Unit 1 Atomic Structure, Bonding and Periodicity

Transcription

1 Surname Other Names Leave blank Centre Number Candidate Number Candidate Signature General Certificate of Education January 2001 Advanced Subsidiary Examination CHEMISTRY CHM1 Unit 1 Atomic Structure, Bonding and Periodicity Friday 12 January 2001 Morning Session In addition to this paper you will require: a Periodic Table; a calculator. Time allowed: 1 hour 30 minutes Instructions Use blue or black ink or ball-point pen. Fill in the boxes at the top of this page. Answer all questions in Section A and Section B in the spaces provided. All working must be shown. Do all rough work in this book. Cross through any work you do not want marked. Number For ExaminerÕs Use Mark Number Mark Information The maximum mark for this paper is 90. Mark allocations are shown in brackets. This paper carries 30 per cent of the total marks for AS. For Advanced Level this paper carries 15 per cent of the total marks. You are expected to use a calculator where appropriate. The following data may be required. Gas constant R = 8.31 J mol 1 K 1 Your answers to questions in Section B should be written in continuous prose, where appropriate. You will be assessed on your ability to use an appropriate form and style of writing, to organise relevant information clearly and coherently, and to use specialist vocabulary, where appropriate. Total (Column 1) Total (Column 2) TOTAL Advice You are advised to spend about 1 hour on Section A and about 30 minutes on Section B. ExaminerÕs Initials APW/0101/CHM1

2 2 SECTION A Answer all questions in the spaces provided. 1 (a) Give the relative mass and relative charge of a neutron. Relative mass... Relative charge... (2 marks) (b) In terms of the number of their fundamental particles, what do two isotopes of an element have in common and how do they differ? In common... Difference... (2 marks) (c) Give the complete atomic symbol, including mass number and atomic number, for an atom of the isotope with 22 neutrons and 19 electrons.... (2 marks) (d) In a mass spectrometer the isotopes of an element are separated and two measurements are made for each isotope. (i) Which two measurements are made for each isotope? Measurement 1... Measurement 2... (ii) State how the detector in a mass spectrometer works. (iii) Why is a mass spectrometer incapable of distinguishing between the ions 14 N + and 14 N 2 2 +? (5 marks) APW/0101/CHM1

3 3 (e) Using arrows and to represent electrons, complete the energy-level diagram below to show the electronic arrangement in an atom of carbon. 2p 2s 1s (2 marks) (f) In terms of sub-levels, give the electronic configuration of the carbon ion C (1 mark) 14 TURN OVER FOR THE NEXT QUESTION Turn over APW/0101/CHM1

4 4 2 (a) The mass of one atom of 12 C is g. Use this information to calculate a value for the Avogadro constant. Show your working (2 marks) (b) Give the meaning of the term empirical formula (1 mark) (c) Define the term relative molecular mass (2 marks) (d) The empirical formula of a compound is CHO and its relative molecular mass has the value 174. Determine the molecular formula of this compound and show your working (2 marks) (e) A compound with molecular formula CH 4 O burns in air to form carbon dioxide and water. Write a balanced equation for this reaction.... (1 mark) 8 APW/0101/CHM1

5 5 3 Ammonium nitrate can be prepared by the reaction between ammonia and nitric acid: NH 3 + HNO 3 NH 4 NO 3 (a) The concentration of a nitric acid solution is 2.00 mol dm 3. Calculate the volume of this solution which would be required to react with exactly 20.0 g of ammonia (4 marks) (b) A sample of ammonium nitrate decomposed on heating as shown in the equation below. NH 4 NO 3 2H 2 O + N O 2 On cooling the resulting gases to 298 K, the volume of nitrogen and oxygen together was found to be m 3 at a pressure of 95.0 kpa. (i) State the ideal gas equation and use it to calculate the total number of moles of nitrogen and oxygen formed. (The gas constant R = 8.31 J mol 1 K 1 ) (ii) Using your answer to part (b)(i), deduce the number of moles of ammonium nitrate decomposed and hence calculate the mass of ammonium nitrate in the sample. Moles of ammonium nitrate... Mass of ammonium nitrate... (6 marks) 10 Turn over APW/0101/CHM1

6 6 4 The diagram below shows the trend in the first ionisation energies of the elements from neon to aluminium. First ionisation energy Ne Na Mg Al Si P S Element (a) Draw crosses on the graph to show the first ionisation energies of silicon, phosphorus and sulphur. (3 marks) (b) Write an equation to illustrate the process which occurs during the first ionisation of neon.... (1 mark) (c) Explain why the first ionisation energy of neon and that of magnesium are both higher than that of sodium. Explanation for neon Explanation for magnesium (4 marks) APW/0101/CHM1

7 7 (d) Explain why the first ionisation energy of aluminium is lower than that of magnesium (2 marks) (e) State which one of the elements neon, sodium, magnesium, aluminium and silicon has the lowest melting point and explain your answer in terms of the structure and bonding present in that element. Element with lowest melting point... Explanation (3 marks) (f) State which one of the elements neon, sodium, magnesium, aluminium and silicon has the highest melting point and explain your answer in terms of the structure and bonding present in that element. Element with highest melting point... Explanation (3 marks) 16 TURN OVER FOR THE NEXT QUESTION Turn over APW/0101/CHM1

8 8 5 (a) Define the term electronegativity (2 marks) (b) State and explain the trend in electronegativity down Group II. Trend... Explanation (3 marks) (c) Write an equation for the reaction of strontium with water, and suggest an approximate value for the ph of the resulting solution. Equation... ph... (2 marks) (d) Describe what is seen when an aqueous solution of barium chloride is added to dilute sulphuric acid. Write an equation for the reaction which occurs. Observation... Equation... (2 marks) (e) Give two examples which illustrate the atypical properties of beryllium compounds in Group II. Example 1... Example 2... (2 marks) (f) Give one feature of the beryllium ion which causes the atypical properties of beryllium compounds.... (1 mark) 12 APW/0101/CHM1

