Ionic and covalent,metallic bonding

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element conduct electricity? Tick one box. It has delocalised electrons It contains hexagonal rings It has weak forces between the layers It has ionic bonds (d) Figure 2 shows the structure of an alloy. Figure 2 Metal X Metal Y Explain why this alloy is harder than the pure metal Y. Page 3 (1) (1) Key The ball and stick model is not a true representation of the structure of potassium sulfide. Give one reason why. H Potassium ion Sulfide ion (c) Sulfur can also form covalent bonds. Complete the dot and cross diagram to show the covalent bonding in a molecule of hydrogen sulfide. Show the outer shell electrons only. S H (d) Calculate the relative formula mass (M₁) of aluminium sulfate Al₂(SO4)3 Relative atomic masses (A,): oxygen = 16; aluminium = 27; sulfur = 32 Page 3 (1) (2) (c) Figure 2 shows the displayed formulae for the reaction of ethene with bromine. Figure 2 H Energy in kJ/mole C=C H H 612 H H The bond enthalpies and the overall energy change are shown in the table below. + Br Br C-H 412 C-C Bond energy 348 Figure 3 H C=C + CI-CI H H H H-C-C-H C-Br 276 Use the information in the table above and Figure 2 to calculate the bond energy for the Br-Br bond. Page 3 Br Br (d) Figure 3 shows the reaction between ethene and chlorine and is similar to the reaction between ethene and bromine. Overall energy change -95 . kJ/mole HH H-C-C-H CI CI "The more energy levels (shells) of electrons an atom has, the weaker the covalent bonds that it forms." (3) (e) What percentage of the atoms in the alloys are atoms of X? (f) What type of substance is an alloy? Tick one box. Compound Element Mixture Page 4 (2) (2) (1) (Total 11 marks) Use the above statement to predict and explain how the overall energy change for the reaction of ethene with chlorine will differ from the overall energy change for the reaction of ethene with bromine. Page 4 (6) (Total 14 marks) (e) Covalent compounds such as hydrogen sulfide have low melting points and do not conduct electricity when molten. Draw one line from each property to the explanation of the property. Property Low melting point Relative formula mass= Does not conduct electricity when molten Explanation of property Page 4 Electrons are free to move There are no charged particles free to move lons are free to move Weak intermolecular forces of attraction Bonds are weak Bonds are strong (2) (f) Ionic compounds such as potassium sulfide have high boiling points and conduct electricity when dissolved in water. Draw one line from each property to the explanation of the property. Property High boiling point Conduct electricity when molten Page 5 Explanation of property Electrons are free to move There are no charged particles free to move lons are free to move Weak intermolecular forces of attraction Bonds are weak Bonds are strong (2) (2) (Total 14 marks) Q2. The structures of four substances, A, B, C and D, are represented in Figure 1. Figure 1 (a) (b) B Use the correct letter, A, B, C or D, to answer each question. (i) Which substance is a gas? (ii) (iii) Which substance is a liquid? Which substance is an element? (iv) Which substance is made of ions? Figure 2 shows the bonding in substance C. C Page 5 (1) (1) (1) (1) Q2.This question is about copper. (a) Copper can be extracted by smelting copper-rich ores in a furnace. The equation for one of the reactions in the smelting process is: Cu₂S(s) + O₂(g) 2 Cu(s) + SO₂(g) Explain why there would be an environmental problem if sulfur dioxide gas escaped into the atmosphere. (b) The impure copper produced by smelting is purified by electrolysis, as shown below. Negative electrode (cathode) pure copper (i) d.c. power supply Positive electrode (anode) impure copper Copper atoms are oxidised at the positive electrode to Cu²+ ions, as shown in the half equation. Electrolyte Page 5 Cu(s) Cu²+ (aq) + 2e™ How does the half equation show that copper atoms are oxidised? (2) (1) (i) What is the formula of substance C? SO₂ Figure 2 Oo Draw a ring around the correct answer. OXOX SO² delocalised electrons are covalent S₂O (ii) Use the correct answer from the box to complete the sentence. shared OXOX (iii) What is the type of bonding in substance C? Draw a ring around the correct answer. ionic When a sulfur atom and an oxygen atom bond to produce substance C, -**- Page 6 O transferred metallic (1) (1) (1) (Total 7 marks) Q2. This question is about magnesium. (a) (i) The electronic structure of a magnesium atom is shown below. Use the correct answer from the box to complete each sentence. electrons neutrons Nucleus 2+ protons The nucleus contains