ACSBR 2E Chemical Bonding (Extensions) - Assignment

Anglo-Chinese School (Barker Road) A Methodist Institution Founded in 1886 CHEMISTRY DEPARTMENT OF SCIENCE Name: ( ) Class: SEC 3 CHEMICAL BONDING (EXTENSIONS) – ASSIGNMENT ALEX LEE/2010 PAGE 1 OF 5 PURE Multiple-Choice Questions [20 Marks] TOTAL SCORE / 30 Write in your selected answer for the multiple-choice questions in the boxes provided. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 1. How many chloride ions are adjacent to each sodium ion in a crystal of sodium chloride? A 1 B 2 C 4 D 6 2. An element Q reacts with chlorine to form a liquid of formula QCl2. What could be the electronic configuration of Q? A 2, 8, 1 B 2, 8, 2 C 2, 8, 6 D 2, 8, 8 3. A ‘dot and cross’ diagram showing the bonding in ammonium chloride (NH4Cl) is shown. From the above diagram, we can tell that ammonium chloride contains A covalent bonds only. C both covalent and ionic bonds. B ionic bonds only. D neither covalent nor ionic bonds. 4. In a molecule of methane (CH4), how many pairs of electrons are not involved in bonding? A 0 B 1 C 2 D 4 5. Which one of the following solids does not contain covalent bonds? A copper B diamond C methane D ice

ALEX LEE/2010 PAGE 2 OF 5 6. Which one of the following solids does not contain intermolecular forces? A graphite B iodine C sand D sulfur 7. Which of the following substances would best be used as a refractory material, i.e. able with withstand very high temperatures? A a metal C a non-metallic oxide B a metallic oxide D a plastic 8. Which of the following is not a property of pure calcium? A It has a hard, strong texture. C It is shiny in appearance. B It is able to conduct electricity. D It is solid at room temperature. 9. Which of the following elements would we expect to have the highest melting point? A argon B carbon C chlorine D mercury 10. Graphite can be used for all of the following except A as a drill bit and in heavy-duty cutting. C as a lead in pencils. B as a dry lubricant in industrial applications. D as an electrode to conduct electricity. 11. In the structure of graphite, sheets of carbon atoms are able to slide over each other easily A due to the presence of delocalized electrons between the sheets of carbon atoms. B due to the regular hexagonal arrangement of each sheet of carbon atoms. C due to the weak intermolecular forces between the sheets of carbon atoms. D due to the weak single covalent bond between the carbon atoms. 12. The structure of diamond can best be described as A a macromolecular structure with a hexagonal arrangement of carbon atoms. B a macromolecular structure with a tetrahedral arrangement of carbon atoms. C a simple molecular structure with a octahedral arrangement of carbon atoms. D a simple molecular structure with a trigonal arrangement of carbon atoms. 13. Silicon dioxide (SiO2) has a higher melting point than sodium chloride (NaCl) because the A covalent bonds within SiO2 are stronger than the covalent bonds within NaCl. B covalent bonds within SiO2 are stronger than the electrostatic forces within NaCl. C electrostatic forces within SiO2 are stronger than the intermolecular forces within NaCl. D intermolecular forces within SiO2 are stronger than the electrostatic forces within NaCl. 14. Which of the following is not a similarity between diamond and oxygen? A They are both elements. C They are both non-metals. B They both contain covalent bonds. D They both have simple molecular structures.

ALEX LEE/2010 PAGE 3 OF 5 15. Aluminium and sodium are both in Period 3 of the Periodic Table. It is observed that aluminium is a significantly better conductor of electricity c o m p a r e d t o s o d i u m . W h i c h o f t h e f o l l o w i n g statements best explains this observation? A Aluminium atoms are in a regular arrangement, whereas sodium atoms are not. B Aluminium atoms have a greater number of valence electrons compared to sodium. C Aluminium contains both positive and negative ions, unlike sodium. D Aluminium is a solid at room temperature while sodium is a liquid. 16. Bromine and chlorine are both in Group VII of the Periodic Table, and exist as diatomic molecules. However, the melting point of bromine is -7 °C, while the melting point of chlorine is significantly lower at -102 °C. Which of the following statements best explains this observation? A The covalent bonds in bromine require a larger amount of energy to overcome, compared to the electrostatic forces of attraction between chlorine molecules. B The double covalent bonds present between the bromine atoms is stronger than the single covalent bond present between the chlorine atoms. C The electrostatic forces of attraction between bromine molecules is stronger than the intermolecular forces of attraction between chlorine molecules. D The intermolecular forces of attraction between bromine molecules is stronger than the intermolecular forces of attraction between chlorine molecules. 17. The structure of silicon carbide (SiC) can be represented as follows: Which of the following is most likely to be a physical property of silicon carbide? A It has a low melting and boiling point. B It has a soft, slippery texture. C It is able to conduct electricity at room temperature. D It is insoluble in water. 18. Three new substances were discovered to have the following physical properties. Electrical Conductivity Substance Melting Point when solid when aqueous Aktize 71 °C good (insoluble) Bygnit 2512 °C poor good Ceevii 216 °C poor poor Deduce the structures of the three substances. aktize bygnit ceevii A metallic lattice giant molecular ionic lattice B metallic lattice ionic lattice simple molecular C simple molecular ionic lattice giant molecular D simple molecular metallic lattice ionic lattice

ALEX LEE/2010 PAGE 4 OF 5 19. An unknown element X was found to be liquid at room temperature, immiscible with water, and able to conduct electricity even when frozen. Which of the following could be X? A bromine B calcium C mercury D water 20. An unknown substance Y was found to be solid at room temperature, soluble in water, and unable to conduct electricity under any circumstances. Which of the following could be Y? A carbon dioxide B iodine C lithium chloride D magnesium Structured Questions [10 Marks] 21. Draw ‘dot-and-cross’ diagrams, showing only valence electrons, to illustrate the bonding in (a) aluminium oxide [1] (b) diazene (N2H2) [1] (c) nitrosyl chloride (NOCl) [1]

ALEX LEE/2010 PAGE 5 OF 5 22. (a) Describe the structure of a metal. [1] (b) Graphite is a non-metal which has a macromolecular structure. However, some of its physical properties resemble that of a metal. State two of these properties. [1] (c) Under certain circumstances, both metals and ionic compounds are able to conduct electricity. Describe how the conduction of electricity in a metal differs from that of an ionic compound. [2] 23. Silicon and carbon are both in Group IV o f t h e P e r i o d i c T a b l e. However, silicon dioxide has a melting point of 1650 °C, while carbon dioxide is gaseous at room temperature. With reference to the bonding and structure, account for this difference. [3] END