9 9 SECTION B Answer the question below in the space provided on pages 9 to 12 of this booklet. 6 (a) With the aid of diagrams, describe the structure of, and bonding in, crystals of sodium chloride, graphite and magnesium. In each case, explain how the melting point and the ability to conduct electricity of these substances can be understood by a consideration of the structure and bonding involved. (23 marks) (b) Explain how the electron-pair repulsion theory can be used to predict the shapes of the molecules H 2 O and PF 5. Illustrate your answer with diagrams of the molecules on which the bond angles are shown. (7 marks) END OF QUESTIONS Turn over APW/0101/CHM1

10 10 APW/0101/CHM1

11 11 Turn over APW/0101/CHM1

12 12 APW/0101/CHM1

13 Surname Other Names Leave blank Centre Number Candidate Number Candidate Signature General Certificate of Education June 2001 Advanced Subsidiary Examination CHEMISTRY CHM1 Unit 1 Atomic Structure, Bonding and Periodicity Monday 4 June 2001 Afternoon Session In addition to this paper you will require: a Periodic Table; a calculator. Time allowed: 1 hour 30 minutes Instructions Use blue or black ink or ball-point pen. Fill in the boxes at the top of this page. Answer all questions in Section A and Section B in the spaces provided. All working must be shown. Do all rough work in this book. Cross through any work you do not want marked. Number For ExaminerÕs Use Mark Number Mark Information The maximum mark for this paper is 90. Mark allocations are shown in brackets. This paper carries 30 per cent of the total marks for AS. For Advanced Level this paper carries 15 per cent of the total marks. You are expected to use a calculator where appropriate. The following data may be required. Gas constant R = 8.31 J mol 1 K 1 Your answers to questions in Section B should be written in continuous prose, where appropriate. You will be assessed on your ability to use an appropriate form and style of writing, to organise relevant information clearly and coherently, and to use specialist vocabulary, where appropriate. Total (Column 1) Total (Column 2) TOTAL Advice You are advised to spend about 1 hour on Section A and about 30 minutes on Section B. ExaminerÕs Initials APW/0201/CHM1

14 2 SECTION A Answer all questions in the spaces provided. 1 (a) Define the terms mass number and atomic number of an atom. Mass number... Atomic number... (2 marks) (b) Give the symbol, including the mass number and the atomic number, for the atom which has 3 fewer neutrons and 2 fewer protons than 14 7 N.... (2 marks) (c) In terms of sub-levels, give the complete electronic configuration of the nitrogen atom, N, and of the nitride ion, N 3. N... N 3... (2 marks) (d) Define the term relative atomic mass of an element (2 marks) APW/0201/CHM1

15 3 (e) When a pure, gaseous sample of element X is introduced into a mass spectrometer, four mononuclear, singly-charged ions are detected, as shown in the spectrum below. Relative abundance m/z (i) Describe the process by which the gaseous sample of X is converted into ions in a mass spectrometer. (ii) What adjustment is made to the operating conditions in order to direct the different ions, in turn, onto the detector of a mass spectrometer? (iii) Use data from the spectrum above to calculate the relative atomic mass of X. (iv) Identify the element X. (7 marks) 15 Turn over APW/0201/CHM1

16 4 2 (a) What is the name given to the number of molecules in one mole of carbon dioxide?... (1 mark) (b) (i) State the ideal gas equation. (ii) Calculate the volume of 1.00 mol of carbon dioxide gas at 298K and 100 kpa. (The gas constant R = 8.31 J mol 1 K 1 ) (iii) Calculate the mass of carbon dioxide gas at 273 K and 500 kpa contained in a cylinder of volume m 3. (7 marks) APW/0201/CHM1

17 5 (c) Hydrogen can be made by the reaction of hydrochloric acid with magnesium according to the equation 2HCl + Mg MgCl 2 + H 2 What mass of hydrogen is formed when 100 cm 3 of hydrochloric acid of concentration 5.0moldm 3 reacts with an excess of magnesium? (3 marks) (d) A compound of iron contains 38.9% by mass of iron and 16.7% by mass of carbon, the remainder being oxygen. (i) Determine the empirical formula of the iron compound. (ii) When one mole of this iron compound is heated, it decomposes to give one mole of iron(ii) oxide, FeO, one mole of carbon dioxide and one mole of another gas. Identify this other gas. (The molecular formula of the iron compound is the same as its empirical formula.) (4 marks) 15 Turn over APW/0201/CHM1

18 6 3 (a) Name the type of force that holds the particles together in an ionic crystal.... (1 mark) (b) What is a covalent bond?... (1 mark) (c) State how a co-ordinate bond is formed (2 marks) (d) Describe the bonding in a metal (2 marks) (e) A molecule of hydrogen chloride has a dipole and molecules of hydrogen chloride attract each other by permanent dipole dipole forces. Molecules of chlorine are non-polar. (i) What is a permanent dipole? (ii) Explain why a molecule of hydrogen chloride is polar. (iii) Name the type of force which exists between molecules of chlorine. (5 marks) APW/0201/CHM1

19 7 (f) Show, by means of a diagram, how two molecules of hydrogen fluoride are attracted to each other by hydrogen bonding; include all lone-pair electrons and partial charges in your diagram. (3 marks) (g) Why is there no hydrogen bonding between molecules of hydrogen bromide? (1 mark) 15 TURN OVER FOR THE NEXT QUESTION Turn over APW/0201/CHM1

20 8 4 (a) Describe the motion of the particles in solid iodine and in iodine vapour. Motion in solid iodine Motion in iodine vapour (3 marks) (b) Explain why solid iodine vaporises when warmed gently (2 marks) (c) Silver and sodium chloride melt at similar temperatures. Give two physical properties of silver which are different from those of sodium chloride and, in each case, give one reason why the property of silver is different from that of sodium chloride. First property of silver... Reason for difference Second property of silver... Reason for difference (4 marks) APW/0201/CHM1

