Additional Science revision questions

Structue, bonding and some electrolysis

December 2012

402 minutes

402 marks

A copy of this paper and the Markscheme can be found on the VLE

Page 1 of 121

Q1.          The diagram shows how the atoms are joined in part of a diamond.

(a)     Draw a ring around the correct answer to complete each sentence.

   joined by strong bonds. (1)

Diamond has a high melting point because

some

a few

all

of the atoms are

(1)

  one

two

four

 

Each atom is joined to

other atoms.

   

(1)

  covalent.

ionic.

metallic.

The bonds are

 

(1)

  hard.

soft.

shiny.

Diamond is used in cutting tools because it is

 

(i)

(ii)

(iii)

(iv)

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(b)     Diamond is made of carbon.

Name a gas produced when carbon reacts with oxygen.

........................................................................................................................ (1)

(Total 5 marks)

   

Q2.          (a)     Ammonia has the formula NH3. It is made from nitrogen and hydrogen.

How many atoms are in an ammonia molecule? .......................................... (1)

(b)     The diagrams show the electron arrangement in nitrogen and hydrogen.

Which diagram below, A, B, C or D, represents an ammonia molecule?

Write your answer in the box.

Diagram   (1)

(c)     Ammonia dissolves in water to form a solution with a pH of 10.

What does this pH value tell you about ammonia solution?

........................................................................................................................ (1)

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(d)     In industry a large amount of ammonia is neutralised by an acid to make ammonium nitrate.

(i)      What type of substance is ammonium nitrate?

Tick ( ) one box.  

 

 

 

(1)

acid  

alkali  

base  

salt  

(ii)     Which acid is added to ammonia to make ammonium nitrate?

Tick ( ) one box.  

 

 

 

(1)

hydrochloric  

citric  

nitric  

sulfuric  

(iii)     Draw a ring around the main use of ammonium nitrate.

       fertiliser                lubricating oil              medicine               plastic (1)

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(e)     Instant cold packs are used to treat sports injuries.

One type of cold pack has a plastic bag containing water. Inside the bag is a smaller bag containing ammonium nitrate.

The outer bag is squeezed so that the inner bag bursts. The ammonium nitrate dissolves in the water. This process is endothermic.

Explain why the bag becomes cold.

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(Total 8 marks)

   

Q3.          Read the information in the box and then answer the questions.  

Sun Creams

Sun creams contain titanium oxide. This compound absorbs harmful radiation.

Traditional sun creams contain normal-sized particles of titanium oxide. Normal-sized particles of titanium oxide are known to be safe to put on the skin.

Many new sun creams contain nano-sized particles of titanium oxide.

Experiments suggest that nano-sized particles might pass through the pores of the skin more easily than normal-sized particles.

Page 5 of 121

(a)     Explain why nano-sized particles might pass more easily through the pores of the skin than normal sized particles.

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........................................................................................................................ (1)

(b)     Using these sun creams is beneficial because they absorb harmful radiation.

Suggest one possible risk of using these sun creams.

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........................................................................................................................ (1)

(Total 2 marks)

   

Q4.          (a)     An atom of aluminium can be represented as shown below.

In this atom of aluminium the number of protons is ............................. and

the number of neutrons is ............................... (2)

(b)     Which statement in the table below describes the mass of an electron?

Tick ( ) one box.  

(1)

Statement Tick ( )

Electrons have a very small mass compared to protons.  

Electrons have about the same mass as protons.  

Electrons are much heavier than protons.  

Electrons have about the same mass as neutrons.  

Page 6 of 121

(c)     Which method is used to extract aluminium from aluminium oxide?

Tick ( ) one box.  

(1) (Total 4 marks)

   

Method Tick ( )

Heating aluminium oxide.  

Heating aluminium oxide with carbon.  

Electrolysis of molten aluminium oxide.  

Heating aluminium oxide with copper.  

Q5.          Read the information in the box and then answer the question.  

Aluminium is made by the electrolysis of aluminium oxide.

Aluminium oxide is an ionic compound containing aluminium ions (Al3+) and oxide ions (O2–).

The diagram below shows the apparatus used to electrolyse aluminium oxide.

Page 7 of 121

(a)     In this question you will get marks on using good English, organising information clearly and using specialist terms correctly.

Use information in the box and your knowledge and understanding of this process to answer this question.

Explain, as fully as you can, how aluminium and carbon dioxide are formed in this process.

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(b)     Aluminium is a metal.

Explain why aluminium conducts electricity.

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(Total 8 marks)

   

Page 8 of 121

Q6.          The following steps show how to use a type of glue.

          Step 1 Measure out equal amounts of the liquids from tubes A and B.

          Step 2 Mix the liquids to make the glue. Put a thin layer of the glue onto each of the surfaces to be joined.

          Step 3 Assemble the pieces to be joined and then hold them together with tape.

Step 4 Leave the glue to set.

(a)     When liquids A and B are mixed a chemical reaction takes place.

(i)      This reaction is exothermic.

         State how the temperature of the mixture will change as the glue is mixed.

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........................................................................................................................... (1)

(ii)     When the glue sets it forms a giant covalent structure.

         Explain why substances with giant covalent structures have high melting points.

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(b)     The time taken for the glue to set at different temperatures is given in the table below.

 

          Explain, in terms of particles, why increasing the temperature changes the rate of the reaction which causes the glue to set.

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(Total 5 marks)

   

Temperature in °C Time taken for the glue to set

20 3 days

60 6 hours

90 1 hour

Page 10 of 121

Q7.          Read the article and then answer the questions.  

Nanotennis!

Tennis balls contain air under pressure, which gives them their bounce. Normal tennis balls are changed at regular intervals during tennis matches because they slowly lose some of the air.

‘Nanocoated’ tennis balls have a ‘nanosize’ layer of butyl rubber. This layer slows down the escape of air so that the ball does not lose its pressure as quickly.

(a)     What is the meaning of nanosize?

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..................................................................................................................................... (1)

(b)     Suggest why using ‘nanocoated’ tennis balls would be good for the environment.

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(Total 3 marks)

 

Page 11 of 121

Q8.          This barbecue burns propane gas.

                                                 

          The structure of propane is shown below.

                                                         

(a)     Complete the diagram to show how the outer energy level (shell) electrons of hydrogen and carbon are arranged in a molecule of propane.

(1)

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(b)     The graph shows how the vapour pressure of propane changes with temperature.

          The vapour pressure of a liquid is the pressure of the vapour above the liquid.

(i)      Describe, as fully as you can, how the vapour pressure of propane changes with temperature.

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(ii)     The boiling point of a liquid is the temperature at which its vapour pressure is equal to the air pressure above the liquid.

         Use the graph to find the boiling point of propane when the air pressure is 100 kilopascals.

Boiling point ................................................... °C (1)

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(c)     Explain, in terms of molecules, why propane has a low boiling point.

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(Total 6 marks)

   

Q9.          This label was on a container of graphite lubricant.

 

Super G Graphite Lubricant

Super G forms a thin anti-friction film on metal surfaces. It provides good lubrication when metal parts rub against each other.

(a)     Give one reason why a lubricant is used when metal parts rub against each other.

.....................................................................................................................................

..................................................................................................................................... (1)

(b)     The diagram shows the arrangement of atoms in graphite.

(i)      Draw a ring around the type of atoms in graphite.

                      aluminium                      carbon                       silicon (1)

Page 14 of 121

(ii)     Graphite is a good lubricant because it is slippery. Use the diagram to explain why graphite is slippery.

