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1.
The Periodic Table above shows the positions of some elements with its proton number
given.
(a) Write the formula of th...
[1 mark]
(e) Name the type of bonding formed in the compounds in (d).
[1 mark]
(f) State two physical properties of the co...
[1 mark]
R and T
[1 mark]
Q and T
[1 mark]
(d) State whether the compounds in (c) above is an ionic or covalent compound.
...
State two pairs of elements that form covalent compounds.
[2 marks]
Write the formula of these compounds.
[2 marks]
State ...
[1 mark]
B and D
[1 mark]
B and H
[1 mark]
D and E
[1 mark]
B and G
[1 mark]
(c) Explain why the element F does not form c...
[1 mark]
(b) Particles P and Q form a compound.
Write the formula of this compound.
[2 marks]
Name the bond formed between...
(b) Particles X and Y form a compound.
Write the formula of this compound.
[2 marks]
Name the bond formed between these pa...
[1 mark]
(b) Chlorine forms two types of compound with sodium and phosphorus. Name these
compounds and explain how these c...
(b) Covalent bonding
(c) The compounds have low melting points and low boiling points.
The compounds dissolve in organic s...
(c) The element F has attained octet electron arrangement. It does not need to donate, accept or
share electrons with othe...
2 cm3
of water and benzene are poured into two separate test tubes. 2 g of solid sodium chloride are
added to each of the ...
The carbon atom combines with two oxygen atoms to form carbon dioxide molecule
which is a covalent compound.
(3)
Each carb...
After accepting an electron it forms a negatively charged chloride ion, Cl-
. (1)
Cl + e → Cl-
(1)
2.8.7 2.8.8
The Na+
and...
The intermolecular force can be easily overcome by slight heating.
Thus its melting point is low. (1)
Sodium chloride cons...
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Chapter 5 chemical bonds - p2

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Chapter 5 chemical bonds - p2

  1. 1. 1. The Periodic Table above shows the positions of some elements with its proton number given. (a) Write the formula of the compound between the elements: A and D [1 mark] B and D [1 mark] (b) Name the type of bonding formed in the compounds in (a). [1 mark] (c) State two physical properties of the compounds in (a). [2 marks] (d) Write the formula of the compound between the elements: F and D [1 mark] G and C Sekolah Tinggi Kluang Chemistry Full Set Paper 25 August 2007 5 Hour Nama Pelajar : Kelas : Markah : SECTION A Structured Items Instruction: Answer all questions in this section.
  2. 2. [1 mark] (e) Name the type of bonding formed in the compounds in (d). [1 mark] (f) State two physical properties of the compounds in (a). [2 marks] (g) D exists as diatomic covalent molecule. Draw the Lewis structure of the molecule. [2 marks] (h) Which element does not form compound with other elements? Explain your answer. [3 marks] 2. The table above show the electron arrangement of 6 elements P, Q, R, S, T and U. Write the formula of the compound formed between oxygen (O) and element P. [1 mark] State a chemical property of this oxide. [1 mark] Write the formula formed between hydrogen (H) and element T. [1 mark] State a chemical property of this compound. [1 mark] (c) Write the formula of the compound formed between the elements: S and U
  3. 3. [1 mark] R and T [1 mark] Q and T [1 mark] (d) State whether the compounds in (c) above is an ionic or covalent compound. [3 marks] (e) Which of the above elements exist as a diatomic molecule? Draw the Lewis structure of this molecule. [2 marks] (f) Write a balanced chemical equation for the reaction between the elements P and T. [2 marks] (g) Pick an element that forms amphoteric oxide. [1 mark] 3. The diagram above shows the electron arrangement of six elements U – Z.
  4. 4. State two pairs of elements that form covalent compounds. [2 marks] Write the formula of these compounds. [2 marks] State two pairs of elements that form ionic compounds. [2 marks] Write the formulae of these compounds. [2 marks] (c) State three differences in physical properties between these ionic and covalent compounds. [3 marks] (d) State one element that exists as a diatomic molecule. Draw the electron-cross structure of this molecule. [2 marks] 4. (a) Write the electron arrangement of the elements in the space provided. [4 marks] (b) Write the formulae of the compounds that formed between the elements and state whether the compounds are ionic or covalent. A and G [1 mark] B and C
  5. 5. [1 mark] B and D [1 mark] B and H [1 mark] D and E [1 mark] B and G [1 mark] (c) Explain why the element F does not form compounds with the other elements. [2 marks] 5. The figure above shows the electron arrangements of two particles P and Q. (a) Write the chemical formula of particle P [1 mark] particle Q
  6. 6. [1 mark] (b) Particles P and Q form a compound. Write the formula of this compound. [2 marks] Name the bond formed between these particles. [1 mark] Determine the relative formula mass of this compound. [3 marks] State one physical property of this compound. [1 mark] 6. The figure above shows the electron arrangement of two particles X and Y. (a) Write the chemical formula of the particle X [1 mark] particle Y [1 mark]
  7. 7. (b) Particles X and Y form a compound. Write the formula of this compound. [2 marks] Name the bond formed between these particles. [1 mark] Determine the relative formula mass of this compound. [3 marks] SECTION B Restricted Response Items Instruction: Answer all questions in this section. 7. (a) Using two examples, explain how covalent compounds are formed. 14 marks] (b) State three physical properties of covalent compounds. [3 marks] (c) Describe an experiment how you can carry out an experiment to investigate one of the properties mentioned above. [3 marks] 8. (a) Using two examples, explain how covalent compounds are formed. [14 marks] (b) State three physical properties of covalent compounds. [3 marks] Describe an experiment how you can carry out an experiment to investigate one of the properties mentioned above. [3 marks] SECTION C Instruction: Answer all questions in this section. 9. The table below shows the proton number of three elements. (a) Write the electron arrangement of the three elements.