21 9 (d) Draw the shapes of BeCl 2, NCl 3 and BeCl 2 4. In each case, show any lone-pair electrons on the central atom and state the value of the bond angle. BeCl 2 NCl 3 BeCl 2 4 (6 marks) 15 TURN OVER FOR SECTION B Turn over APW/0201/CHM1

22 10 SECTION B Answer the question below in the space provided on pages 10 to 16 of this booklet. 5 (a) In terms of structure and bonding, describe and explain fully the difference between the melting points of the Period 3 elements aluminium, silicon and phosphorus. (12 marks) (b) Describe and explain the difference between the electrical conductivities of the elements aluminium, silicon and phosphorus. (4 marks) (c) State appropriate conditions under which magnesium and calcium react with water. Give equations for the reactions and describe what you would observe. (7 marks) (d) Beryllium is an atypical element in Group II. Justify this statement by comparing the reactions of beryllium hydroxide and magnesium hydroxide with hydrochloric acid and also with sodium hydroxide. Write equations to illustrate your answer. (7 marks) END OF QUESTIONS APW/0201/CHM1

23 11 Turn over APW/0201/CHM1

24 12 APW/0201/CHM1

25 13 Turn over APW/0201/CHM1

26 14 APW/0201/CHM1

27 15 Turn over APW/0201/CHM1

28 16 APW/0201/CHM1

29 Surname Other Names Leave blank Centre Number Candidate Number Candidate Signature General Certificate of Education January 2002 Advanced Subsidiary Examination CHEMISTRY CHM1 Unit 1 Atomic Structure, Bonding and Periodicity Friday 11 January 2002 Afternoon Session In addition to this paper you will require: a Periodic Table; a calculator. Time allowed: 1 hour 30 minutes Instructions Use blue or black ink or ball-point pen. Fill in the boxes at the top of this page. Answer all questions in Section A and Section B in the spaces provided. All working must be shown. Do all rough work in this book. Cross through any work you do not want marked. Number For Examiner s Use Mark Number Mark Information The maximum mark for this paper is 90. Mark allocations are shown in brackets. This paper carries 30 per cent of the total marks for AS. For Advanced Level this paper carries 15 per cent of the total marks. You are expected to use a calculator where appropriate. The following data may be required. Gas constant R = 8.31 J mol 1 K 1 Your answers to questions in Section B should be written in continuous prose, where appropriate. You will be assessed on your ability to use an appropriate form and style of writing, to organise relevant information clearly and coherently, and to use specialist vocabulary, where appropriate. Total (Column 1) Total (Column 2) TOTAL Advice You are advised to spend about 1 hour on Section A and about 30 minutes on Section B. Examiner s Initials APW/0102/CHM1

30 2 SECTION A Answer all questions in the spaces provided. 1 (a) Define the term atomic number of an element.... (1 mark) (b) Give the symbol, including mass number and atomic number, for an atom of an element which contains 12 neutrons and 11 electrons.... (2 marks) (c) In terms of s and p sub-levels, give the electronic configuration of an aluminium atom.... (1 mark) (d) How many neutrons are there in one 27 Al atom?... (1 mark) (e) Define the term relative atomic mass of an element (2 marks) (f) Parts (i) to (iv) below refer to the operation of a mass spectrometer. (i) Name the device used to ionise atoms in a mass spectrometer. (ii) Why is it necessary to ionise atoms before acceleration? APW/0102/CHM1

31 3 (iii) What deflects the ions? (iv) What is adjusted in order to direct ions of different mass to charge ratio onto the detector? (4 marks) (g) A meteorite was found to contain three isotopes of element X. A mass spectrometer gave the following information about these isotopes. m/z Relative abundance (i) Calculate the relative atomic mass of X. (ii) Using the Periodic Table, suggest the most likely identity of element X. (iii) Suggest one reason why the relative atomic mass of X, given in the Periodic Table, differs from your answer to part (g)(i). (5 marks) 16 Turn over APW/0102/CHM1

32 4 2 (a) The diagram below represents a part of the structure of sodium chloride. The ionic charge is shown on the centre of only one of the ions. (i) (ii) On the diagram, mark the charges on the four negative ions. What change occurs to the motion of the ions in sodium chloride when it is heated from room temperature to a temperature below its melting point? (2 marks) (b) Sodium chloride can be formed by reacting sodium with chlorine. (i) Write an equation for this reaction. (ii) A chloride ion has one more electron than a chlorine atom. In the formation of sodium chloride, from where does this electron come? (2 marks) (c) In some ionic compounds the chloride ions are polarised. (i) What is a polarised chloride ion? (ii) What feature of a cation causes a chloride ion to become polarised? (2 marks) APW/0102/CHM1

33 5 (d) (i) What is a covalent bond? (ii) What property of the atoms joined by a covalent bond causes the bond to be polar? (3 marks) 9 TURN OVER FOR THE NEXT QUESTION Turn over APW/0102/CHM1

34 6 3 (a) The shape of the molecule BCl 3 and that of the unstable molecule CCl 2 are shown below. Cl Cl B Cl Cl C Cl (i) Why is each bond angle exactly 120 in BCl 3? (ii) Predict the bond angle in CCl 2 and explain why this angle is different from that in BCl 3 Predicted bond angle... Explanation... (5 marks) (b) Give the name which describes the shape of molecules having bond angles of '. Give an example of one such molecule. Name of shape... Example... (2 marks) (c) The shape of the XeF 4 molecule is shown below. F F Xe F F (i) State the bond angle in XeF 4 (ii) Suggest why the lone pairs of electrons are opposite each other in this molecule. APW/0102/CHM1

35 7 (iii) Name the shape of this molecule, given that the shape describes the positions of the Xe and F atoms only. (4 marks) (d) Draw a sketch of the NF 3 molecule. Indicate in your sketch any lone pairs of electrons on nitrogen. (2 marks) 13 TURN OVER FOR THE NEXT QUESTION Turn over APW/0102/CHM1

