(2) Use the information to explain why graphite conducts electricity (3) (Total 5 marks)

Transcription

1 Q. (a) Copper is a metal. Explain how it conducts electricity. () (b) Graphite is a non-metal. Use the information to explain why graphite conducts electricity. (3) (Total 5 marks) Q. (a) The diagrams represent the atomic structures of two gases, hydrogen and helium. Hydrogen gas is made up of diatomic molecules (molecules with two atoms). Helium gas exists as single atoms. Page of 57

2 (i) How is a molecule of hydrogen formed from two hydrogen atoms? (You may use a diagram as part of your answer) () Why does helium exist only as single atoms? () (b) Hydrogen combines with carbon to form methane. Each molecule contains four hydrogen atoms strongly bonded to a carbon atom. Explain why methane has a low boiling point. () (Total 6 marks) Q3. (a) Write down the symbols for lithium... fluorine... () Page of 57

3 (b) The electronic structure of a lithium atom can be shown like this: In a similar way, complete this diagram to show the electronic structure of a fluorine atom. () (c) A lithium atom can lose one electron to form a lithium ion which can be written () + A fluorine atom can gain one electron to form a fluoride ion. Choose from the list the correct way to write the fluoride ion. (,6) + (,7) + (,7) - (,8) + (,8) Answer... () (Total 5 marks) Q4. The diagrams show the giant structures of sodium chloride and diamond. sodium chloride (melting point 80 C) diamond (melting point 4800 C) (a) The equation shows how sodium choride could be formed. Balance the equation. Na + Cl Na Cl () Page 3 of 57

4 (b) By reference to the detailed structure of sodium chloride explain fully why: (i) sodium chloride has a quite high melting point, () solid sodium chloride melts when it is heated strongly, () (iii) molten sodium chloride will conduct electricity. () (c) By reference to the detailed structure of diamond, explain why the melting point of diamond, is higher than that of sodium chloride. () (Total 7 marks) Page 4 of 57

5 Q5. (a) The diagrams below show the electronic structure of a magnesium atom and a magnesium ion. What is the charge on the magnesium ion?... () (b) Calcium bromide has the formula CaBr. What does this tell you about the ions in this compound? () (Total 4 marks) Q6. The diagram shows one molecule of the compound ammonia. Write down everything that the diagram tells you about each molecule of ammonia (Total 4 marks) Page 5 of 57

6 ## Atoms of calcium, phosphorus and fluorine are represented below, each with its mass number and proton number. (a) Use this information to complete the table. CALCIUM PHOSPHOROUS FLUORINE Number of protons in the nucleus 0 9 Number of neutrons in the nucleus 0 6 Number of electrons 5 9 (3) (b) Calcium and fluorine atoms can combine to form the compound calcium fluoride, CaF. The fluoride ion is represented by F. (i) Explain how the fluorine atom forms a fluoride ion () How is the calcium ion represented?... () (c) Phosphorus and fluorine form a covalent compound, phosphorus trifluoride. Complete the sentences below which are about this compound. Phosphorus trifluoride is made up of phosphorus and fluorine... These are joined together by sharing pairs of... to form phosphorus trifluoride.... (3) Page 6 of 57

7 (d) (i) Sodium chloride, an ionic compound, has a high melting point whereas paraffin wax, a molecular compound, melts easily. Explain why () Molten ionic compounds conduct electricity but molecular compounds are nonconductors, even when liquid. Explain why () (Total 4 marks) Q8. The diagram shows the elements in Group 4 of the periodic table. Page 7 of 57

8 Carbon is a non-metal and silicon is usually considered to be a non-metal. Tin and lead have all the usual properties of metals. Germanium has these properties: grey-white shiny solid melting point 937 C semi-conductor reacts with chlorine to form the chloride (GeCl 4 ) which is a liquid molecular compound germanium oxide reacts with acids to form a salt solution and water. It also reacts with alkalis. (a) With reference to their structure, explain why tin and lead are good conductors of electricity. (3) (b) Would you classify germanium as a metal or as a non-metal? Give your reasons. (3) (Total 6 marks) Page 8 of 57