  8. 8. [1 mark] (b) Chlorine forms two types of compound with sodium and phosphorus. Name these compounds and explain how these compounds are formed. [15 marks] (c) The compound formed between sodium and chlorine does not conduct electricity in a solid state but conducts electricity when dissolved in water. Explain. [4 marks] 10. (a) Explain the following: The melting point of naphthalene is 80o C whereas the melting point of sodium chloride is 801o C. [6 marks] When carbon electrodes are immersed into solid lead(II) bromide, the light bulb does not light up. When the lead(II) bromide is heated until it melts, the light bulb lights up. [8 marks] (b) “Oxygen can form ionic and covalent compounds”. Using examples, explain the statement. [6 marks] Answers 1) (a) (i) A2D (ii) BD2
  9. 9. (b) Covalent bonding (c) The compounds have low melting points and low boiling points. The compounds dissolve in organic solvent. (d) (i) F2D (ii) G3C2 (e) Ionic bonding (f) They have high melting points and low boiling points. The compounds dissolve in water. (g) xx xx D xo xo oo oo D (h) Element E. It has eight valence electrons. Therefore it does not need to donate, to accept or share electrons with other elements 2) (a) (i) P2O (ii) As a metallic oxide it is basic. It dissolves in water to form an alkali solution. (b) (i) HT (ii) It dissolves in water to form an acidic solution with a pH less than 7. (c) (i) U2S (ii) RT3 (iii) QT4 (d) (i) Ionic (ii) Ionic (iii) Covalent (e) T. x x xx xx T o x oo oo T o o (f) 2P + T2 → 2PT (g) R 3) (a) (i) V and U (ii) V and W (i) VU4 (ii) VW2 (b) (i) Y and X (ii) Z and W (i) YX (ii) ZW (c) (d) U 4) (a) A : 2.5 B : 2.6 C : 2.8.3 D : 2.8.4 E : 2.8.7 F : 2.8.8. G : 2.8.8.1 H : 2.8.8.2 (b) (i) G3A (ii) C2B3 (iii) DB2 (iv) HB (v)DE4 (vi) G2B (i) Ionic (ii) Ionic (iii) Covalent (iv) Ionic (v) Covalent (vi) Ionic
  10. 10. (c) The element F has attained octet electron arrangement. It does not need to donate, accept or share electrons with other elements. 5) (a) (i) P2+ (ii) Q- (b) (i) PQ2 (ii) Ionic (iii) The relative atomic mass of P = 24 and Q = 35 Thus the relative formula mass of PQ2 = 24 + 2(35) = 24 + 70 = 94 (iv) It dissolves in water. 6) (a) (i) X2- (ii) Y+ (b) (i) Y2X (ii) Ionic (iii) The relative atomic mass of X = 32 and Y = 39 Therefore the relative formula mass of Y2X = 2(39) + 32 = 78 + 32 = 110 7) (a) An ionic compound is formed when a metal reacts with a non-metal. for example a reaction between sodium metal and chlorine. (1) During the reaction, the sodium metal transfers its valence electron to the chlorine atom. (1) Na → Na+ + e (1) 2.8.1 2.8 After losing an electron sodium form an ion with a charge of +1 and (1) attain a stable octet electronic arrangement. (1) After gaining an electron, the chlorine atom forms a chloride ion with a charge of -1 and attaining a stable octet electronic arrangement. (1) Cl + e → Cl- (1) 2.8.7 2.8.8 The oppositely charged Na+ and Cl- ion attract each other to form an ionic compound with the formula NaCl. (1) Magnesium reacts with oxygen to form magnesium oxide which is an ionic compound. During the reaction, the magnesium metal transfers two valence electrons to the oxygen atom. (1) Mg → Mg2+ + 2e (1) 2.8.2 2.8 After losing two electrons, magnesium forms an ion with a charge of +2 (1) and attains a stable octet electronic arrangement. (1) After gaining two electrons, the oxygen atom forms an oxide ion with a charge of -2 and attains a stable octet electronic arrangement. (1) O + 2e → O2- (1) 2.6 2.8 The oppositely charged Mg2+ and O2- ions attract each other to form an ionic compound with the formula MgO. (1) (b) Ionic compounds in general dissolve in water but not in organic solvent; they conduct electricity in molten or aqueous solution; they have high melting and boiling points. (3)