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(Total 4 marks)

 

Q10.          This question is about oxygen atoms. The periodic table on the Data Sheet may help you to answer this question.

(a)     (i)      Oxygen atoms have 8 electrons.

         Complete the diagram to represent the arrangement of electrons in an oxygen atom. Use crosses (×) to represent the electrons.

                                            (1)

(ii)     Name the part of the oxygen atom that is labelled A on the diagram.

........................................................................................................................... (1)

(b)     Two isotopes of oxygen are oxygen-16 and oxygen-18.

16                                  18                                  

                                                  

                oxygen-16                     oxygen-18

                                                                      

O O8 8

Page 15 of 121

          Explain, in terms of particles, how the nucleus of an oxygen-18 atom is different from the nucleus of an oxygen-16 atom.

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(Total 4 marks)

 

Q11.         The diagram represents an atom of beryllium.

Use a number from the box to complete each sentence.  

(a)     The atomic number (proton number) of this atom is . (1)

(b)     The mass number of this atom is . (1)

(Total 2 marks)

   

         4            7            9           12

Page 16 of 121

Q12.          This question is about fluorine and some of its compounds.

(a)     The diagram represents a molecule of hydrogen fluoride.

                                                  

          Draw a ring around the type of bonding that holds the hydrogen and fluorine atoms together in this molecule.

                               covalent                      ionic                       metallic (1)

(b)     Fluorine is made in industry by the electrolysis of a mixture of potassium fluoride and hydrogen fluoride.

(i)      Use one word from the box to complete the sentence.  

         To allow electrolysis to take place the mixture of potassium fluoride and

         hydrogen fluoride must be .................................................. . (1)

     gas                          liquid                        solid

(ii)     The mixture of potassium fluoride and hydrogen fluoride contains fluoride ions

(F–), hydrogen ions (H+) and potassium ions (K+).

         Use one word from the box to complete the sentence.  

         During electrolysis the element formed at the positive electrode is

         ............................................................ . (1)

      fluorine                hydrogen         potassium

(c)     Fluoride ions are sometimes added to drinking water. It is thought that these ions help to reduce tooth decay.

(i)      Tick ( ) one question that cannot be answered by scientific investigation alone.  

(1)

Question Tick ( )

Do fluoride ions in drinking water reduce tooth decay?  

Are fluoride ions in drinking water harmful to health?  

Should fluoride ions be added to drinking water?  

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(ii)     Explain why you have chosen this question.

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........................................................................................................................... (1)

(Total 5 marks)

 

Q13.          This drill contains an electric motor.

                                    

          The diagram below shows the main parts of an electric motor.

                                

          The carbon contacts are made of graphite. Springs push the contacts against the copper ring. The carbon contacts conduct electricity to the copper ring. The copper ring rotates rapidly but does not stick or become worn because the graphite is soft and slippery.

(a)     Using this information give two properties that make graphite suitable for making the carbon contacts.

1 ...................................................................................................................................

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2 ...................................................................................................................................

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Page 18 of 121

(b)     (i)      Draw a ring around the correct word in each box to complete the sentence.

         Each carbon atom in graphite is joined to  

(2)

two

three

four

 

other carbon atoms by

covalent

ionic

metallic

 

bonds.

(ii)     Tick ( ) the statement which explains why graphite is soft and slippery.  

(1) (Total 5 marks)

 

Statement Tick ( )

It is made of layers of atoms.  

It is made of small molecules.  

It is an ionic compound.  

Q14.          Read the article and then answer the questions that follow.  

Hydrogen fuel for cars?

Hydrogen is an excellent fuel. On combustion it reacts with oxygen from the air to release a large amount of energy. The only product of combustion is water which does not cause pollution. Hydrogen gas can be stored under pressure in a cylinder but a leak of the gas could cause an explosion.

It has been found that lithium nitride can absorb and then release large volumes of hydrogen. Hydrogen stored in lithium nitride will not explode.

The problem is that the rate at which hydrogen is absorbed and then released from normal sized particles of lithium nitride is slow.

Recently scientists have made ‘nanosized’ particles of lithium nitride. The ‘nanosized’ particles have the advantage that they absorb and release the hydrogen much faster when needed in the fuel cell.

Page 19 of 121

(a)     Use information from the article to help you to answer these questions.

(i)      Give two reasons why hydrogen is an excellent fuel.

1 .........................................................................................................................

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2 .........................................................................................................................

........................................................................................................................... (2)

(ii)     Hydrogen stored in lithium nitride is safer in an accident than a cylinder full of hydrogen gas.

         State why.

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........................................................................................................................... (1)

(iii)     What is the advantage of using ‘nanosized’ particles of lithium nitride instead of normal sized particles for storing hydrogen?

...........................................................................................................................

........................................................................................................................... (1)

(b)     Lithium nitride is an ionic compound that contains lithium ions (Li+) and nitride ions

(N3–).

(i)      The periodic table on the Data Sheet may help you to answer this question.

         Which diagram, A, B or C, represents the electronic structure of a lithium atom? Write your answer in the box.

Diagram (1)

Page 20 of 121

(ii)     Tick ( ) the statement which describes how a lithium atom (Li) changes into a lithium ion (Li+).

 

(1)

Statement Tick ( )

A lithium atom loses a neutron.  

A lithium atom loses an electron.  

A lithium atom loses a proton.  

(iii)     The diagram shows the electronic structure of a nitrogen atom.

                                                

         Which diagram, A, B or C, represents the electronic structure of a nitride ion (N3–)?

Write your answer in the box.

                

Diagram (1)

(c)     The equation for the reaction of lithium nitride with hydrogen is:

                                                Li3N + 2H

2  LiNH

2 + 2LiH

          What does the symbol  mean?

          Draw a ring around your answer.

             reversible reaction               endothermic reaction              neutralisation (1)

(d)     Draw a ring around the correct answer in each box to complete the sentences.  

         than normal sized particles of lithium nitride. (1)

 

(i)       ‘Nanosized’ particles of lithium nitride will be

much larger

a little larger

much smaller

Page 21 of 121

(ii)     One of the reasons why ‘nanosized’ particles have different properties  

         than normal sized particles of lithium nitride. (1)

(Total 10 marks)

 

 

from normal sized particles is that they have a greater

density

mass

surface area

Q15.          Perfumes contain a mixture of chemicals.

                                                                       

          The main ingredients of perfumes are a solvent and a mixture of fragrances.

(a)     A sample of the solvent used in one perfume contained 0.60 g of carbon, 0.15 g of hydrogen and 0.40 g of oxygen.

          Relative atomic masses: H = l; C = 12; O = 16.

          Calculate the empirical (simplest) formula of the solvent.

          You must show all of your working to gain full marks for this question.

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(b)     Solvent molecules evaporate easily.

          Explain why substances made of simple molecules evaporate easily.

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(c)     Most companies claim that their perfumes have been tested on skin. A study was made of the tests they used. The study found that each company used different tests.

          The perfumes were tested in the companies’ own laboratories and not by independent scientists.

          Some companies did not give any information about the tests that they had used.

(i)      Suggest why companies test their perfumes on skin.

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(ii)     Did the study show that the tests made by the different companies were valid and reliable?

         Explain your answer.

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(Total 9 marks)

 

Page 23 of 121

Q16.          The diagram represents a particle of methane.

(a)     What is the formula of methane? ............................................................................... (1)

(b)     Choose a word from the box to answer the question.

 

Which of the words best describes the methane particle shown in the diagram?