9 Al + O Al O 3 () Q9. (a) Balance these chemical equations. (i) H + O H O () (b) Briefly explain why an unbalanced chemical equation cannot fully describe a reaction. () (c) Explain, as fully as you can, why a water molecule contains two hydrogen atoms but a hydrogen chloride molecule contains only one. (You may use a diagram in your answer if you wish). (3) (Total 7 marks) Q0. (a) The formula for ammonia is NH 3. What does the formula tell you about each molecule of ammonia? (3) Page 9 of 57

10 (b) Ammonia is used to make nitric acid (HNO 3 ). Calculate the formula mass (Mr) for nitric acid. (Show your working). (3) (Total 6 marks) Q. The questions which follow refer to the element hydrogen. (a) Draw a diagram to show the bonding in one molecule of hydrogen. () Page 0 of 57

11 (b) The table gives information about two compounds which contain hydrogen. Use the information in the table to explain why it is difficult to classify hydrogen as a metal or a non metal. (4) (Total 6 marks) Q. Sodium carbonate reacts with acids. (i) Complete the word equation. sodium carbonate + hydrochloric acid sodium chloride water () Name the salt produced if sodium carbonate reacts with dilute nitric acid. () (Total marks) Page of 57

12 Q3. (a) The chart shows the reactions of the metal calcium with water, oxygen and dilute hydrochloric acid. Name (i) solution A... solid B... (iii) gas C... (3) (b) The diagrams below show the electronic structure of an atom of calcium and an atom of oxygen. Describe fully what happens to its electrons when: (i) a calcium atom forms a calcium ion. State the charge on the calcium ion formed. (3) an oxygen atom forms an oxygen ion. State the charge on the oxygen ion formed. (3) Page of 57

13 (c) Calcium oxide is an ionic compound. Why do ionic compounds have high melting points? () (Total marks) Q4. (a) By reference to their structure, explain how the particles in a piece of metal are held together and how the shape of the metal can be changed without it breaking. (You may use a diagram in your answer.) (5) Page 3 of 57

14 (b) Explain why metals are good conductors of electricity and suggest why this conductivity increases across the periodic table from sodium to magnesium to aluminium. (4) (Total 9 marks) Q5. Chlorine will combine with the non-metal element, carbon, to form this molecular compound. (a) What is the type of bond in this molecule? () (b) Explain how these bonds are formed. (You may use a diagram). () (Total 3 marks) Page 4 of 57

15 Q6. Magnesium oxide is a compound, made up of magnesium ions and oxide ions. (a) What is the charge on each magnesium ion?... () (b) Explain how the magnesium ions get this charge. () (Total 3 marks) Q7. Part of a reactivity series is: (a) Carbon is used in blast furnaces to obtain iron and zinc from their oxides, but electrolysis has to be used to obtain aluminium from its oxide. Draw an arrow on the reactivity series above to show where carbon fits into the series. () (b) Predict the method of extraction used to obtain calcium from its ore and explain your answer. () Page 5 of 57

16 (c) The formula for zinc oxide is ZnO. Write a balanced equation for the extraction of zinc in the blast furnace. () (Total 5 marks) Q8. (a) The equation for the reaction that takes place when ammonium chloride is heated is: NH 4 Cl(s) NH 3 (g) + HCl (g) ammonium chloride ammonia hydrogen chloride The diagram shows how a teacher demonstrated this reaction. The demonstration was carried out in a fume cupboard. (i) Apart from the gases normally in the atmosphere, which two gases would be at X?... and... () Name the white solid that has formed at Y.... () (iii) Why was the demonstration carried out in a fume cupboard? () Page 6 of 57