  11. 11. 2 cm3 of water and benzene are poured into two separate test tubes. 2 g of solid sodium chloride are added to each of the test tubes. The mixture was stirred with a glass rod. (2) Result : NaCl dissolves in water but does not dissolve in benzene. (1) 8) (a) A covalent compound is formed when a non metal reacts with a non metal. (1) Each element will share its valence electrons with each other so that each atom will attain a stable duplet or octet electronic arrangement of inert gases. (1) Each pair of electron shared constitutes a covalent bond. (1) For example, in the methane molecule, one carbon atom shares its valence electrons with four hydrogen atoms to form a covalent compound with the formula CH4. Methane molecule. (3) The hydrogen atoms attain duplet electron arrangement. (1) The carbon atom attain the octet electron arrangement. (1) Carbon dioxide molecule
  12. 12. The carbon atom combines with two oxygen atoms to form carbon dioxide molecule which is a covalent compound. (3) Each carbon and oxygen atoms attain octet electronic arrangement. (2) (b) Covalent compounds in general dissolve in organic but not in polar solvent like water. They do not conduct electricity in any state; they have low melting and boiling points. (3) 2 cm3 of water and benzene are poured into two separate test tubes. 2 g of solid naphthalene are added to each of the test tubes. The mixture is stirred with a glass rod. (2) Result : Naphthalene dissolves in benzene but does not dissolve in water. (1) 9) (a) Na : 2.8.1 P : 2.8.5 Cl : 2.8.7 (1) (b) Chlorine reacts with sodium to form an ionic compound. (1) The sodium atom has one valence electron. (1) It donates the valence electron to the chlorine atom so as to attain electron arrangement of inert gas. (1) Na → Na+ + e (1) 2.8.1 2.8 After losing the electron, it forms a univalent positive ion, Na+ . (1) The chlorine atom has seven valence electrons. To attain octet electron configuration, it accepts the valence electron transferred from the sodium atom. (1)
  13. 13. After accepting an electron it forms a negatively charged chloride ion, Cl- . (1) Cl + e → Cl- (1) 2.8.7 2.8.8 The Na+ and Cl- ions attract each other to form an ionic compound. (1) Chlorine reacts with phosphorus to form a covalent compound phosphorus trichloride, PCl3. (1) The phosphorus atom has 5 valence electrons and need another three electrons to attain octet electron configuration. (1) The chlorine atom has 7 valence electrons and need another one electron to attain octet electron configuration. (1) Thus one phosphorus atom will share three of its valence electrons with three chlorine atoms. (3) (c) The sodium ions and the chloride ions are attracted by strong electrostatic force. (1) In the solid state, the ions are not free to move to carry charges and thus do not conduct electricity. (1) When melted, the ions are free to move to carry charges and thus conduct electricity in molten state. (1) NaCl(s) →heat Na+ (l) + Cl- (l) (1) 10) (a) (i) The naphthalene is a covalent compound. (1) The molecules are attracted by weak intermolecular forces. (1)
  14. 14. The intermolecular force can be easily overcome by slight heating. Thus its melting point is low. (1) Sodium chloride consists of oppositely charged Na+ and Cl- ions. (1) These ions are attracted by strong electrostatic force. (1) It needs strong heating to overcome the strong electrostatic force. Thus its melting point is high. (1) (ii) The Pb2+ ions and the Br- ions are attracted by a strong electrostatic force. (1) In the solid state, the ions are not free to move to carry charges and thus do not conduct electricity. (1) When melted, the ions are free to move. The Pb2+ ions move to the cathode whereas the Br- move to the anode. (1) The Br- ions discharged at the anode by releasing electrons. (1) 2Br- → Br2 + 2e (1) The electrons then move from the anode to the cathode through the wire and the bulb filament, thus lighting up the bulb. (1) The Pb2+ ions discharge at the cathode by accepting the electrons. (1) Pb2+ + 2e → Pb (1) (b) The electron configuration of oxygen atom is 2.6 (1) It needs two electrons to attain a stable octet electronic configuration. (1) If oxygen reacts with metals it will form ionic compounds. (1) The metallic atom will transfer its valence electrons to the oxygen atom, resulting in the formation of positively charged metallic ions and negatively charged oxide ions which then attract each other to form the ionic bond. (2) If oxygen reacts with non-metallic element it attains the octet electronic configuration by sharing its valence electron with the non-metallic element. (1)

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