................................................. (1)

atom                   ion                   molecule

(c)     Choose a word from the box to answer the question.

 

What is the type of bonding shown in the diagram?

.................................................. (1)

(Total 3 marks)

 

covalent             ionic                 metallic

Page 24 of 121

Q17.          This question is about giant structures. Diamond, graphite and silicon dioxide all have giant structures.

(a)     The diagrams show the structures of these three substances.

Draw a line from each structure to its name.

(2)

(b)     Complete the sentences using words from the box.

 

(i)      Diamond, graphite and silicon dioxide have high melting points because all the

atoms in their structures are joined by strong ............................................... bonds. (1)

(ii)     In diamond each atom is joined to ............................................... other atoms. (1)

       covalent                   four                  hard                 ionic

          shiny                      soft                  three                 two

(iii)     Diamond can be used to make cutting tools because it has a rigid structure which

makes it very ................................................ (1)

(iv)    In graphite each atom is joined to ............................................... other atoms. (1)

(v)     Graphite can be used to make pencils because it has a structure which makes it

................................................ (1)

Page 25 of 121

(c)     When a diamond is heated to a high temperature and then placed in pure oxygen it burns. Carbon dioxide is the only product.

Name the element in diamond. ................................................................................... (1)

(Total 8 marks)

 

Q18.          Read this passage about metals.

 

(a)     State why metals can be bent and hammered into different shapes.

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Metals are crystalline materials. The metal crystals are normally about 20 000 nm (nanometres) in diameter. The atoms inside these crystals are arranged in layers.

A new nanoscience process produces nanocrystalline metals. Nanocrystalline metals are stronger and harder than normal metals.

It is hoped that nanocrystalline metals can be used in hip replacements.

The use of nanocrystalline metals should give people better hip replacements which last longer.

Page 26 of 121

(b)     How is the size of the crystals in nanocrystalline metals different from the size of the crystals in normal metals?

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(c)     Hip joints are constantly moving when people walk.

          Suggest and explain why the hip replacement made of nanocrystalline metal should last longer than one made of normal metals.

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(Total 4 marks)

 

Q19.          The electrolysis of sodium chloride solution produces useful substances.

(a)     Explain the meaning of electrolysis.

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Page 27 of 121

(b)     The diagram shows an apparatus used for the electrolysis of sodium chloride solution.

Reproduced with the permission of Nelson Thornes Ltd from PATRICK FULLICK et al, ISBN 0-7487-9644- 4. First published in 2006

The electrolysis produces two gases, chlorine and Gas A.

Name Gas A ............................................................................................................... (1)

(c)     The electrodes used in this process can be made of graphite. Explain why graphite conducts electricity.

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(Total 5 marks)

 

Q20.          (a)     Write a balanced symbol equation for the reaction between magnesium (Mg) and oxygen (O

2) to form magnesium oxide (MgO).

..................................................................................................................................... (1)

Page 28 of 121

(b)     The diagram shows the electronic structure of a magnesium atom. The atomic (proton) number of magnesium is 12.

                 Magnesium atom

Draw a similar diagram to show the electronic structure of an oxygen atom. The atomic (proton) number of oxygen is 8.

(1)

(c)     Magnesium ions and oxide ions are formed when magnesium reacts with oxygen.

The diagram shows the electronic structure of an oxide ion.

                       Oxide ion

Draw a similar diagram to show the electronic structure of a magnesium ion.

 

 

 

 

 

  (1)

(d)     Magnesium oxide is a white solid with a high melting point.

Explain how the ions are held together in solid magnesium oxide.

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(e)     Indigestion tablets can be made from magnesium oxide. The magnesium oxide neutralises some of the hydrochloric acid in the stomach.

          Complete the word equation for the reaction between magnesium oxide and hydrochloric acid.

hydrochloric acid  +  magnesium oxide  →  ......................  +  water. (1)

(Total 6 marks)

 

Q21.          Bricks made from silica (silicon dioxide) are used to line furnaces that operate at high temperatures.

Part of the structure of silica is shown in the diagram.

Page 30 of 121

          Use words from the box to complete the sentences.

 

          One reason for using silica to make bricks for high-temperature furnaces is that silica has a

.......................................... melting point.

Silica has this property because it is a .......................................... structure in which each silicon

atom is joined to .......................................... oxygen atoms by ..........................................

bonds. (Total 4 marks)

 

covalent           giant           low           small

 

            four           high           six           weak

Q22.          (a)     The diagram represents an atom of nitrogen.

(i)      Use words from the box to label the diagram.

 

(2)

electron          neutron          nucleus          proton

(ii)     Draw a ring around the mass number of this atom.

          5           7             14           21 (1)

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(b)     Nitrogen can react with hydrogen to make ammonia, NH3 .

          Which diagram, A, B, C or D, best represents an ammonia molecule?           (1)

(Total 4 marks)

 

Q23.          Aluminium is a useful metal.

(a)     The atomic number (proton number) of aluminium is 13.

          Complete the diagram to show the electronic structure of an aluminium atom. Use crosses (x) to represent the electrons.

(1)

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(b)     Aluminium is used as the electrical conductor for overhead power cables.

          Explain why metals are good conductors of electricity.

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(Total 3 marks)

 

Q24.          Hydrogen chloride (HCl) can be made by the reaction of hydrogen (H2) with chlorine (Cl

2).

(a)     The diagrams represent molecules of hydrogen and chlorine.

          Draw a similar diagram to represent a molecule of hydrogen chloride (HCl). You need show only the outer energy level (shell) electrons.

 

 

 

 

 

  (1)

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(b)     The word equation for the reaction of hydrogen with chlorine is shown below.

hydrogen  +  chlorine  →  hydrogen chloride

          Write a balanced symbol equation for this reaction.

..................................................................................................................................... (2)

(c)     Hydrogen chloride gas reacts with magnesium to form the ionic compound called magnesium chloride. Use the table of ions on the Data Sheet to help you to write the formula of magnesium chloride.

..................................................................................................................................... (1)

(d)     Why does magnesium chloride have a much higher melting point than hydrogen chloride?

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(Total 6 marks)

   

Q25.          The drawing shows a high quality wire used to make electrical connections on a hi-fi system.

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(a)     Copper is used because it is a very good conductor of electricity. Copper is a typical metal.

(i)      Describe the structure and bonding in a metal. You may wish to draw a diagram to help you to answer this question.

         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.

 

 

 

 

 

 

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(ii)     Explain, by reference to your answer to part (a)(i), why copper conducts electricity.

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(iii)     Explain, by reference to your answer to part (a)(i), why copper can be drawn into wires.

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(b)     The copper used to make this wire is “OFC” copper. This stands for ‘oxygen free copper’.

(i)      It is thought that when molten copper is cooled and solidified it can take in some oxygen from the air. This may slightly decrease the conductivity of the copper.

Suggest why the conductivity might be decreased.

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(ii)     To make it oxygen free, the copper is heated in an atmosphere of hydrogen.

         Explain how this will remove the oxygen.

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(Total 8 marks)

 

Q26.          (a)     A tin of red kidney beans contains calcium chloride as a firming agent.

          Calcium chloride is an ionic compound which contains calcium ions (Ca2+) and chloride

ions (Cl–).

(i)      The diagram on the left represents the electronic structure of a chlorine atom.

         Complete a similar diagram on the right to represent a chloride ion.

(2)

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(ii)     Explain how a calcium atom changes into a calcium ion which has a 2+ charge.