17 (iv) Complete the four spaces in the passage. The chemical formula of ammonia is NH 3. This shows that there is one atom of... and three atoms of... in each... of ammonia. These atoms are joined by bonds that are formed by sharing pairs of electrons. This type of bond is called a... bond. (4) (b) Electrons, neutrons and protons are sub-atomic particles. (i) Complete the three spaces in the table. Name of sub-atomic particle Relative mass Relative charge () Which two sub-atomic particles are in the nucleus of an atom?... and... () (Total 0 marks) Q9. (a) The diagram shows part of the ionic lattice of a sodium chloride crystal. Page 7 of 57

18 (i) Complete the spaces in the table to give information about both of the ions in this lattice. Name of ion Charge () When it is solid, sodium chloride will not conduct electricity. However, molten sodium chloride will conduct electricity. Explain this difference () (iii) Complete the sentence. Sodium chloride conducts electricity when it is molten and when it is... () (b) The symbol for a calcium atom can be shown like this: (i) What is the mass number of this atom?... () What information is given by the mass number? () (c) Calcium burns in oxygen with a brick-red flame. The product is a white solid. It is calcium oxide and its formula is CaO. (i) Balance the chemical equation for the reaction. Ca(s) + O (g) CaO(s) () Page 8 of 57

19 Describe, in terms of electrons, what happens to a calcium atom when it becomes a calcium ion () (Total 0 marks) Q0. Part of the Periodic Table showing the symbols for the first twenty elements is given below. (a) Draw diagrams showing the arrangement of electrons (electronic structures) in: (i) an aluminium atom; a chlorine atom. () (b) (i) Use electronic structures to help you show why the formula of sodium oxide is Na O. (3) Page 9 of 57

20 State why the formation of sodium ions is classified as an oxidation () (Total 6 marks) Q. Ammonium nitrate and ammonium sulphate are used as fertilisers. (i) Which acid reacts with ammonia to form ammonium nitrate?... () Which acid reacts with ammonia to form ammonium sulphate?... () (iii) The reactions in (i) and are both exothermic. How can you tell that a reaction is exothermic? () Page 0 of 57

21 (iv) The reactions in (i) and are both examples of acid + base reactions. What is the name of the chemical change which takes place in every acid + base reaction?... () (Total 4 marks) Q. The drawing shows a container of a compound called magnesium chloride. (i) How many elements are joined together to form magnesium chloride?... () Magnesium chloride is an ionic compound. What are the names of its ions?... ions and... ions () (iii) How many negative ions are there in the formula for magnesium chloride?... () (iv) Complete the sentence. Ions are atoms, or groups of atoms, which have lost or gained.... () Page of 57

22 (v) Suggest three properties which magnesium chloride has because it is an ionic compound. Property Property Property (3) (Total 7 marks) Q3. (a) Atoms are made of sub-atomic particles. Complete the six spaces in the table. Name of sub-atomic particle Relative mass Relative charge Neutron (3) (b) Complete the spaces in the sentences. (i) The atomic number of an atom is the number of... in its nucleus and is equal to the number of... if the atom is not charged. () The mass number of an atom is the total number of... and... in its nucleus. () Page of 57

23 (c) The table gives information about the atoms of three elements. Number of electrons in: Name of element Chemical symbol st shell nd shell 3 rd shell Fluorine F 7 0 Neon Ne 8 0 Sodium Na 8 Two of these elements can react together to form a chemical compound. (i) What is the name and the formula of this compound? Name... Formula... () What type of bonding holds this compound together? () (iii) Explain, in terms of electron transfer, how the bonding occurs in this compound. () (Total 0 marks) ## In this question you will need to use the following information: Relative atomic masses: H ; O 6; Mg 4. The volume of one mole of any gas is 4 dm 3 at room temperature and atmospheric pressure. Page 3 of 57

24 The diagram shows a chemical reaction taking place in a conical flask. The balanced equation for this reaction is: Mg(s) + HCl(aq) MgCl (aq) + H (g) (a) Write a balanced ionic equation for this reaction.... () (b) Calculate the mass of magnesium required to produce 0.50 g of hydrogen. Show clearly how you work out your final answer and give the unit. Mass =... () (c) (i) Draw a diagram to show how the electrons are arranged in a hydrogen molecule. () What is the name of the type of chemical bond between the hydrogen atoms in a hydrogen molecule? () Page 4 of 57