protons and The particles with the smallest relative mass that move around the nucleus are called Atoms of magnesium are neutral because they contain the same number of electrons and (ii) A magnesium atom reacts to produce a magnesium ion. Which diagram shows a magnesium ion? Tick (✓) one box. Page 6 shells ** Ņ (3) (1) (c) (ii) The Cu²+ ions are attracted to the negative electrode, where they are reduced to produce copper atoms. Write a balanced half equation for the reaction at the negative electrode. (iii) Suggest a suitable electrolyte for the electrolysis. Copper metal is used in electrical appliances. Describe the bonding in a metal, and explain why metals conduct electricity. (d) Soil near copper mines is often contaminated with low percentages of copper compounds. Phytomining is a new way to extract copper compounds from soil. Page 6 (1) (1) (4) Describe how copper compounds are extracted by phytomining. (e) A compound in a copper ore has the following percentage composition by mass: 55.6% copper, 16.4% iron, 28.0% sulfur. Calculate the empirical formula of the compound. Relative atomic masses (A.): S = 32; Fe = 56; Cu = 63.5 You must show all of your working. Empirical formula = Page 7 (3) (4) (Total 16 marks) (b) Magnesium and dilute hydrochloric acid react to produce magnesium chloride solution and hydrogen. Mg(s) + 2 HCl(aq) MgCl₂(aq) + H₂(g) (i) State two observations that could be made during the reaction. 1 2 In this question you will be assessed on using good English, organising information clearly and using specialist terms where appropriate. Describe a method for making pure crystals of magnesium chloride from magnesium and dilute hydrochloric acid. In your method you should name the apparatus you will use. You do not need to mention safety. Page 7 (2) (6) (Total 12 marks) Q3. This question is about salts. (a) (b) Salt (sodium chloride) is added to many types of food. Sodium chloride is produced by reacting sodium with chlorine. sodium + chlorine The diagram shows what happens to atoms of sodium and chlorine in this reaction. The dots (•) and crosses (x) represent electrons. Only the outer electrons are shown. Na O-DO Describe, in terms of electrons, what happens when a sodium atom reacts with a chlorine atom to produce sodium chloride. sodium chloride Lack of iodine can affect the learning ability of children. One idea is that salt (sodium chloride) should have iodine added. (i) lodine consists of simple molecules. What is a property of substances that have simple molecules? Tick (✓) one box. Have no overall electric charge Page 7 (3) Q3. This question is about metals and alloys. (a) Explain how electricity is conducted in a metal. To gain full marks you must include a description of the structure and bonding of a metal. (b) Describe how the structure of an alloy is different from the structure of a pure metal. (c) Alloys are used to make dental braces and coins. (i) Nitinol is an alloy used in dental braces. Why is Nitinol used in dental braces? (ii) Suggest one reason why coins are not made of pure copper. Page 8 (4) (2) (1) (ii) Have high boiling points Have giant covalent structures Which one of the following questions cannot be answered by science alone? Tick (✓) one box. How much sodium chloride is in food? What harm does a lack of iodine do? Should iodine be added to salt in food? Give one reason why this question cannot be answered by science alone. (c) A student produced the salt ammonium nitrate by adding an acid to ammonia solution. (i) Name the acid used. (ii) Use the correct answer from the box to complete the sentence. an acid an alkali Page 8 a salt (1) (2) (1) Q3.This question is about ethanol. (a) Ethanol is produced by the reaction of ethene and steam: C₂H₂ + H₂O (b) (i) Figure 1 shows the energy level diagram for the reaction. Figure 1 Energy C₂H4 + H₂O C₂H,OH (ii) A catalyst is used for the reaction. How does the energy level diagram show that the reaction is exothermic? C₂H5OH Explain how a catalyst increases the rate of the reaction. Figure 2 shows the displayed structure of ethanol. Page 8 (1) (2) (d) Do not give cost as a reason. (iii) Some coins are made from an alloy of aluminium. Complete the sentence. Aluminium is manufactured by the electrolysis of a molten mixture of cryolite and (iv) Banks keep coins in poly(ethene) bags. These bags are made from low density poly(ethene). High density poly(ethene) can also be made from the same monomer. How can the same reaction produce two different products? Give two reasons why instrumental methods of analysis are used to detect impurities in metals. Page 9 (1) (1) (1) (1) (Total 11 marks) (c) Figure 2 H H 1 