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(b)     Cola drinks contain phosphoric acid, H3PO

4. The two equations show how phosphoric acid

can be made from phosphorus.

          Balance these two equations.

(i)      P4 + ........ O

2 → P

4O

10

(1)

(ii)     P4O

10 + ................ H

2O → 4H

3PO

4

(1) (Total 6 marks)

 

Q27.          Silicon is an important element used in the electronics industry.

(a)     Silicon can be made by heating a mixture of sand (silicon dioxide) with magnesium powder.

          The equation for this reaction is shown below.

SiO2 (s)+ 2Mg (s) → 2MgO (s) + Si (s)

          Calculate the mass of silicon dioxide needed to make 1 g of silicon.

          Relative atomic masses: O = 16; Si = 28

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Mass = ........................................................g (3)

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(b)     The resulting mixture of magnesium oxide and silicon is added to a beaker containing hydrochloric acid. The silicon is then filtered from the solution.

(i)      The magnesium oxide reacts with the hydrochloric acid and forms magnesium chloride (MgCl

2) solution and water.

 magnesium oxide + hydrochloric acid → magnesium chloride solution + water

         Write a balanced symbol equation for this reaction, including state symbols.

.......................................................................................................................... (2)

(ii)     The gases produced are a mixture of several silicon hydrides.

         One of the gases produced in the reaction is the silicon hydride with the formula SiH4.

The structure of this molecule is similar to methane, CH4.

         Draw a diagram to show the bonding in a molecule of SiH4. Represent the electrons

as dots and crosses and only show the outer shell (energy level) electrons.

 

 

 

 

 

 

  (1)

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(iii)     A sample of a different silicon hydride was found to contain 1.4 g of silicon and 0.15 g of hydrogen.

         Calculate the formula of this silicon hydride. You must show all your working to gain full marks.

         Relative atomic masses: H = 1; Si = 28

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........................................................................................................................... (4)

(iv)    The silicon hydrides react immediately they come into contact with oxygen in the air. They burst into flames with a small explosion and give out energy.

         Which letter, A to H, best describes this reaction?

 

Letter ................... (1)

Energy involved in breaking and forming bonds

Activation energy

Rate of reaction

Letter

    fast A The energy released from forming new bonds is greater than the energy needed

high slow B

to break existing bonds   fast C

  low slow D

    fast E The energy needed to break existing bonds is greater than the energy released from

high slow F

forming new bonds low fast G

    slow H

Page 39 of 121

(c)     The structure of silicon is similar to the structure of diamond.

          Describe the structure of silicon and explain why it has a high melting point. You may draw a diagram if this helps.

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..................................................................................................................................... (4)

(Total 15 marks)

 

Q28.          Millions of years ago the Earth formed as a giant ball of molten rock. The outer surface cooled forming a thin, solid outer crust. Volcanic activity on the surface produced an atmosphere containing the compounds carbon dioxide, ammonia, methane and water vapour.

          Describe the bonding in any one of these compounds. You must include electronic structures in your explanation.

...............................................................................................................................................

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............................................................................................................................................... (Total 4 marks)

 

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Q29.          There is molten rock below the Earth’s solid outer crust. The rock remains molten because the radioactive decay of isotopes such as uranium, thorium and potassium releases heat energy.

(i)      Explain how this released heat energy is thought to cause the recycling of rocks.

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..................................................................................................................................... (4)

(ii)      Two isotopes of potassium are shown.

                                

          Explain what is meant by isotopes. You must include numbers of electrons, neutrons and protons in your explanation.

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(Total 8 marks)

 

Page 41 of 121

Q30.          Uranium metal can be produced by reacting uranium hexafluoride with calcium.

UF6  +  3Ca  →  3CaF

2  +  U

(a)     Describe how calcium and fluorine bond together to form calcium fluoride. The electron arrangement of each atom is shown.

.....................................................................................................................................

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..................................................................................................................................... (5)

(b)     Uranium has two main isotopes, and . Use these as examples to explain what is meant by the word isotope.

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..................................................................................................................................... (4)

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(c)     At the start of a reaction there was 174.5 g of uranium hexafluoride, UF6.

Relative atomic masses: F 19; U 235

(i)      Calculate the relative formula mass of uranium hexafluoride, UF6.

         ...........................................................................................................................

         ...........................................................................................................................

         ...........................................................................................................................

Relative formula mass UF6 = .................................... g

(1)

(ii)     Calculate the mass of uranium that would be produced from 134.5 g of uranium hexafluoride.

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................

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...........................................................................................................................

Mass of uranium = .................................. g (2)

(Total 12 marks)

   

Q31.         The diagrams show three isotopes of potassium.

Page 43 of 121

(i)      In what way does the atomic structure show you that they are all atoms?

.....................................................................................................................................

..................................................................................................................................... (1)

(ii)      Explain why these three atoms are called isotopes of potassium.

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..................................................................................................................................... (3)

(Total 4 marks)

   

Q32.          Many everyday substances can be classified as acids, bases or salts. For example, car batteries contain sulphuric acid, oven cleaners contain sodium hydroxide and table salt contains sodium chloride.

(a)           A solution of each of these substances was tested with universal indicator.

 

Solution Colour of universal indicator

Sulphuric acid (H2SO

4) red

Sodium hydroxide (NaOH) purple

Sodium chloride (NaCl) green

(i)      Explain how these universal indicator colours and the corresponding pH values could be used to identify each of these solutions.

...........................................................................................................................

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........................................................................................................................... (3)

Page 44 of 121

(ii)     Name and give the formula of the ion which causes the solution to be acidic.

Name of ion ..................................................................................................

Formula of ion ................................................................................................. (2)

(b)     Sodium chloride can be made by reacting sodium hydroxide with hydrochloric acid in the presence of an indicator.

(i)      What is the name of this type of reaction?

.......................................................................................................................... (1)

(ii)     Write a balanced chemical equation for this reaction.

..............(aq)  +  ..............(aq)  →  ..............(aq)  +  ..............(l) (2)

(c)     The atomic number for sodium is 11 and for chlorine is 17.

(i)      Complete the diagrams to show the electron arrangements for a sodium atom and a chlorine atom.

(2)

(ii)     These atoms form different particles by one electron transferring from the sodium atom to the chlorine atom. What is the name given to the particles formed?

........................................................................................................................... (1)

(iii)     Why do these sodium and chloride particles bond?

...........................................................................................................................

........................................................................................................................... (1)

Page 45 of 121

(d)     Sodium chloride solution is electrolysed to form three products, hydrogen, chlorine and sodium hydroxide.

Describe how each of these products are formed.

.....................................................................................................................................

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..................................................................................................................................... (3)

(Total 15 marks)

 

Q33.          Brine, a solution containing sodium chloride in water, can be used to manufacture chlorine, hydrogen and sodium hydroxide. A student sets up a simplified model of the industrial cell.

          (a)     The electron arrangements of some atoms are shown here.

          H         1

          O         2.6

          Na       2.8.1

          C1        2.8.7

Page 46 of 121

(i)      Use the relevant electron arrangements to describe the bonding in water.

...........................................................................................................................

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........................................................................................................................... (2)

(ii)     Use the relevant electron arrangements to describe the bonding in sodium chloride.

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........................................................................................................................... (3)

(b)     Use the atomic structures of  and  to explain the meaning of the term isotopes.

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..................................................................................................................................... (3)

(Total 8 marks)

 

Page 47 of 121

Q34.          Many everyday substances can be classified as acids, bases or salts. For example, car batteries contain sulphuric acid, oven cleaners contain sodium hydroxide and table salt contains sodium chloride.