25 (d) The chemical formula for hydrogen peroxide is H O. Calculate, to the nearest whole number, the percentage, by mass, of hydrogen in hydrogen peroxide. Show clearly how you work out your answer Percentage =... % () (Total 8 marks) Q5. Electrons, neutrons and protons are sub-atomic particles. (a) Complete the six spaces in the following table. Name of sub-atomic particle Relative mass Relative charge (3) (b) An aluminium atom has 3 electrons. How are these arranged in shells around the nucleus?... () (c) Chromium atoms have 4 protons and 8 neutrons. (i) How many electrons does each neutral chromium atom have? () What is the mass number of chromium? () (d) What change occurs to an atom which undergoes the process of reduction in a chemical reaction? () Page 5 of 57

26 (e) The diagram shows part of the ionic lattice of a sodium chloride crystal. Explain why the ions in this lattice stay in place (3) (Total 0 marks) Q6. (a) Every chemical element has a chemical symbol. Choose the correct chemical symbols from the box and complete the three spaces in the table. C Co Cu Fe I Ir Zn Zr Name of element Chemical symbol Copper... Iron... Zinc... (3) Page 6 of 57

27 (b) Give one use for each of the following metals. You should give a different use for each metal. Copper Iron... Zinc... (3) (c) Give four physical properties which metals usually have (4) (d) Metals usually form ionic compounds. Give one property of an ionic compound () Page 7 of 57

28 (e) The diagrams show two different atoms, atom A and atom B. Atom A Atom B (i) Complete the following sentence. For these two atoms to become ions one... would be transferred from atom... to atom.... () Atom A and atom B are from different elements. How can you tell this from their nuclei? () (Total 3 marks) Q7. (i) Complete the drawing to show the electron structure of a hydrogen fluoride molecule. Draw electrons as dots or crosses. () Page 8 of 57

29 Explain why hydrogen fluoride is a gas at room temperature. () (Total 3 marks) Q8. (a) A piece of lithium is placed on the surface of some water in a beaker. Hydrogen is given off. Lithium hydroxide is also formed. Write a word equation for this reaction. () (b) The diagram shows the structure of a molecule of methane. Write down everything that this diagram tells you about a methane molecule. To gain full marks in this question you should write your ideas in good English. Put them into a sensible order and use the correct scientific words. (4) (Total 6 marks) Page 9 of 57

30 Q9. The diagram shows the structure of diamond. (a) To gain full marks for this question you should write your ideas in good English. Put them into a sensible order and use the correct scientific words. Explain, as fully as you can, why diamond has a high melting point. (3) Page 30 of 57

31 (b) The diagram below shows the outer electron shells of five carbon atoms in the giant lattice of diamond. Carbon atom C forms bonds with each of the carbon atoms W, X, Y and Z. Draw the positions of all the electrons in the outer shells of each of carbon atoms C, W, X, Y and Z. (3) (Total 6 marks) Page 3 of 57

32 Q30. The diagram shows the structure of diamond. (a) To gain full marks for this question you should write your ideas in good English. Put them into a sensible order and use the correct scientific words. Explain, as fully as you can, why diamond has a high melting point. (3) Page 3 of 57

33 (b) The diagram below shows the outer electron shells of five carbon atoms in the giant lattice of diamond. Carbon atom C forms bonds with each of the carbon atoms W, X, Y and Z. Draw the positions of all the electrons in the outer shells of each of carbon atoms C, W, X, Y and Z. (3) (Total 6 marks) Page 33 of 57

