ACSBR 2 Chemical Bonding - Assignment

Anglo-Chinese School (Barker Road) A Methodist Institution Founded in 1886 CHEMISTRY DEPARTMENT OF SCIENCE Name: ( ) Class: SEC 3 CHEMICAL BONDING – ASSIGNMENT ALEX LEE/2010 PAGE 1 OF 5 PURE/COMBINED/N-LEVEL 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. Metals are defined as elements which A are shiny in appearance. C can conduct electricity when solid. B are malleable and ductile. D readily give away electrons. 2. Two non-metals can form a chemical bond A by delocalizing their valence electrons. C by overlapping their valence shells. B by generating a magnetic attraction. D by transferring electrons to each other. 3. Which of the following elements does not f o r m a n i o n w h i c h h as t h e s a m e e l e c t r o n i c configuration as an argon atom? A chlorine B phosphorus C potassium D sodium 4. The element X has an electronic configuration of 2, 8, 18, 6. What ion will it form? A X2+ B X6+ C X2- D X4- 5. When magnesium forms a compound with oxygen, each magnesium atom A gives four electrons to oxygen. C shares four electrons with oxygen. B gives two electrons to oxygen. D shares two electrons with oxygen. 6. The element Y i s h i g h l y u n r e a c t i v e , a n d d o e s n o t f o r m a n y c h e m i c a l b o n d s u n d e r n o rmal circumstances. Which of the following is a possible electronic configuration of Y? A 2 B 2, 2 C 2, 6 D 2, 8, 8, 2

ALEX LEE/2010 PAGE 2 OF 5 7. A ‘triple covalent bond’ refers to the A sharing of six electrons between a metal and a non-metal. B sharing of six electrons between two non-metals. C sharing of three electrons between two metals. D sharing of three electrons between two non-metals. 8. Which of the following statements pertaining to compounds of calcium is true? A Calcium atoms have a tendency to gain two electrons during bonding. B Calcium bonds with other metallic atoms by sharing electrons. C Calcium bonds with other non-metallic atoms by transferring electrons. D Calcium can form simple molecules which have a low melting point. 9. A molecule of ammonia is shown below. How many bonded electrons are there surrounding the nitrogen atom? A 1 B 3 C 6 D 8 10. A molecule of sulfur trioxide is shown below. How many bonded electrons are there surrounding the sulfur atom? A 2 B 6 C 8 D 12 11. Which of the following best illustrates the bonding present in water? A C B D 12. Which of the following statements about ionic compounds is incorrect? A Ionic compounds are generally more soluble in water than covalent compounds. B Ionic compounds can conduct electricity at room temperature. C Ionic compounds form giant ionic lattices. D Ionic compounds have high boiling points. N H H H S O O O

ALEX LEE/2010 PAGE 3 OF 5 13. Which pair of elements below is most likely to form a compound with a low melting point? A calcium, silicon B carbon, hydrogen C fluorine, sodium D barium, zinc 14. An element Q, found in Group V of the periodic table, forms a compound with element R, found in Group VII of the periodic table. It hence can be deduced that the compound A has a formula of Q3R. C is soluble in water. B has a low boiling point. D is able to conduct electricity when liquid. 15. A diagram illustrating the bonding in a molecule of XY2, showing only the valence electrons, is shown below. What could elements X and Y be? Element X Element Y A oxygen fluorine B potassium sulfur C sulfur oxygen D sulfur sodium 16. Which substance in the table could be ethanol, CH3CH2OH? m.p. / °C b.p. / °C electrical conductivity A – 114 – 85 good when liquid B – 114 78 none when liquid C 580 718 none when liquid D 808 1465 good when liquid 17. What are the forces that hold together a crystal of table salt (solid sodium chloride) and dry ice (solid carbon dioxide)? table salt dry ice A attraction of charged ions covalent bonds B attraction of charged ions intermolecular forces C covalent bonds attraction of charged ions D covalent bonds intermolecular forces 18. The table gives information about the ability of three substances to conduct electricity. Substance Property X does not conduct under any conditions Y conducts in both molten and solid states Z conducts in both molten and aqueous states What could these three substances be? X Y Z A NaCl S Pb B Pb NaCl S C S NaCl Pb D S Pb NaCl X Y Y

ALEX LEE/2010 PAGE 4 OF 5 19. A molten sample of zinc chloride is able to conduct electricity because A it possesses a metallic element. C its ions are free to move. B it possesses mobile electrons. D its molecules are free to move. 20. The diagram below shows part of a crystal of calcium sulfide (CaS). Legend: calcium ion sulfide ion How many sulfide ions is each calcium ion attached to? A 1 B 2 C 4 D 6 Structured Questions [10 Marks] 21. Explain, in terms of structure and bonding, why (a) ionic compounds have higher boiling points than simple covalent compounds, [2] (b) ionic compounds can conduct electricity when molten, but not when solid. [2] 22. Scientists are studying a new element Ze. It does not conduct electricity, and is able to combine with other elements to make covalent and ionic compounds. It forms the ion Ze2-. Give three reasons why the element should be classified as a non-metal. [2] 1. 2. 3.

ALEX LEE/2010 PAGE 5 OF 5 23. Draw ‘dot-and-cross’ diagrams, showing only valence electrons, to illustrate the bonding in (a) magnesium chloride (MgCl2) [1] (b) nitrogen gas (N2) [1] (c) hydrogen sulfide (H2S) [1] (d) lithium phosphide (Li3P) [1] END