T H-C-C-0-H H H Complete the dot and cross diagram in Figure 3 to show the bonding in ethanol. Show the outer shell electrons only. H H H A student burned some ethanol. Figure 3 Figure 4 shows the apparatus the student used. Figure 4 His results are shown in Table 1. H Page 9 H Thermometer Glass beaker -50g of water O Spirit burner containing ethanol (i) The student recorded the temperature of the water before and after heating. H (2) (d) Ammonia solution (ammonium hydroxide) is (iii) The student added a few drops of a solution which changed colour when the reaction was complete. (i) Complete the sentence. The solution added is an Farmers buy solid ammonium nitrate in poly(ethene) sacks. How is solid ammonium nitrate made from a solution of ammonium nitrate? Tick (✓) one box. Crystallisation Decomposition Electrolysis (ii) Why do farmers use ammonium nitrate on their fields? (iii) The properties of poly(ethene) depend on the reaction conditions when it is made. State one reaction condition that can be changed when making poly(ethene). Page 9 (1) (1) (1) (1) (1) (Total 12 marks) Q4.A student investigated the conductivity of different concentrations of sodium chloride solution. The student set the apparatus up as shown in Figure 1. ● The student measured the conductivity of the pure water with a conductivity meter. The reading on the conductivity meter was zero. (a) The student: Number of drops of sodium chloride solution added 0 added sodium chloride solution one drop at a time stirred the solution recorded the reading on the conductivity meter. 1 The student's results are shown in the table below. 2 Figure 1 d.c. power supply 3 4 Conductivity meter 5 -Pure water Relative conductivity of solution 0 Electrodes 100 Page 10 120 310 400 510 Temperature before heating Temperature after heating Table 1 20.7 °C 35.1 °C Calculate the energy used to heat the water. Use the equation Q = mx cx AT The specific heat capacity of water = 4.2 J/g/°C Energy used = Table 2 shows the mass of the spirit burner before the ethanol was burned and after the ethanol was burned. Table 2 Mass of spirit burner before ethanol was burned Mass of spirit burner after ethanol was burned Page 10 72.80 g 72.10 g Calculate the number of moles of ethanol (C₂H,OH) that were burned. Relative atomic masses (A.): H = 1; C = 12; 0 = 16 (3) Q4. This question is about electrolysis. (a) Metal spoons can be coated with silver. This is called electroplating. (b) Suggest one reason why spoons are electroplated. When sodium chloride solution is electrolysed the products are hydrogen and chlorine. (i) What is made from chlorine? Tick (✓) one box. Bleach Fertiliser Soap (ii) Sodium chloride solution contains two types of positive ions, hydrogen ions (H*) and sodium ions (Na'). Why is hydrogen produced at the negative electrode and not sodium? Tick (✓) one box. Hydrogen is a gas. Page 10 (1) (1) (d) (iii) Calculate the energy released in joules per mole. You should assume that all the energy from the ethanol burning was used to heat the water. Name Number of moles burned = Structure The names, structures and boiling points of ethanol and two other alcohols are shown in Table 3. Boiling point in °C Methanol H Energy = H 65 Table 3 Ethanol HIC-O-HH-C-C-0-H H H H H J/mole 78 Page 11 H HICIH Propanol H H H-C-C-C-0-H 1 H 97 H Use your knowledge of structure and bonding to suggest why the boiling points increase as the number of carbon atoms increases. (3) (1) 800 (ii) 700 600 500- Relative conductivity 400 of solution (i) The student plotted the results on the grid shown in Figure 2. Plot the four remaining results. Draw a line of best fit, ignoring the anomalous result. Figure 2 300- 200- 100- 6 0 7 8 15 590 One of the points is anomalous. 710 Page 11 800 Number of drops of sodium chloride added (3) Hydrogen is less reactive than sodium. Hydrogen ions move faster than sodium ions. (iii) Hydrogen and chlorine can be used to produce hydrogen chloride. The diagrams in Figure 1 show how the outer electrons are arranged in an atom of hydrogen and an atom of chlorine. Tick (✓) one box. Hydrogen atom H Covalent Figure 1 Complete Figure 2 to show how the outer electrons are arranged in a molecule of hydrogen chloride (HCI). H Chlorine atom (iv) What is the type of bond in a molecule of hydrogen chloride? Page 11 CI Figure 2 (1) (1) (c) lonic = A Metallic (v) Why is hydrogen chloride a gas at room temperature (20 °C)? Tick (✓) two boxes. Hydrogen chloride has a low boiling point. Hydrogen chloride has a high melting point. Hydrogen chloride is made of simple molecules. Hydrogen chloride does not conduct electricity. Hydrogen chloride has a giant structure. Aluminium