Li C) H2O D) He 8. Identify the compound with metallic bonding. B) Li C) H2O D) He 9. Which of the following statements is TRUE? A) A covalent bond has a lower potential energy than the two separate atoms. B) A pair of electrons involved in a covalent bond are sometimes referred to as "lone pairs." C) It is not possible for two atoms to share more than two electrons. D) Single bonds are shorter than double bonds. 10. Which of the following statements is TRUE? A) An ionic bond is much stronger than most covalent bonds. B) An ionic bond is formed through the sharing of electrons. C) Solid ionic compounds at room temperature typically conduct electricity. D)Once dissolved in water, ionic compounds rarely conduct electricity 11. Which of the following reactions is associated with the lattice energy of Li2O (ΔH latt)? A) Li2O(s) 2 Li+(g) + O2 (g) B) 2 Li+(aq) + O2 (aq) Li2O(s) C) 2 Li+(g) + O2 (g) Li2O(s) D) Li2O(s) 2 Li+(aq) + O2 (aq) 12. ) Identify the compound with the highest magnitude of lattice energy. B) KCl C) LiCl D) CsCl

3 13. Identify the number of bonding pairs and lone pairs of electrons in water. A) 1 bonding pair and 1 lone pair B) 1 bonding pair and 2 lone pairs C) 2 bonding pairs and 2 lone pairs D) 2 bonding pairs and 1 lone pair 14. Place the following elements in order of increasing electronegativity. Sr N Na A) Sr < Na < N B) Na < N < Sr C) Sr < N < Na D) N < Sr < Na 15. Choose the best Lewis structure for XeI2. A) B) C) D) 16. Choose the best Lewis structure for SeO4 2. A) B) C) D) 17. Choose the bond below that is the weakest. A) Na-Cl B) I-I C) C=N D) Li-F

4 18. Use the bond energies provided to estimate ΔH rxn for the reaction below. XeF2 + 2 F2 XeF6 ΔH rxn =? Bond Bond Energy (kj/mol) Xe-F 147 F-F 159 A) -429 kj B) +159 kj C) -270 kj D) +176 kj 19. Determine the electron geometry (eg) and molecular geometry (mg) of CO3 2. B) eg=tetrahedral, mg=trigonal pyramidal D) eg=trigonal planar, mg=trigonal planar 20. Determine the electron geometry (eg) and molecular geometry (mg) of CH3 +1. B) eg=tetrahedral, mg=trigonal pyramidal D) eg=trigonal planar, mg=trigonal planar 21. Determine the electron geometry (eg) and molecular geometry (mg) of NCl3. B) eg=linear, mg=trigonal planar D) eg=tetrahedral, mg=trigonal pyramidal 22. Consider the molecule below. Determine the molecular geometry at each of the 3 labeled atoms. A) 1=trigonal planar, 2=tetrahedral, 3=trigonal pyramidal B) 1=tetrahedral, 2=tetrahedral, 3=tetrahedral C) 1=trigonal planar, 2=tetrahedral, 3=tetrahedral D) 1=tetrahedral, 2=tetrahedral, 3=trigonal planar

5 23. How many of the following molecules are polar? PCl5 COS XeO3 SeBr2 A) 2 B) 0 C) 1 D) A molecule containing a central atom with sp hybridization has geometry. A) linear B) trigonal bipyramidal C) trigonal planar D) tetrahedral 25. Identify the number of electron groups around a molecule with sp2 hybridization. A) 1 B) 2 C) 3 D) List the number of sigma bonds and pi bonds in a double bond. A) 1 sigma, 1 pi B) 2 sigma, 1 pi C) 2 sigma, 2 pi D) 1 sigma, 2 pi 27. What is the O-B-O bond angle in BO3 3-? A) less than B) C) 120 D) greater than The hybrid orbital set used by the central atom in KrF2 is. A) sp B) sp 2 C) sp 3 D) sp 3 d