34 M. (a) idea that copper has free electrons / electrons that move throughout the structure gains mark but in copper, electrons from the highest (occupied) energy level /outer shell, are free / can move throughout the structure gains marks (b) idea that in graphite, only three bonds are formed by each carbon atom for mark one outer electron (per atom), free to move for mark an electric current is a flow of (free) electrons* for mark (* this mark to be given in either (a) or (b) but not in both) 3 [5] M. (a) (i) idea that two hydrogen atoms share one pair of electrons linked by a covalent bond each then has two outer electrons / a full outer shell / two electrons in the highest (occupied) energy level ( marks may be awarded for a correct electron diagram i.e. with electrons on boundary of or within marked area). any two for mark each Page 34 of 57

35 idea that helium atoms do not give / take / share electrons / react because the (outer) shell / orbit is full or highest (occupied) energy level is full (but not just contains two electrons ) for mark each (b) idea that the (attractive) forces between molecules are weak (not bonds between atoms) so little energy is required / it is easy for molecules to escape from the liquid* / escape from other molecules* (allow evaporate / change into a gas) for mark each [6] M3. (a) lithium = Li (ignore mass / atomic numbers) fluorine = F (do not allow if case is incorrect) for mark each (b) (allow or o for electrons) (allow any positions for the seven electrons added provided they are on the outer ring) for mark (c) (,8) + or (,7) (brackets not required) gains mark but (,8) gains marks [5] Page 35 of 57

36 M4. (a) Na + Cl NaCl allow Na + Cl for mark (allow Na + ½Cl Na Cl) (b) (i) idea that it has strong (attractive) forces/bonds between ions / charged particles for mark (not..it has a rigid structure - this defines a solid or...particles close together they are in a liquid) ideas that there is increased vibration of ions / particles on heating ions have sufficient energy to overcome attractive forces / to break out of the rigid structure / to move about (must be in terms of increased energy of particles lions) each for mark (iii) ions can go to electrodes / ions are free to move for mark [do not credit ions carry charges ] (c) ideas that it has stronger attractive forces between atoms/particles (not ions ) each carbon atom forms covalent bonds with neighbouring atoms each for mark [7] Page 36 of 57

37 M5. (a) positive / + / gains mark but + / ++ / + (b) Ideas that: gains marks Ca + Br - [Do not disqualify for "bromine" ions] Ions / They are in the ratio : any two for mark each [4] M6. idea that contains nitrogen atoms contains hydrogen atoms atoms are chemically bonded NOT linked/joined ratio of one nitrogen to three hydrogen (atoms) formula of ammonia is NH 3 for mark each [4] M7. (a) Calcium Phosphorus Fluorine No of protons 5 No of neutrons 0 No of electrons 0 for mark each 3 (b) (i) gain of electron(s) from (atoms) (of) calcium for mark Page 37 of 57

38 Ca + gains mark (c) but superscript only Ca + / Ca ++ gains marks atoms electrons molecule(s) not compound each for mark 3 (d) (i) ideas that ionic strong forces between ions molecular weak forces between molecules each for mark ideas that ionic ions/charged particles are free to move molecular -molecules do not carry a charge each for mark [4] ## (a) idea that some of the outer electrons of the atoms are free to move can move anywhere across the (giant) structure the flow of electricity is a stream of electrons each for mark or electrons carry a (negative electrical) charge 3 Page 38 of 57

39 (b) metal element [shiny] appearance [high] melting point forms an oxide that reacts with acids to make a salt of these for mark non metal element forms an oxide that reacts with alkalis with chlorine forms a molecular chloride of these for mark semi-conductor suggests in between this, or any other for further mark [NB Maximum of for arguing metal/non-metal only] Under each head wrong reason maximum of available wrong reasons no mark available] 3 [6] M9. (a) (i) H + O H O (allow H + ½O H O) both circled for mark 4 A + 3 O A O 3 all circled for mark (b) idea that: must end up with the same number of atoms otherwise matter is shown to be lost/gained doesn t show correct amount of each element/compared each for mark (c) idea that: oxygen has electrons short in outer shell ) in words or chlorine has electron short in outer shell ) indicated on diagram (shared pair/covalent bond with) hydrogen atom supplies one further electron* *(but do not allow hydrogen gives away electron or ionic bond) for mark each 3 [7] Page 39 of 57