36 8 4 (a) State the meaning of the term electronegativity (2 marks) (b) State and explain the trend in electronegativity values across Period 3 from sodium to chlorine. Trend... Explanation (3 marks) (c) What is meant by the term first ionisation energy? (2 marks) (d) The diagram below shows the variation in first ionisation energy across Period 3. First ionisation energy Na Mg Al Si P S Cl Ar Period 3 element (i) What is the maximum number of electrons that can be accommodated in an s sub-level? APW/0102/CHM1

37 9 (ii) What evidence from the diagram supports your answer to part (d)(i)? (iii) What evidence from the diagram supports the fact that the 3p sub-level is higher in energy than the 3s? (iv) What evidence from the diagram supports the fact that no more than three unpaired electrons can be accommodated in the 3p sub-level? (5 marks) 12 TURN OVER FOR THE NEXT QUESTION Turn over APW/0102/CHM1

38 10 5 (a) (i) Describe the bonding in a metal. (ii) Explain why magnesium has a higher melting point than sodium. (4 marks) (b) Why do diamond and graphite both have high melting points? (3 marks) (c) Why is graphite a good conductor of electricity?... (1 mark) (d) Why is graphite soft? (2 marks) 10 APW/0102/CHM1

39 11 SECTION B Answer both questions in the spaces provided on pages 12 to 16 of this booklet. 6 (a) A small sample of barium metal was added to water in a flask. When the reaction had ceased, the contents of the flask were treated with a small amount of dilute aqueous sodium sulphate. Describe all that you would observe and write equations, with state symbols, for the reactions that occur. (8 marks) (b) Dilute sodium hydroxide solution was added dropwise until in excess to separate dilute aqueous solutions of beryllium chloride, magnesium chloride and barium chloride. Describe what you would observe in each case and account for your observations. (8 marks) (c) (i) A naturally occurring compound of calcium contains by mass 23.29% of calcium, 18.64% of sulphur and 2.32% of hydrogen, the remainder being oxygen. Determine the empirical formula of this compound. (ii) For any compound, what is the relationship between empirical and molecular formula? What additional information is required to determine a molecular formula from an empirical formula? (5 marks) 7 The chloride of an element Z reacts with water according to the following equation. ZCl 4 (l) + 2H 2 O(l) ZO 2 (s) + 4HCl(aq) A g sample of ZCl 4 was added to water. The solid ZO 2 was removed by filtration and the resulting solution was made up to 250 cm 3 in a volumetric flask. A 25.0 cm 3 portion of this solution was titrated against a mol dm 3 solution of sodium hydroxide, of which 21.7 cm 3 were required to reach the end point. Use this information to calculate the number of moles of HCl produced and hence the number of moles of ZCl 4 present in the sample. Calculate the relative molecular mass, M r, of ZCl 4. From your answer deduce the relative atomic mass, A r, of element Z and hence its identity. (9 marks) END OF QUESTIONS Turn over APW/0102/CHM1

40 12 APW/0102/CHM1

41 13 Turn over APW/0102/CHM1

42 14 APW/0102/CHM1

43 15 Turn over APW/0102/CHM1

44 16 APW/0102/CHM1

45 Surname Other Names Leave blank Centre Number Candidate Number Candidate Signature General Certificate of Education June 2002 Advanced Subsidiary Examination CHEMISTRY CHM1 Unit 1 Atomic Structure, Bonding and Periodicity Wednesday 29 May 2002 Morning Session In addition to this paper you will require: the AQA Periodic Table (Reference CHEM/PT/EX); a calculator. Time allowed: 1 hour 30 minutes Instructions Use blue or black ink or ball-point pen. Fill in the boxes at the top of this page. Answer all questions in Section A and Section B in the spaces provided. All working must be shown. Do all rough work in this book. Cross through any work you do not want marked. Number For Examiner s Use Mark Number Mark Information The maximum mark for this paper is 90. Mark allocations are shown in brackets. This paper carries 30 per cent of the total marks for AS. For Advanced Level this paper carries 15 per cent of the total marks. You are expected to use a calculator where appropriate. The following data may be required. Gas constant R = 8.31 J mol 1 K 1 Your answers to questions in Section B should be written in continuous prose, where appropriate. You will be assessed on your ability to use an appropriate form and style of writing, to organise relevant information clearly and coherently, and to use specialist vocabulary, where appropriate. Total (Column 1) Total (Column 2) TOTAL Advice You are advised to spend about 1 hour on Section A and about 30 minutes on Section B. Examiner s Initials APW/0202/CHM1

46 2 SECTION A Answer all questions in the spaces provided. 1 (a) The mass of one mole of 1 H atoms is g and that of one 1 H atom is g. Use these data to calculate a value for the Avogadro constant accurate to five significant figures. Show your working (2 marks) (b) How does the number of atoms in one mole of argon compare with the number of molecules in one mole of ammonia?... (1 mark) (c) A sample of ammonia gas occupied a volume of m 3 at 298 K and 98.0 kpa. Calculate the number of moles of ammonia in the sample. (The gas constant R = 8.31JK 1 mol 1 ) (3 marks) APW/0202/CHM1

47 3 (d) A solution containing mol of ammonia was made up to 250 cm 3 in a volumetric flask by adding water. Calculate the concentration of ammonia in this final solution and state the appropriate units (2 marks) (e) A different solution of ammonia was reacted with sulphuric acid as shown in the equation below. 2NH 3 (aq) + H 2 SO 4 (aq) (NH 4 ) 2 SO 4 (aq) In a titration, 25.0 cm 3 of a 1.24 mol dm 3 solution of sulphuric acid required 30.8 cm 3 of this ammonia solution for complete reaction. (i) Calculate the concentration of ammonia in this solution. (ii) Calculate the mass of ammonium sulphate in the solution at the end of this titration. (6 marks) (f) The reaction of magnesium nitride, Mg 3 N 2, with water produces ammonia and magnesium hydroxide. Write an equation for this reaction.... (2 marks) 16 Turn over APW/0202/CHM1