(a)           A solution of each of these substances was tested with universal indicator.

 

Solution Colour of universal indicator

Sulphuric acid (H2SO

4) red

Sodium hydroxide (NaOH) purple

Sodium chloride (NaCl) green

(i)      Explain how these universal indicator colours and the corresponding pH values could be used to identify each of these solutions.

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................

........................................................................................................................... (3)

(ii)     Name and give the formula of the ion which causes the solution to be acidic.

Name of ion ..................................................................................................

Formula of ion ................................................................................................. (2)

(b)     Sodium chloride can be made by reacting sodium hydroxide with hydrochloric acid in the presence of an indicator.

(i)      What is the name of this type of reaction?

.......................................................................................................................... (1)

(ii)     Write a balanced chemical equation for this reaction.

..............(aq)  +  ..............(aq)  →  ..............(aq)  +  ..............(l) (2)

Page 48 of 121

(c)     The atomic number for sodium is 11 and for chlorine is 17.

(i)      Complete the diagrams to show the electron arrangements for a sodium atom and a chlorine atom.

(2)

(ii)     These atoms form different particles by one electron transferring from the sodium atom to the chlorine atom. What is the name given to the particles formed?

........................................................................................................................... (1)

(iii)     Why do these sodium and chloride particles bond?

...........................................................................................................................

........................................................................................................................... (1)

(d)     Sodium chloride solution is electrolysed to form three products, hydrogen, chlorine and sodium hydroxide.

Page 49 of 121

Describe how each of these products are formed.

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..................................................................................................................................... (3)

(Total 15 marks)

 

Q35.          Fluorine is a very useful element. It is placed in group 7 of the Periodic Table.

          Use your knowledge of the elements in group 7 to help you answer these questions. You may find that information in the Data Sheet may help you with this question.

(a)     Name another element in group 7 of the Periodic Table.

..................................................................................................................................... (1)

(b)     Cylinders filled with fluorine molecules are commercially available. What would you expect the formula of a fluorine molecule to be?

..................................................................................................................................... (1)

(c)     Fluoride ions are added to drinking water to help prevent tooth decay. What is the charge on fluoride ions in the water?

..................................................................................................................................... (1)

(d)     Fluorine reacts with the non-metal sulphur to make sulphur hexafluoride (SF6).

(i)      What type of bonding would you expect in sulphur hexafluoride?

.......................................................................................................................... (1)

(ii)     Explain the reason for your answer to part (i).

..........................................................................................................................

..........................................................................................................................

.......................................................................................................................... (1)

(Total 5 marks)

 

Page 50 of 121

Q36.          Silicon is an extremely important element. More than a million tonnes of silicon are produced each year. Silicon is made by reducing silicon oxide (sand) with carbon (coke).

(a)     (i)      Complete the diagram below to show the arrangement of electrons in an atom of silicon. The Data Sheet may help you with this question.

(2)

(ii)     Which electrons in the silicon atom take part in chemical reactions with other atoms?

..........................................................................................................................

.......................................................................................................................... (1)

(iii)     What features of all the atoms of the elements in group 4 of the Periodic Table might give them similar chemical properties?

..........................................................................................................................

.......................................................................................................................... (1)

(b)     Silicon is difficult to classify as a metal or a non-metal because it has properties which resemble both. Some of the properties of silicon are listed below.

•        Silicon is a shiny blue/grey solid. •        Silicon is placed in Group 4 of the Periodic Table. •        Silicon has a relative atomic mass of 28. •        Silicon has a very high melting point (1410ºC). •        Silicon has a very high boiling point (2355ºC). •        Silicon conducts electricity. •        Silicon oxide will neutralise alkalis. •        Silicon forms compounds in which the silicon atoms are bonded to other atoms by

covalent bonds.

(i)      Select two properties from the list above in which silicon resembles a metal.

1. .....................................................................................................................

2. ..................................................................................................................... (2)

Page 51 of 121

(ii)     Select two properties from the list above in which silicon resembles a non-metal.

1. .....................................................................................................................

2. ..................................................................................................................... (2)

(Total 8 marks)

 

Q37.          The hydrogen halides (hydrogen fluoride, hydrogen chloride, hydrogen bromide and hydrogen iodide) are important chemicals.

          The diagram below represents a molecule of hydrogen chloride.

(i)      What type of particles are represented by the crosses (X)?

..................................................................................................................................... (1)

(ii)      What type of chemical bond holds the atoms in this molecule together?

.....................................................................................................................................  (1)

(iii)     Would you expect hydrogen chloride to be a gas, a liquid or a solid, at room temperature and pressure? Explain your answer.

.....................................................................................................................................

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..................................................................................................................................... (3)

(Total 5 marks)

   

Page 52 of 121

Q38.          The extract below was taken from a leaflet on the uses of platinum. One of the uses described was in making electrodes for spark plugs in car engines. The spark plug produces the spark which ignites the fuel in the engine.

 

Spark Plugs

The electrodes in a spark plug have to conduct electricity very well. Since they project into the combustion chamber of the engine, they must also be able to withstand extremely high temperatures in a very corrosive atmosphere.

Nickel-based plugs have been produced for many years. They only last a fairly short time. As the electrodes wear, combustion becomes less efficient and the petrol is not burnt completely.

Platinum and other precious metals can now be used in spark plugs. These last much longer and are more efficient. This can help to reduce air pollution.

          The table below gives some information about platinum and nickel.  

  MELTING

POINT (° C)

BOILING POINT (° C)

POSITION IN REACTIVITY

SERIES

COST (£/kg)

nickel 1455 2920 Higher than gold 2.5

platinum 1769 4107 below gold 6110

(a)     Compare nickel and platinum for use in making the electrodes in spark plugs.

          A good answer should give advantages and disadvantages of each metal linking these to the properties of the metals. Marks will be given for the way in which you organise your answer.

          You will need a sheet of lined paper. (8)

(b)     (i)      Describe the structure and bonding in metals.

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(ii)     Explain why metals such as nickel and platinum are good conductors of electricity.

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........................................................................................................................... (2)

(Total 13 marks)

 

Q39.          (a)     The electronic structure of a sodium atom can be written 2,8,1. Write the electronic structure of a potassium atom in the same way.

..................................................................................................................................... (1)

(b)     The electronic structure of a sodium atom can also be represented as in the diagram below.

(i)      Draw a similar diagram for a fluorine atom.

 

 

 

 

 

(ii)     Draw similar diagrams to show the electronic structure of the particles in sodium fluoride.

 

 

 

 

  (4)

(Total 5 marks)

 

Page 54 of 121

Q40.          Diesel oil is obtained from crude oil. It can be used as a fuel for car engines. The diagram below represents a compound found in diesel oil.

(a)     What is the formula of this compound?

..................................................................................................................................... (1)

(b)     Each of the lines on the diagram above represents a covalent bond.

What is a covalent bond?

.....................................................................................................................................

..................................................................................................................................... (2)

(Total 3 marks)

 

##

          Sando-K is a medicine. It is given to people whose bodies contain too little of a particular element.

          Sando-K is a mixture of two compounds. The formulae of the two compounds are given below.

KHCO                 KC1

(a)     Which metal do people given Sando-K need?

..................................................................................................................................... (1)

(b)     Sando-K contains the ion, CO . Which gas would be produced if a dilute acid was added to Sando-K? (The Data Sheet may help you to answer this question.)