40 M0. (a) reference to hydrogen (atoms) ) nitrogen (atoms) ) but not molecules each for mark ratio of N to 3H atoms for further mark or nitrogen atom and 3 hydrogen atoms (ignore any incorrect statements about nature of bonding) 3 (b) evidence of H = N = 4 O = 6 gains mark but H = N = 4 O = 6 3 or 48 gains marks but 63 gains 3 marks 3 [6] M. (a) correct representation of atom of hydrogen e.g. gains mark but correct representation of molecule of hydrogen e.g. or H-H gains marks Page 40 of 57

41 (b) idea that: hydrogen/metals form positive ions/lose electrons gains mark but hydrogen and the metals form positive ions/lose electrons gains marks hydrogen/non-metals form covalent bonds/share electrons gains mark but hydrogen and the non-metals form covalent bonds/share electrons gains marks 4 [6] M. (i) carbon dioxide (allow CO ) for mark sodium nitrate (accept correct formula) for mark [] M3. (a) (i) A calcium hydroxide/limewater/ca(oh) not CaOH B calcium oxide/quicklime/cao (iii) C hydrogen/h (accept correct formulae)/ not H /H each for mark 3 (b) (i) idea that electrons are lost (by the calcium atom) gains mark but two electrons are lost (by the calcium atom)/lose outer electrons to get full shell gains marks calcium ions are + for mark Page 4 of 57

42 electrons are gained (by the oxygen atom) gains mark but two electrons are gained (by the oxygen atom)/gain electrons to get full outer shell gains marks oxygen ions are for mark 6 (b) (i) needs: electron loss/gain number () charge (+/ ) (c) idea that they are held together by many/strong forces/bonds a lot of energy/high temperature is required to break these forces/bonds each for mark [] ## (a) (b) Idea that the electrons do not belong to specific atoms/delocalised electrons [credit if done on appropriate diagram] metal atoms form positive ions the attraction which exists between particles with opposite charges, holds the metal together no specific bonds exist between adjacent atoms/ions atoms/ions can slide over each other so allowing metals to bend each for mark 5 some electrons in the structure are delocalised/free to move for mark these free electrons carry the electric current for mark from left to right across the period, atoms of elements have more free electrons gains mark but from left to right across the period, atoms of elements have more free electrons because they have more electrons in the outer shells gains marks 4 [9] Page 4 of 57

43 ## (a) covalent bonds for mark (b) any reference to shared electrons gains mark but idea that bond is shared pair of electrons gains marks [3] ## (a) positive for mark (b) any reference to loss of electrons for mark reference to charge being + (in (a)) or to loss of electrons (in (b)) for mark [3] M7. (a) This part was not marked (b) electrolysis because calcium is more reactive (than aluminium or carbon) OR in a blast furnace accept it is more reactive or very reactive because calcium is less reactive (than carbon or lower) Page 43 of 57

44 (c) any equation from mark for correct formulae mark for balancing ZnO + C Zn + CO ZnO + CO Zn + CO ZnO + C Zn + CO [5] M8. (a) (i) ammonia and hydrogen chloride both required either order accept formulae if correct in every detail ammonium chloride / NH 4 Cl do not credit ammonia chloride (iii) the fumes / gases / are poisonous / toxic or ammonia and hydrogen chloride are poisonous / toxic / lethal accept just ammonia is poisonous / toxic accept just hydrogen chloride is poisonous / toxic accept vapour is poisonous / toxic do not credit just fumes are dangerous or harmful (iv) nitrogen do not credit N/N hydrogen do not credit H/H molecule do not credit compound or mole covalent accept single / molecular Page 44 of 57

45 (b) (i) proton neutron electron either all three correct or one or two correct however do not credit a response which is repeated protons and neutrons both required in either order [0] M9. (a) (i) sodium... positive or + both required chloride... negative or both required do not credit chlorine ions not free (to move) in solid crystal / lattice ions are free to move when sodium chloride is molten or ions are mobile do not credit when ions are molten allow 'particles' for ions () mark do not credit electrons etc (iii) dissolved in water or in aqueous solution accept in solution accept in water or when a gas/ vapour or solid it will not (b) (i) 40 (total) number of protons and neutrons (in the nucleus) (c) (i) Ca + O -+ CaO accept any n : n : n ratio do not credit if any other change has been made Page 45 of 57