48 4 2 (a) An ammonium ion, made by the reaction between an ammonia molecule and a hydrogen ion, can be represented as shown in the diagram below. H H N H H + (i) Name the type of bond represented in the diagram by N H (ii) Name the type of bond represented in the diagram by N H (iii) In terms of electrons, explain why an arrow is used to represent this N H bond. (iv) In terms of electron pairs, explain why the bond angles in the NH 4 + ion are all (7 marks) (b) Define the term electronegativity (2 marks) APW/0202/CHM1

49 5 (c) δ δ+ A bond between nitrogen and hydrogen can be represented as N H (i) In this representation, what is the meaning of the symbol δ+? (ii) From this bond representation, what can be deduced about the electronegativity of hydrogen relative to that of nitrogen? (2 marks) 11 TURN OVER FOR THE NEXT QUESTION Turn over APW/0202/CHM1

50 6 3 The table below shows some values of melting points and some heat energies needed for melting. Substance I 2 NaCl HF HCl HI Melting point/k Heat energy for melting /kjmol (a) Name three types of intermolecular force. Force 1... Force 2... Force 3... (3 marks) (b) (i) Describe the bonding in a crystal of iodine. (ii) Name the crystal type which describes an iodine crystal. (iii) Explain why heat energy is required to melt an iodine crystal. (4 marks) APW/0202/CHM1

51 7 (c) In terms of the intermolecular forces involved, suggest why (i) hydrogen fluoride requires more heat energy for melting than does hydrogen chloride, (ii) hydrogen iodide requires more heat energy for melting than does hydrogen chloride. (5 marks) (d) (i) Explain why the heat energy required to melt sodium chloride is large. (ii) The heat energy needed to vaporise one mole of sodium chloride (171kJmol 1 ) is much greater than the heat energy required to melt one mole of sodium chloride. Explain why this is so. (3 marks) (e) In terms of its structure and bonding, suggest why graphite has a very high melting point (2 marks) 17 Turn over APW/0202/CHM1

52 8 4 (a) State the trend in atomic radius down Group II from Be to Ba and give a reason for this trend. Trend... Reason (2 marks) (b) State and explain the trend in melting points of the elements down Group II from Be to Ba. Trend... Explanation (3 marks) (c) State the trend in reactivity with water of the elements down Group II from Be to Ba. Write an equation for the reaction of magnesium with steam and an equation for the reaction of strontium with water. Trend... Equation for magnesium... Equation for strontium... (3 marks) (d) Sulphates of the Group II elements from Be to Ba have different solubilities. Give the formula of the least soluble of these sulphates and state one use that depends upon the insolubility of this sulphate. Formula... Use... (2 marks) APW/0202/CHM1

53 9 (e) A solution contains ions of a Group II element, M. When aqueous sodium hydroxide is added a white precipitate forms. This precipitate dissolves in an excess of aqueous sodium hydroxide. Identify M and write ionic equations for the two reactions. Identity of M... Equation 1... Equation 2... (3 marks) (f) With the exception of beryllium chloride, Group II chlorides are classed as ionic. Explain why beryllium chloride is different by considering how a beryllium ion would interact with a chloride ion (3 marks) 16 TURN OVER FOR SECTION B Turn over APW/0202/CHM1

54 10 SECTION B Answer both the questions below in the space provided on pages 10 to 16 of this booklet. 5 (a) State the relative charge and relative mass of a proton, of a neutron and of an electron. In terms of particles, explain the relationship between two isotopes of the same element. Explain why these isotopes have identical chemical properties. (7 marks) (b) Define the term relative atomic mass. An element exists as a mixture of three isotopes. Explain, in detail, how the relative atomic mass of this element can be calculated from data obtained from the mass spectrum of the element. (7 marks) 6 (a) Explain why certain elements in the Periodic Table are classified as p-block elements. Illustrate your answer with an example of a p-block element and give its electronic configuration. (3 marks) (b) Explain the meaning of the term periodicity as applied to the properties of rows of elements in the Periodic Table. Describe and explain the trends in atomic radius, in electronegativity and in conductivity for the elements sodium to argon. (13 marks) END OF QUESTIONS APW/0202/CHM1

55 11 Turn over APW/0202/CHM1

56 12 APW/0202/CHM1

57 13 Turn over APW/0202/CHM1

58 14 APW/0202/CHM1

59 15 Turn over APW/0202/CHM1

60 16 APW/0202/CHM1

61 Surname Other Names Leave blank Centre Number Candidate Number Candidate Signature General Certificate of Education January 2003 Advanced Subsidiary Examination CHEMISTRY CHM1 Unit 1 Atomic Structure, Bonding and Periodicity Friday 10 January 2003 Morning Session In addition to this paper you will require: a calculator. Number For Examiner s Use Mark Number Mark Time allowed: 1 hour 30 minutes 1 2 Instructions Use blue or black ink or ball-point pen. Fill in the boxes at the top of this page. Answer all questions in Section A and Section B in the spaces provided. All working must be shown. Do all rough work in this book. Cross through any work you do not want marked. The Periodic Table/Data Sheet is provided on pages 3 and 4. Detach this perforated sheet at the start of the examination Information The maximum mark for this paper is 90. Mark allocations are shown in brackets. This paper carries 30 per cent of the total marks for AS. For Advanced Level this paper carries 15 per cent of the total marks. You are expected to use a calculator where appropriate. The following data may be required. Gas constant R = 8.31 J K 1 mol 1 Your answers to questions in Section B should be written in continuous prose, where appropriate. You will be assessed on your ability to use an appropriate form and style of writing, to organise relevant information clearly and coherently, and to use specialist vocabulary, where appropriate. Total (Column 1) Total (Column 2) TOTAL Examiner s Initials Advice You are advised to spend about 1 hour on Section A and about 30 minutes on Section B. APW/0103/CHM1

62 2 SECTION A Answer all questions in the spaces provided. 1 (a) Complete the following table. Particle Relative charge Relative mass Proton Neutron Electron (3 marks) (b) An atom of element Z has two more protons and two more neutrons than an atom of S. Give the symbol, including mass number and atomic number, for this atom of Z (2 marks) (c) Complete the electronic configurations for the sulphur atom, S, and the sulphide ion, S 2. S ls 2... S 2 ls 2... (2 marks) (d) State the block in the Periodic Table in which sulphur is placed and explain your answer. Block Explanation... (2 marks) APW/0103/CHM1