..................................................................................................................................... (1)

(c)     The compounds in Sando-K contain ions.

Complete the two sentences below.

Atoms change into positive ions by ....................................... one or more

............................................................. .

Atoms change into negative ions by ......................................... one or

more .................................................... . (4)

3

32–

Page 55 of 121

(d)     Electricity can be used to show that an aqueous solution of Sando-K contains ions.

(i)      Draw a diagram of an apparatus that you could use to prove that Sando-K contains ions.

 

 

 

 

  (4)

(ii)     Explain, as fully as you can, what would happen when the electricity is switched on.

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(Total 13 marks)

 

Q42.          Calcium and magnesium are elements. They are found in the Earth’s crust as compounds, often carbonates and sulphates. Magnesium is also found as its chloride.

(a)     Calcium and magnesium are in the same Group in the Periodic Table. State which Group this is.

..................................................................................................................................... (1)

(b)     Use the Data Sheet to help you to answer this question.

(i)      Write the chemical formula of magnesium chloride.

........................................................................................................................... (1)

(ii)     Name the type of bonding in magnesium chloride.

........................................................................................................................... (1)

(Total 3 marks)

 

Page 56 of 121

Q43.          Sulphur hexafluoride is a colourless, odourless, non-flammable gas, which is insoluble in water and extremely unreactive.  It is used as an insulator in high voltage transformers and switchgear.

The diagram below represents a molecule of sulphur hexafluoride.

(a)     What type of chemical bond holds the sulphur and fluorine atoms together in sulphur hexafluoride molecules?

..................................................................................................................................... (1)

(b)     Explain why sulphur hexafluoride has a low boiling point.

.....................................................................................................................................

..................................................................................................................................... (2)

(c)     Explain how three of the properties of sulphur hexafluoride make it suitable for use as an insulator inside electrical transformers.

Property 1: ..................................................................................................................

Explanation: ...............................................................................................................

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Property 2: ..................................................................................................................

Explanation: ...............................................................................................................

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Property 3: ..................................................................................................................

Explanation: ...............................................................................................................

..................................................................................................................................... (3)

(Total 6 marks)

 

Page 57 of 121

Q44.          Iron is used (as steel) to make the body panels for cars.

          The iron panels have to be bendable so that they can be pressed into the shape required, but must also be strong. The panels must also be able to conduct electricity because they form part of the electrical circuits of the car.

(a)     Iron is a typical metal. Describe the structure and bonding in a metal such as iron. You may use a diagram if you wish.

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..................................................................................................................................... (4)

(b)     Explain how the structure and bonding of iron:

(i)      allows the body panels to conduct electricity;

........................................................................................................................... (2)

(ii)     allows the body panels to be bent into shape;

........................................................................................................................... (1)

(iii)     gives the body panels strength.

........................................................................................................................... (1)

(Total 8 marks)

 

Page 58 of 121

Q45.          The diagram represents the structure of graphite.

          Use your knowledge and understanding of the structure of graphite to explain why graphite can be used:

(a)     in the ‘leads’ of pencils;

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(b)     as an electrical conductor.

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Page 59 of 121

Q46.          The diagram shows a model of part of the giant lattice of a metal.

(a)     Name particles X and Y.

X .....................................................

Y ..................................................... (2)

(b)     Explain, in terms of the giant structure above, why is it possible to bend a piece of metal.

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..................................................................................................................................... (2)

(Total 4 marks)

 

Page 60 of 121

Q47.          Electrons, neutrons and protons are sub-atomic particles.

(a)           Complete the six spaces in the following table.

 

(3)

Name of sub-atomic particle

Relative mass Relative charge

....................................... 1 ........................................

....................................... ........................................ 0

.......................................

.........................................

(b)     An aluminium atom has 13 electrons. How are these arranged in shells around the nucleus?

.................................................................................................................................... (1)

(c)     Chromium atoms have 24 protons and 28 neutrons.

(i)      How many electrons does each neutral chromium atom have?

........................................................................................................................... (1)

(ii)     What is the mass number of chromium?

........................................................................................................................... (1)

(d)     What change occurs to an atom which undergoes the process of reduction in a chemical reaction?

....................................................................................................................................

.................................................................................................................................... (1)

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(e)     The diagram shows part of the ionic lattice of a sodium chloride crystal.

          Explain why the ions in this lattice stay in place.

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.................................................................................................................................... (3)

(Total 10 marks)

 

Q48.          The drawing shows a container of a compound called magnesium chloride.

(i)      How many elements are joined together to form magnesium chloride?

.................................................................................................................................... (1)

(ii)      Magnesium chloride is an ionic compound. What are the names of its ions?

................................................. ions and ................................................. ions (1)

Page 62 of 121

(iii)     How many negative ions are there in the formula for magnesium chloride?

.................................................................................................................................... (1)

(iv)     Complete the sentence.

          Ions are atoms, or groups of atoms, which have lost or gained

......................................... . (1)

(v)     Suggest three properties which magnesium chloride has because it is an ionic compound.

Property 1 ...................................................................................................................

....................................................................................................................................

Property 2 ..................................................................................................................

....................................................................................................................................

Property 3 ..................................................................................................................

.................................................................................................................................... (3)

(Total 7 marks)

 

Q49.          (a)     The diagram shows part of the ionic lattice of a sodium chloride crystal.

(i)      Complete the spaces in the table to give information about both of the ions in this lattice.

 

(2)

Name of ion Charge

..................................................... .....................................................

..................................................... .....................................................

Page 63 of 121

(ii)     When it is solid, sodium chloride will not conduct electricity. However, molten sodium chloride will conduct electricity. Explain this difference.

..........................................................................................................................

..........................................................................................................................

..........................................................................................................................

.......................................................................................................................... (2)

(iii)     Complete the sentence.

         Sodium chloride conducts electricity when it is molten and when it is

.......................................................................................................................... (1)

(b)     The symbol for a calcium atom can be shown like this:

(i)      What is the mass number of this atom?

.......................................................................................................................... (1)

(ii)     What information is given by the mass number?

..........................................................................................................................

.......................................................................................................................... (1)

(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)  +  O2(g)  →  CaO(s)

(1)

Page 64 of 121

(ii)     Describe, in terms of electrons, what happens to a calcium atom when it becomes a calcium ion.

..........................................................................................................................

..........................................................................................................................

..........................................................................................................................

.......................................................................................................................... (2)

(Total 10 marks)

 

Q50.          Ammonium nitrate and ammonium sulphate are used as fertilisers.

(i)      Which acid reacts with ammonia to form ammonium nitrate?

.................................................................................................................................... (1)

(ii)      Which acid reacts with ammonia to form ammonium sulphate?

.................................................................................................................................... (1)

(iii)     The reactions in (i) and (ii) are both exothermic. How can you tell that a reaction is exothermic?

....................................................................................................................................

.................................................................................................................................... (1)

Page 65 of 121

(iv)     The reactions in (i) and (ii) are both examples of acid + base reactions. What is the name of the chemical change which takes place in every acid + base reaction?

.................................................................................................................................... (1)

(Total 4 marks)

 

Q51.          Magnesium oxide is a compound, made up of magnesium ions and oxide ions.

(a)     What is the charge on each magnesium ion? ............................................................. (1)

(b)     Explain how the magnesium ions get this charge.

.....................................................................................................................................

.....................................................................................................................................

..................................................................................................................................... (2)

(Total 3 marks)

 

Q52.         The two carbon atoms represented below are isotopes.