46 any two from electron(s) is / are lost from the outer shell / orbit / ring or from the shell furthest the nucleus or from the 4th shell two / both (electrons are lost) accept two electrons are lost for ()marks accept both electrons are lost from the atom for () mark [0] M0. (a) (i) rings of, 8 and 3 electrons credit, 8, 3 pay particular attention to the outer shell in diagrams rings of, 8 and 7 electrons credit, 8, 7 pay particular attention to the outer shell in diagrams (b) (i) labels not required on atoms charges need to be shown on ions reference to outer shell is required otherwise a maximum of two marks structure of atoms/ions marks (ring of, 8, for sodium) or the outer shell of sodium only contains electron credit, 8, or an ion, 8 or two circles and electron in outer shell (ring of, 6 for oxygen) or outer shell only contains 6 electrons credit, 6 or an ion, 8 or two circles transfer of electrons mark two sodiums needed to supply two outer electrons to oxygen to complete the (one oxygen's) outer shell award maximum of two marks if a covalent structure is given credit two rings of electrons for sodium showing outer electrons transferring to outer shell of one oxygen for three marks do not accept diagrams showing overlapping rings for third mark Page 46 of 57

47 loses an electron credit atoms lose electrons or oxygen takes the electron ignore oil rig [6] M. NOTE In this question and throughout the Paper, if the name of a chemical is asked for, then the formula is acceptable only if it is correct in every detail. If the name is correct and the candidate has tried to be helpful by giving, in addition, an incorrect version of the formula, then this is acceptable provided it does not lead to ambiguity. (i) nitric (acid) accept HN0 3 sulphuric (acid) accept H SO 4 (iii) heat given out or temperature rise or energy given out or steam do not credit just use a thermometer do not credit just 'change in temperature' (iv) neutralisation accept neutralise accept neutral accept formation of salt or water do not credit exothermic [4] Page 47 of 57

48 M. (i) two or magnesium and chloride either order not positive / negative do not credit chlorine accept Mg ++ and Cl - do not credit just Mg and Cl accept cation(s) and anion(s) (iii) (iv) electrons accept charges (v) any three from (is a) giant structure/lattice structure crystalline / hard accept just 'crystals(s) high melting point / solid high boiling point conductor (of electricity) when dissolved in water or conductor (of electricity) when ions are free to move conductor (of electricity) when molten soluble in water 3 [7] M3. (a) both correct in each row electron... () allow negative... 0 allow neutral or none proton...+ () allow positive Page 48 of 57

49 (b) (i) protons...electrons both correct in correct order protons...neutrons both correct in either order (c) (i) sodium fluoride do not credit sodium fluorine NaF must be correct in every detail do not credit NAF and the like ionic accept ion (bonding) do not credit ironic or iron (bonding) (iii) electron transferred from sodium to fluorine accept electron transferred from metal to non-metal either positive sodium ion and negative fluoride ion or correctly identified by the symbols Na+ and F- accept positive sodium ion and negative fluorine ion or attracted because have opposite charge(s) or (atoms/ions) form an (ionic) lattice or (atoms/ions) form a crystal e.g. or both marks may be gained by a suitable dot and cross diagram [0] M4. (a) Mg + H + Mg + + H * reactants correct in every detail * products correct in every detail if the spectator ions are sown then () mark should be credited but only if they are shown correctly on both sides e.g. Mg + H + + CI - Mg + + CI - + H Page 49 of 57