63 3 The Periodic Table of the Elements The atomic numbers and approximate relative atomic masses shown in the table are for use in the examination unless stated otherwise in an individual question. APW/0103/CHM1 I II III IV V VI VII He Helium Key 1.0 H Hydrogen Ne Neon F Fluorine O Oxygen N Nitrogen C Carbon B Boron relative atomic mass Li Lithium Li Lithium 3 atomic number 9.0 Be Beryllium Ar Argon Cl Chlorine S Sulphur P Phosphorus Si Silicon Al Aluminium Mg Magnesium Kr Krypton Br Bromine Se Selenium As Arsenic Ge Germanium Ga Gallium Zn Zinc Cu Copper Ni Nickel Co Cobalt Fe Iron Mn Manganese Cr Chromium V Vanadium Ti Titanium Sc Scandium Ca Calcium Na Sodium K Potassium Xe Xenon I Iodine Te Tellurium Sb Antimony Sn Tin In Indium Cd Cadmium Ag Silver Pd Palladium Rh Rhodium Ru Ruthenium Tc Technetium Mo Molybdenum Nb Niobium Zr Zirconium Y Yttrium Sr Strontium Rn Radon At Astatine Po Polonium Bi Bismuth Pb Lead Tl Thallium Hg Mercury Au Gold Pt Platinum Ir Iridium Os Osmium Re Rhenium W Tungsten Ta Tantalum Hf Hafnium La Lanthanum 57 * Ba Barium Ac Actinium Ra Radium Rb Rubidium Cs Caesium Fr Francium Lu Lutetium Yb Ytterbium Tm Thulium Er Erbium Ho Holmium Dy Dysprosium Tb Terbium Gd Gadolinium Eu Europium Sm Samarium Pm Promethium Nd Neodymium Pr Praseodymium Ce Cerium Th Thorium 90 * Lanthanides (260) Lr Lawrencium 103 (259) No Nobelium 102 (258) Md Mendelevium 101 (257) Fm Fermium 100 (252) Es Einsteinium Cf Californium Bk Berkelium Cm Curium Am Americium Pu Plutonium Np Neptunium U Uranium Pa Protactinium Actinides

64 4 Table 1 Proton n.m.r chemical shift data Type of proton δ/ppm RCH R 2 CH R 3 CH RCOCH ROCH RCOOCH ROH Table 2 Infra-red absorption data Bond Wavenumber/cm 1 C H C C C C C O C O O H (alcohols) O H (acids) APW/0103/CHM1

65 5 (e) Sodium sulphide, Na 2 S, is a high melting point solid which conducts electricity when molten. Carbon disulphide, CS 2, is a liquid which does not conduct electricity. (i) Deduce the type of bonding present in Na 2 S and that present in CS 2 Bonding in Na 2 S... Bonding in CS 2... (ii) By reference to all the atoms involved explain, in terms of electrons, how Na 2 S is formed from its atoms. (iii) Draw a diagram, including all the outer electrons, to represent the bonding present in CS 2 (iv) When heated with steam, CS 2 reacts to form hydrogen sulphide, H 2 S, and carbon dioxide. Write an equation for this reaction. (7 marks) 16 TURN OVER FOR THE NEXT QUESTION Turn over APW/0103/CHM1

66 6 2 (a) Calculate the concentration, in mol dm 3, of the solution formed when 19.6 g of hydrogen chloride, HCl, are dissolved in water and the volume made up to 250 cm (3 marks) (b) The carbonate of metal M has the formula M 2 CO 3. The equation for the reaction of this carbonate with hydrochloric acid is given below. M 2 CO 3 + 2HCl 2MCl + CO 2 +H 2 O A sample of M 2 CO 3, of mass g, required the addition of 21.7 cm mol dm 3 solution of hydrochloric acid for complete reaction. of a (i) Calculate the number of moles of hydrochloric acid used. (ii) Calculate the number of moles of M 2 CO 3 in g. (iii) Calculate the relative molecular mass of M 2 CO 3 (iv) Deduce the relative atomic mass of M and hence suggest its identity. Relative atomic mass of M... Identity of M... (6 marks) 9 APW/0103/CHM1

67 7 3 When a sample of liquid, X, of mass g was vaporised, the vapour was found to occupy a volume of m 3 at a pressure of 110 kpa and a temperature of 473 K. (a) Give the name of the equation pv = nrt.... (1 mark) (b) Use the equation pv = nrt to calculate the number of moles of X in the sample and hence deduce the relative molecular mass of X. (The gas constant R = 8.31 J K 1 mol 1 ) Moles of X Relative molecular mass of X (4 marks) (c) Compound X, which contains carbon, hydrogen and oxygen only, has 38.7% carbon and 9.68% hydrogen by mass. Calculate the empirical formula of X (3 marks) (d) Using your answers to parts (b) and (c) above, deduce the molecular formula of X (1 mark) 9 Turn over APW/0103/CHM1

68 8 4 (a) The boiling point of H 2 O is 373 K and that of H 2 S is 212 K. (i) Name the strongest type of intermolecular attraction present in water. (ii) Name the strongest type of intermolecular attraction present in hydrogen sulphide. (iii) Explain why the boiling point of water is so much higher than that of hydrogen sulphide. (4 marks) (b) Define the term electronegativity (2 marks) (c) State and explain the trend in electronegativity down Group II from Be to Ba. Trend... Explanation (3 marks) (d) (i) Give the type of bonding present in BeCl 2 (ii) Give the type of bonding present in BaCl 2 (iii) Explain why the type of bonding is different in these two compounds. (3 marks) APW/0103/CHM1