ISOTOPE 1                                       ISOTOPE 2

14  mass number   12 C                                                    C

 6  proton number  6

(a)     Describe two ways in which the isotopes are similar.

.....................................................................................................................................

..................................................................................................................................... (2)

Page 66 of 121

(b)     Describe as fully as you can one way in which they are different.

.....................................................................................................................................

.....................................................................................................................................

..................................................................................................................................... (2)

(Total 4 marks)

   

Q53.          (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.)

.....................................................................................................................................

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.....................................................................................................................................

 

 

 

 

 

 

 

  (5)

Page 67 of 121

(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.

.....................................................................................................................................

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.....................................................................................................................................

.....................................................................................................................................

..................................................................................................................................... (4)

(Total 9 marks)

 

Q54.          The questions which follow refer to the element hydrogen.

(a)     Draw a diagram to show the bonding in one molecule of hydrogen.

 

 

 

 

 

  (2)

Page 68 of 121

(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)

   

Q55.         You will find it helpful to use the information on the Data Sheet when answering this question.

In the nucleus of an aluminium atom are:

          13 protons and    14 neutrons.

(a)     Complete these sentences.

(i)      The mass number of the aluminium atom is ...................................... .

(ii)     In an atom of aluminium there are ....................................... electrons. (2)

Page 69 of 121

(b)     Why is an aluminium atom electrically neutral?

.....................................................................................................................................

.....................................................................................................................................

..................................................................................................................................... (2)

(c)     Complete the table for the element fluorine.  

(3) (Total 7 marks)

   

PARTICLE NUMBER OF PROTONS

NUMBER OF NEUTRONS

NUMBER OF ELECTRONS

Fluorine atom 9   9

Fluoride atom   10  

##

          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.  

(3)

  CALCIUM PHOSPHOROUS FLUORINE

Number of protons in the nucleus 20   9

Number of neutrons in the nucleus 20 16  

Number of electrons   15 9

(b)     Calcium and fluorine atoms can combine to form the compound calcium fluoride, CaF2.

The fluoride ion is represented by F–.

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(i)      Explain how the fluorine atom forms a fluoride ion.

..........................................................................................................................

.......................................................................................................................... (2)

(ii)     How is the calcium ion represented?

.......................................................................................................................... (2)

(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)

(d)     (i)      Sodium chloride, an ionic compound, has a high melting point whereas paraffin wax, a molecular compound, melts easily.

Explain why.

..........................................................................................................................

..........................................................................................................................

..........................................................................................................................

.......................................................................................................................... (2)

(ii)     Molten ionic compounds conduct electricity but molecular compounds are non-conductors, even when liquid.

Explain why.

..........................................................................................................................

..........................................................................................................................

.......................................................................................................................... (2)

(Total 14 marks)

 

Q57.          The diagram shows one molecule of the compound ammonia.

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Write down everything that the diagram tells you about each molecule of ammonia.

...............................................................................................................................................

...............................................................................................................................................

...............................................................................................................................................

...............................................................................................................................................

...............................................................................................................................................

............................................................................................................................................... (Total 4 marks)

 

Q58.          The diagrams show the giant structures of sodium chloride and diamond.

          sodium chloride (melting point 801°C)                     diamond (melting point 4800°C)

(a)     The equation shows how sodium choride could be formed.

          Balance the equation.

Na          +          Cl2

 →  Na Cl

(1)

(b)     By reference to the detailed structure of sodium chloride explain fully why:

(i)      sodium chloride has a quite high melting point,

         ...........................................................................................................................

         ...........................................................................................................................

         ...........................................................................................................................

         ........................................................................................................................... (1)

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(ii)     solid sodium chloride melts when it is heated strongly,

         ...........................................................................................................................

         ........................................................................................................................... (2)

(iii)     molten sodium chloride will conduct electricity.

         ...........................................................................................................................

         ........................................................................................................................... (1)

(c)     By reference to the detailed structure of diamond, explain why the melting point of diamond, is higher than that of sodium chloride.

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

..................................................................................................................................... (2)

(Total 7 marks)

 

Q59.         This question is about the structure of atoms.

(a)     Choose words from the list to complete the sentences below.

electrons      ions      neutrons       protons

In an atom, the particles with a negative charge are called .....................................

Particles in the nucleus with no charge are called .....................................................

An atom has no overall charge because is has the same number of electrons and

.................................................................................................................................... (3)

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(b)     Two isotopes of the element carbon are:

 12               14 C    and       C

6                 6

Complete the table of information for these two isotopes.  

(2) (Total 5 marks)

   

  ATOMIC

NUMBER MASS

NUMBER NUMBER OF PROTONS

NUMBER OF NEUTRONS

12 Isotope       C

6 6 12 6

6

12 Isotope       C

6 6   6

 

Q60.          (a)     Write down the symbols for

          lithium ................................................................................

          fluorine ............................................................................... (2)

(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.

(1)

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(c)     A lithium atom can lose one electron to form a lithium ion which can be written (2)+

A fluorine atom can gain one electron to form a fluoride ion.

          Choose from the list the correct way to write the fluoride ion.

(2,6)+       (2,7)+       (2,7)-       (2,8)+       (2,8)–

Answer .......................................... (2)

(Total 5 marks)

 

Q61.          (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.

(i)      How is a molecule of hydrogen formed from two hydrogen atoms? (You may use a diagram as part of your answer)

...........................................................................................................................

...........................................................................................................................

........................................................................................................................... (2)

(ii)     Why does helium exist only as single atoms?

...........................................................................................................................

...........................................................................................................................

........................................................................................................................... (2)

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(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.

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

..................................................................................................................................... (2)

(Total 6 marks)

 

Q62.          (a)     Copper is a metal. Explain how it conducts electricity.

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

..................................................................................................................................... (2)

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(b)     Graphite is a non-metal.

          Use the information to explain why graphite conducts electricity.

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

..................................................................................................................................... (3)

(Total 5 marks)

 

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M1.          (a)     (i)      all 1

(ii)                four 1

(iii)               covalent 1

(iv)              hard 1

(b)     carbon dioxide accept carbon monoxide accept CO

2 or CO

1 [5]

   

M2.          (a)     4 1

(b)          A 1

(c)     it is alkaline accept alkali / basic / base

1

(d)     (i)      salt 1

(ii)     nitric 1

(ii)     fertiliser 1

(e)     because energy 1

is taken in (from the surroundings) second mark must be linked to energy

1 [8]

   

M3.         (a)     because nano-sized particles are smaller than normal sized particles 1

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(b)          may cause harm when they are inside the body 1

[2]

   

M4.         (a)     13 1

14 1

numbers must be in the order shown

(b)          electrons have a very small mass compared to protons 1

(c)          electrolysis of molten aluminium oxide 1

[4]

   

M5.          (a)     Marks awarded for this answer will be determined by the Quality of Written Communication (QWC) as well as the standard of the scientific response.

No relevant content. 0 marks

There is a brief description of the electrolysis of aluminium oxide. Level 1 (1–2 marks)

There is some description of the electrolysis of aluminium oxide. Level 2 (3–4 marks)

There is a clear, balanced and detailed description of the electrolysis of aluminium oxide.

Level 3 (5–6 marks)

examples of the chemistry points made in the response

•        aluminium oxide is melted / made liquid

•        aluminium ions are attracted to the negative electrode

•        at the negative electrode aluminium is formed or aluminium ions gain electrons

•        oxide ions are attracted to the positive electrode

•        oxygen is formed at the positive electrode or oxide ions lose electrons

•        the oxygen reacts with carbon to make carbon dioxide or carbon dioxide formed at positive electrode.