is produced by electrolysis of a molten mixture of aluminium oxide and cryolite. This is shown in Figure 3. Page 12 (1) (2) Suggest one error that the student may have made to cause the anomalous result. (iii) The student wanted to compare the conductivity of sodium chloride solution with the conductivity of potassium chloride solution. State one variable he should keep constant when measuring the conductivity of the two solutions. (b) (i) Explain, in terms of bonding, why pure water does not conduct electricity. (ii) Explain why sodium chloride solution conducts electricity. (iii) After he had added sodium chloride solution, the student noticed bubbles of gas at the negative electrode. Page 12 (1) (1) (2) (2) Page 12 (3) (Total 15 marks) Complete the sentence. The gas produced at the negative electrode is Page 13 (1) (Total 10 marks) Molten cryolite containing aluminium oxide (i) Name a gas produced at the positive electrode. Figure 3 Ⓒ (ii) Aluminium ions move to the negative electrode. Explain why. Tick (✓) one box. 02 02- 02- A13+ A13+ Combustion Oxidation (iii) At the negative electrode, the aluminium ions gain electrons to produce aluminium. What is this type of reaction called? Gas forms at the positive electrode Page 13 Aluminium forms at the negative electrode (1) (2) Q5.In this question you will be assessed on using good English, organising information clearly and using specialist terms where appropriate. Explain why chlorine (Cl₂) is a gas at room temperature, but sodium chloride (NaCl) is a solid at room temperature. Chlorine Extra space CICI Sodium chloride Include a description of the bonding and structure of chlorine and sodium chloride in your answer. -Chloride ion (CH) -Sodium ion (Na*) Page 14 (Total 6 marks) (d) Reduction (iv) Aluminium has layers of atoms, as shown in Figure 4. Figure 4 Complete the sentence. Metals can be bent and shaped because the layers of atoms can ...... Aluminium atom Electrodes used in the production of aluminium are made from graphite. (i) Which diagram, A, B or C, shows the structure of graphite? A B The structure of graphite is shown in diagram Page 14 (1) (1) (1) (ii) The temperature for the electrolysis is 950 °C. Use the correct answer from the box to complete the sentence. cross links a giant ionic lattice strong covalent bonds The graphite does not melt at 950 °C because graphite has. Page 15 (1) (Total 14 marks) Q5.This question is about diamonds. Draw a ring around the correct answer to complete each sentence. (a) Diamonds are found in meteorites. (i) Meteorites get very hot when they pass through the Earth's atmosphere, but the diamonds do not melt. (ii) high Diamond has a low very low melting point. Most diamonds found in meteorites are nanodiamonds. A nanodiamond contains a few hundred thousand million. (b) Diamonds are used for the cutting end of drill bits. Page 16 Diamonds can be used for drill bits because they are atoms hard. shiny. soft. (c) The figure below shows the arrangement of atoms in diamond. (1) (1) (1) (i) (ii) (iii) carbon Diamond is made from nitrogen oxygen Each atom in diamond is bonded to covalent Page 17 atoms. three four five other atoms. (1) (1) (iv) Diamond has a giant In diamond all none some ionic metallic structure. of the atoms are bonded together. Q6. The diagram shows a small part of the structure of silicon dioxide. (a) Use the diagram above to answer the question. Draw a ring around the correct answer to complete each sentence. In silicon dioxide, each silicon atom is bonded with Page 18 Key O Oxygen atom Silicon atom two three oxygen atoms. (1) (1) (Total 7 marks) (b) (c) The bonds in silicon dioxide are ionic. covalent. metallic. Ⓒ Oleksiy Mark/iStock Silicon dioxide is used as the inside layer of furnaces. Suggest why. Nanowires can be made from silicon dioxide. Draw a ring around the correct answer to complete the sentence. Page 19 four brittle. (2) (1) The word 'nano' means the wires are very Page 20 thick. thin. (1) (Total 4 marks) Q7.The picture shows a student filling in a multiple choice answer sheet using a pencil. Layers are only held together very weakly Atoms in the layers are strongly bonded together 1+1= (a) 4/4 co 13 CAJ CB3 C CCE The pencil contains graphite. Graphite rubs off the pencil onto the paper. Diagrams 1 and 2 show how the atoms are arranged in graphite. 14 15 CA CBD CC Co Ⓒ Cihan Ta?k?n/iStock Page 21 DE Diagram 1 Layers of atoms Diagram 2 Use the diagrams to help you explain why graphite can rub off the pencil onto the paper. (2) (b) Draw a ring around the type of bond which holds the atoms together in each layer. covalent ionic Page 22 metallic (1) (Total 3 marks)