69 9 (e) (i) Explain what is meant by the term amphoteric. Write two equations involving Be(OH) 2 to illustrate your answer. Explanation... Equation 1... Equation 2... (ii) In what way is this behaviour of Be(OH) 2 atypical of the behaviour of Group II metal hydroxides? (4 marks) 16 TURN OVER FOR THE NEXT QUESTION Turn over APW/0103/CHM1

70 10 5 There is a general trend in the values of the first ionisation energies of the elements Na to Ar. The first ionisation energies of the elements Al and S deviate from this trend. (a) Write an equation, including state symbols, to represent the process for which the energy change is the first ionisation energy of Na.... (2 marks) (b) State and explain the general trend in the values of the first ionisation energies of the elements Na to Ar. Trend... Explanation (3 marks) (c) State how, and explain why, the values of the first ionisation energies of the elements Al and S deviate from the general trend. How the values deviate from the trend... Explanation for Al Explanation for S (5 marks) 10 APW/0103/CHM1

71 11 SECTION B Answer both questions below in the space provided on pages 12 to 16 of this booklet. 6 (a) Ionisation is the first of the four main stages involved in obtaining the mass spectrum of a sample of gaseous titanium atoms. Explain how ionisation is achieved. Name the remaining three stages and, in each case, state how each stage is achieved. Explain why it would be difficult to distinguish between 48 Ti 2+ and 24 Mg + ions using a mass spectrometer. (10 marks) (b) State any differences and similarities in the atomic structure of the isotopes of an element. State the difference, if any, in the chemistry of these isotopes. Explain your answer. (4 marks) (c) The table below gives the percentage abundance of each isotope in the mass spectrum of a sample of titanium. m/z % abundance Define the term relative atomic mass of an element. Use the above data to calculate the value of the relative atomic mass of titanium in this sample. Give your answer to two decimal places. (4 marks) 7 (a) Predict the shapes of the SF 6 molecule and the AlCl 4 ion. Draw diagrams of these species to show their three-dimensional shapes. Name the shapes and suggest values for the bond angles. Explain your reasoning. (8 marks) (b) Perfume is a mixture of fragrant compounds dissolved in a volatile solvent. When applied to the skin the solvent evaporates, causing the skin to cool for a short time. After a while, the fragrance may be detected some distance away. Explain these observations. (4 marks) END OF QUESTIONS Turn over APW/0103/CHM1

72 Surname Other Names Leave blank Centre Number Candidate Number Candidate Signature General Certificate of Education June 2003 Advanced Subsidiary Examination CHEMISTRY CHM1 Unit 1 Atomic Structure, Bonding and Periodicity Wednesday 4 June 2003 Morning Session In addition to this paper you will require: a calculator. Number For Examiner s Use Mark Number Mark Time allowed: 1 hour Instructions Use blue or black ink or ball-point pen. Fill in the boxes at the top of this page. Answer all questions in Section A and Section B in the spaces provided. All working must be shown. Do all rough work in this book. Cross through any work you do not want marked. The Periodic Table/Data Sheet is provided on pages 3 and 4. Detach this perforated sheet at the start of the examination Information The maximum mark for this paper is 60. Mark allocations are shown in brackets. This paper carries 30 per cent of the total marks for AS. For Advanced Level this paper carries 15 per cent of the total marks. You are expected to use a calculator where appropriate. The following data may be required. Gas constant R = 8.31JK 1 mol 1 Your answers to the question in Section B should be written in continuous prose, where appropriate. You will be assessed on your ability to use an appropriate form and style of writing, to organise relevant information clearly and coherently, and to use specialist vocabulary, where appropriate. Advice You are advised to spend about 45 minutes on Section A and about 15 minutes on Section B. Total (Column 1) Total (Column 2) TOTAL Examiner s Initials APW/0203/CHM1

73 3 The Periodic Table of the Elements The atomic numbers and approximate relative atomic masses shown in the table are for use in the examination unless stated otherwise in an individual question. APW/0203/CHM1 I II III IV V VI VII He Helium Key 1.0 H Hydrogen Ne Neon F Fluorine O Oxygen N Nitrogen C Carbon B Boron relative atomic mass Li Lithium Li Lithium 3 atomic number 9.0 Be Beryllium Ar Argon Cl Chlorine S Sulphur P Phosphorus Si Silicon Al Aluminium Mg Magnesium Kr Krypton Br Bromine Se Selenium As Arsenic Ge Germanium Ga Gallium Zn Zinc Cu Copper Ni Nickel Co Cobalt Fe Iron Mn Manganese Cr Chromium V Vanadium Ti Titanium Sc Scandium Ca Calcium Na Sodium K Potassium Xe Xenon I Iodine Te Tellurium Sb Antimony Sn Tin In Indium Cd Cadmium Ag Silver Pd Palladium Rh Rhodium Ru Ruthenium Tc Technetium Mo Molybdenum Nb Niobium Zr Zirconium Y Yttrium Sr Strontium Rn Radon At Astatine Po Polonium Bi Bismuth Pb Lead Tl Thallium Hg Mercury Au Gold Pt Platinum Ir Iridium Os Osmium Re Rhenium W Tungsten Ta Tantalum Hf Hafnium La Lanthanum 57 * Ba Barium Ac Actinium Ra Radium Rb Rubidium Cs Caesium Fr Francium Lu Lutetium Yb Ytterbium Tm Thulium Er Erbium Ho Holmium Dy Dysprosium Tb Terbium Gd Gadolinium Eu Europium Sm Samarium Pm Promethium Nd Neodymium Pr Praseodymium Ce Cerium Th Thorium 90 * Lanthanides (260) Lr Lawrencium 103 (259) No Nobelium 102 (258) Md Mendelevium 101 (257) Fm Fermium 100 (252) Es Einsteinium Cf Californium Bk Berkelium Cm Curium Am Americium Pu Plutonium Np Neptunium U Uranium Pa Protactinium Actinides

74 4 Table 1 Proton n.m.r chemical shift data Type of proton δ/ppm RCH R 2 CH R 3 CH RCOCH ROCH RCOOCH ROH Table 2 Infra-red absorption data Bond Wavenumber/cm 1 C H C C C C C O C O O H (alcohols) O H (acids) APW/0203/CHM1