50 (b) 4 (parts) of magnesium (parts) of hydrogen or equally clear working (so) 6 grams/g (are needed) unit required (c) (i) two (and no more) atoms shown to be sharing their single electrons examples do not credit if anything which contradicts the impression that these are hydrogen atoms (single) covalent (bond) (d) ( 00) = 6 (just 6 is worth () mark) 00 = 6 or similar is (0) do not credit and the like [8] M5. (a) proton + () both required neutron both required electron () both required 3 (b).8.3 accept words or diagram to this effect (c) (i) 4 5 Page 50 of 57

51 (d) any one of gains one or more electrons accept gains an electron becomes an anion do not credit becomes an ion becomes a negative ion (e) sodium ions have a (single) positive charge and chloride ions have a (single) negative charge do not credit chlorine ions but allow this error to be carried forward ions with opposite charge are attracted (to each other) or the positive ions and the negative ions are attracted (to each other) or the sodium ions and the chloride ions are attracted (to each other) (positive and negative) ions are arranged alternatively (in each direction or dimension) or ions with the same charge are repelled (by each other) no mark for just ionic bonds [0] M6. (a) Cu Fe Zn (b) one significant use for each metal do not credit vague answers such as in experiments and the like do not credit the same use more than once copper examples: do not credit diet supplement Page 5 of 57

52 coins or coinage (metal) or make alloys or bronze or brass conducting electricity or (electrical) wiring or motors or cables (domestic) (water) pipes heat exchangers roofing steam pipes stills or cooking utensils accept any specified still e.g. whisky still bracelets or rings iron or steel answers examples: do not credit diet supplement * access-hole covers (sometimes known as manhole covers) * catalyst (in the production of ammonia) * manufacture of steel(s) or in the basic oxygen process * named vehicle or transport or machinery or railings any other uses for iron and steel can be credited provided that the use is clear so, for example, bridges and railway lines would be creditworthy but do not credit buildings and transport which are too vague zinc examples: do not credit diet supplement * brass manufacture * die castings * rust prevention * to galvanise (iron or steel) or (as a) protective coating * battery casing (c) any four general properties of do not credit hard or strong or tough or magnetic are not brittle accept can be bent (into shape) or flexible can be hammered (into shape) accept are malleable can be stretched (into shape) accept are ductile Page 5 of 57

53 (good) conductors of heat accept just (good) conductor once only (good) conductors of electricity high boiling points high density or heavy or dense high melting points ringing sound when struck accept sonorous solids (at room temperature) accept shiny (when polished) or silvery 4 (d) any one of do not credit electron references * (good) conductor (of electricity) when molten or liquid accept dissolves in water or crystalline * (good) conductor (of electricity) when in aqueous solution accept (good) conductor (of electricity) when dissolved in water * high melting point or high boiling point do not credit just solid (e) (i) electron from A to B both parts required different numbers of protons accept different atomic numbers do not credit references to neutrons [3] M7. (i) Page 53 of 57

54 weak forces accept weak bonds between molecules / intermolecular reject intramolecular [3] M8. (a) LHS lithium + water accept Li and H O accept hydrogen oxide for water RHS hydrogen + lithium hydroxide accept H and LiOH ignore attempts at balancing ignore charges (b) Quality of written communication One mark for the correct use of any three of the terms atom, covalent, bond(ing), saturated, hydrocarbon or alkane any three from: one / the carbon (atom) reject molecules once four hydrogen (atoms) shape / properties neutral CH 4 hydrocarbon saturated / single bond covalent bond / shared electrons alkane reject ionic bond 3 [6] Page 54 of 57

55 M9. (a) Quality of written communication: All scientific words used correctly (covalent, bonds, atoms) any two from large numbers of covalent bonds allow giant lattice / structure between atoms do not accept between molecules (covalent) bonds strong accept need much energy to break (b) each carbon has 4 electrons one shared pair four shared pairs [6] Page 55 of 57

56 M30. (a) Quality of written communication: All scientific words used correctly (covalent, bonds, atoms) any two from large numbers of covalent bonds allow giant lattice / structure between atoms do not accept between molecules (covalent) bonds strong accept need much energy to break (b) each carbon has 4 electrons one shared pair four shared pairs [6] Page 56 of 57

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