75 5 SECTION A Answer all questions in the spaces provided. 1 (a) (i) Complete the electronic configuration of aluminium. 1s 2... (ii) State the block in the Periodic Table to which aluminium belongs. (2 marks) (b) Describe the bonding in metals (2 marks) (c) Explain why the melting point of magnesium is higher than that of sodium (3 marks) (d) Explain how metals conduct electricity (2 marks) 9 Turn over APW/0203/CHM1

76 6 2 (a) Give the relative charge and relative mass of an electron. Relative charge... Relative mass... (2 marks) (b) Isotopes of chromium include 54 Cr and 52 Cr (i) Give the number of protons present in an atom of 54 Cr (ii) Deduce the number of neutrons present in an atom of 52 Cr (iii) Apart from the relative mass of each isotope, what else would need to be known for the relative atomic mass of chromium to be calculated? (3 marks) (c) In order to obtain a mass spectrum of a gaseous sample of chromium, the sample must first be ionised. (i) Give two reasons why it is necessary to ionise the chromium atoms in the sample. Reason 1... Reason 2... (ii) State what is adjusted so that each of the isotopes of chromium can be detected in turn. (iii) Explain how the adjustment given in part (c)(ii) enables the isotopes of chromium to be separated. (4 marks) APW/0203/CHM1

77 7 (d) (i) State what is meant by the term empirical formula. (ii) A chromium compound contains 28.4% of sodium and 32.1% of chromium by mass, the remainder being oxygen. Calculate the empirical formula of this compound. (4 marks) 13 TURN OVER FOR THE NEXT QUESTION Turn over APW/0203/CHM1

78 8 3 (a) A sample of ethanol vapour, C 2 H 5 OH (M r = 46.0), was maintained at a pressure of 100 kpa and at a temperature of 366 K. (i) State the ideal gas equation. (ii) Use the ideal gas equation to calculate the volume, in cm 3, that 1.36 g of ethanol vapour would occupy under these conditions. (The gas constant R = 8.31JK 1 mol 1 ) (5 marks) (b) Magnesium nitride reacts with water to form magnesium hydroxide and ammonia. (i) Balance the equation, given below, for the reaction between magnesium nitride and water. Mg 3 N 2 + H 2 O Mg(OH) 2 + NH 3 (ii) Calculate the number of moles, and hence the number of molecules, of NH 3 in g of ammonia gas. (The Avogadro constant L = mol 1 ) (4 marks) APW/0203/CHM1

79 9 (c) Sodium carbonate is manufactured in a two-stage process as shown by the equations below. NaCl + NH 3 + CO 2 + H 2 O NaHCO 3 + NH 4 Cl 2NaHCO 3 Na 2 CO 3 + H 2 O + CO 2 Calculate the maximum mass of sodium carbonate which could be obtained from 800 g of sodium chloride (4 marks) 13 TURN OVER FOR THE NEXT QUESTION Turn over APW/0203/CHM1

80 10 4 (a) Both HF and HCl are molecules having a polar covalent bond. Their boiling points are 293 K and 188 K respectively. (i) State which property of the atoms involved causes a bond to be polar. (ii) Explain, in terms of the intermolecular forces present in each compound, why HF has a higher boiling point than HCl. (4 marks) (b) When aluminium chloride reacts with chloride ions, as shown by the equation below, a co-ordinate bond is formed. AlCl 3 + Cl AlCl 4 Explain how this co-ordinate bond is formed (2 marks) APW/0203/CHM1

81 11 (c) Draw the shape of the PCl 5 molecule and of the PCl 4 + ion. State the value(s) of the bond angles. PCl 5 PCl 4 + Bond angle(s)... Bond angle(s)... (4 marks) 10 TURN OVER FOR THE NEXT QUESTION Turn over APW/0203/CHM1

82 12 SECTION B Answer the question below in the space provided on pages 12 to 16 of this booklet. 5 (a) The table below gives the melting point for each of the Period 3 elements Na Ar. Element Na Mg Al Si P S Cl Ar Melting point/ K In terms of structure and bonding, explain why silicon has a high melting point, and why the melting point of sulphur is higher than that of phosphorus. (7 marks) (b) Draw a diagram to show the structure of sodium chloride. Explain, in terms of bonding, why sodium chloride has a high melting point. (4 marks) (c) Give the conditions under which, if at all, beryllium and magnesium react with water. For any reaction that occurs, state one observation you would make and write an equation. (4 marks) END OF QUESTIONS APW/0203/CHM1

83 Surname Other Names Leave blank Centre Number Candidate Number Candidate Signature General Certificate of Education January 2004 Advanced Subsidiary Examination CHEMISTRY CHM1 Unit 1 Atomic Structure, Bonding and Periodicity Friday 9 January 2004 Morning Session In addition to this paper you will require: a calculator. Number For Examiner s Use Mark Number Mark Time allowed: 1 hour 1 2 Instructions Use blue or black ink or ball-point pen. Fill in the boxes at the top of this page. Answer all questions in Section A and Section B in the spaces provided. All working must be shown. Do all rough work in this book. Cross through any work you do not want marked. The Periodic Table/Data Sheet is provided on pages 3 and 4. Detach this perforated sheet at the start of the examination Information The maximum mark for this paper is 60. Mark allocations are shown in brackets. This paper carries 30 per cent of the total marks for AS. For Advanced Level this paper carries 15 per cent of the total marks. You are expected to use a calculator where appropriate. The following data may be required. Gas constant R = 8.31 J K 1 mol 1 Your answers to the question in Section B should be written in continuous prose, where appropriate. You will be assessed on your ability to use an appropriate form and style of writing, to organise relevant information clearly and coherently, and to use specialist vocabulary, where appropriate. Total (Column 1) Total (Column 2) TOTAL Examiner s Initials Advice You are advised to spend about 45 minutes on Section A and about 15 minutes on Section B. APW/0104/CHM1 CHM1