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(b)     there are delocalised electrons / free electrons / electrons which move within the aluminium / metallic structure

1

therefore these electrons are able to carry the current / charge 1

if the candidates use the terms covalent / ionic / molecules / intermolecular incorrectly in the answer this will limit the mark to a maximum of 1.

[8]

   

M6.          (a)     (i)      increase (owtte) or gets hotter

ignore gives out heat / takes in heat 1

(ii)     any two from:

•        bonds are strong accept hard to break

•        a lot of energy needed to break bonds allow heat for energy

•        all atoms are joined by (covalent bonds accept forms lattice

•        a large number of bonds would need to be broken reference to ionic / metallic = 1 mark intermolecular forces /forces between molecules = max 1 mark ignore electrostatic many strong bonds need to be broken = 2 marks accept ‘double bonds’ as equivalent to bonds

2

(b)     any two from:

•        particles have more energy ignore more vibrations

•        particles move faster ignore move more

•        particles collide more often or more collisions

accept answers such as hit / bump

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•        more particles / particle collisions have the activation energy or more of the particles / particle collisions have enough energy to react or collisions are more energetic / harder (owtte) or more of the collisions are successful

if electrons rather than particles stated then max 1 mark there are more collisions and more of the collisions are successful = 2 marks accept more collisions per second / unit of time for 2 marks accept ‘more successful collisions’ for 1 mark

2 [5]

 

M7.          (a)     1-100 nm in size

or

          a few (hundred) atoms in size accept very / really small / tiny or 10–9

accept billionth of a metre or any number that implies very small accept measured in nanometers if answer ‘very small’ ignore incorrect numerical values

1

(b)     any two from:

•        less tennis balls need to be made

•        tennis balls last longer or don’t have to replace as often

•        less materials / resources / fuel used up / saves resources accept saving materials

•        less energy used or making tennis balls uses energy

accept saving energy

•        less pollution caused accept named pollutant accept global warming / greenhouse effect

•        less waste eg fewer tennis balls going to landfill

2 [3]

 

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M8.          (a)    

allow all dots or all crosses or combination or all e / e–

or – or other suitable symbols centre of symbols must be on or inside overlapping areas within reason

1

(b)     (i)      any two from:

•        no change initially or stays constant at the beginning

•        increase

•        slowly at first and then more rapidly accept converse arguments

allow vapour pressure is 0 at any temperature <–100oC for 1 mark

accept positive correlation accept explanation based on kinetic theory eg particles have more kinetic energy allow reasonable attempt at using numbers

2

(ii)     –44 (using graph) accept –43 to –45 1

(c)     •        intermolecular forces / bonds or forces / bonds between molecules 1

•        bonds / forces are weak covalent bonds are weak = 0 marks if they do not gain either of the marks on the left then allow simple covalent / molecular / made of small molecules for 1 mark

1 [6]

 

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M9.          (a)     reduce wear of metal ie don’t get damaged

or other sensible answer

          or

          stop / reduce friction accept stop metal heating up accept move more smoothly ignore make it slippery / rub more smoothly

          or

          prevent seizing accept can move freely

1

(b)     (i)      carbon 1

(ii)     layers (of atoms) 1

         can slide / slip over each other allow slip off

         or

         weak forces of attraction / weak bonds (between layers) allow no bonds accept there are weak forces of attraction for 1 mark even when there is no reference to layers accept atoms slide over each other (for 1 mark) an answer which only states there are weak bonds would gain 0 mark when there is no reference to layers weak covalent bonds = 0 marks

1 [4]

 

M10.          (a)     (i)     

                 or        1

allow any arrangement of electrons on the shells accept o, x, - or e as representing electrons

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(ii)     nucleus accept nucleus (protons plus neutrons) do not accept protons plus neutrons on its own allow nuclei / nucles / neucleus / phonetic spelling do not accept neutron

1

(b)     it has 2 more neutrons or converse

accept ‘it has more neutrons’ or ‘different number of neutrons’ for 1 mark ‘2 more protons / electrons + correct number of neutrons’ = max 1 mark

          or

          O-16 has 8 neutrons (1 mark)(*)

          O-18 has 10 neutrons (1 mark)(*)

(*)if incorrectly calculated but shows more neutrons in 0-18 allow for 1 mark accept it has more particles or it has 2 more particles for 1 mark ignore any reference to charges just 2 more without reference to particles = 0 marks

2 [4]

 

M11.         (a)     4 1

(b)     9 1

[2]

   

M12.          (a)     covalent 1

(b)     (i)      liquid 1

(ii)     fluorine accept F / F

2

do not accept fluoride 1

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(c)     (i)      should fluoride ions be added to drinking water? 1

(ii)     any one from:

•        not enough reliable/valid evidence

•        may be other factors involved

•        it is an opinion / choice / belief / ethics issue

•        it can’t be scientifically investigated allow can’t do an experiment ignore test mark independently of (c) (i)

1 [5]

 

M13.          (a)     any two from:

•        conducts electricity

•        soft

•        slippery

•        high melting point ignore hardwearing / does not stick apply list principle

2

(b)     (i)      three 1

         covalent 1

(ii)     it is made of layers of atoms 1

[5]

 

M14.          (a)     (i)      gives out a large amount of energy 1

         only water produced / product is non polluting (owtte) allow it does not harm the environment

1

(ii)     does not explode / burst into flames owtte ignore will not react

1

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(iii)     hydrogen absorbed and released much faster allow more efficient allow can store a larger amount

1

(b)     (i)      B 1

(ii)     a lithium atom loses an electron 1

(iii)     C 1

(c)     reversible 1

(d)     (i)      much smaller 1

(ii)     surface area 1

[10]

 

M15.          (a)                  C                     H                O

                     0.60                  0.15             0.40 1

                      12                     1                16

                   = 0.05               = 0.15         = 0.025 1

                       2                      6                 1 1

                                           C2H

6O             

1 mark for dividing the correct amount or multiples of correct amount by A

r

1 mark for proportions 1 mark for whole number ratio – accept any multiple 1 mark for correctly written simplest formula correct formula without working gets only 2 marks correct formula gains full marks provided steps 1 and 2 are correct. ecf can be allowed from step 2 to 3 or step 3 to 4 formula can be in any order eg OH

6C

2

1

Page 86 of 121

(b)     intermolecular forces / bonds 1

          are weak (covalent) bonds are weak = 0

          or

          forces between molecules or bonds between molecules (1)

(attractive) forces are weak = 1

          are weak (1) if no marks awarded, allow low boiling point or small M

r for 1 mark

1

(c)     (i)      to check the safety of the perfume (owtte) accept references to possible harmful / dangerous effects of perfume or possible reactions on skin eg to show it does not damage skin / cause cancer etc. allow to see what it smells like on the skin allow so the company do not have to test on animals

1

Page 87 of 121

(ii)     any two from:

         idea from text linked with an explanation

•        the company claim to have tested the product: but we cannot be certain they have or how thorough they are or how accurately reported

•        companies did not disclose how they did their tests: so they could not be checked or so they could not be shown to be reliable / valid or so they could not be repeated

or converse eg companies should disclose how they did their tests so that results can be checked etc.

•        companies may not have repeated their tests: so they may not be reliable

•        companies do their own tests: so they may be biased or so they may not be truthful about their results or so they may not be reliable or converse eg independent tests should be done so as to ensure there is no bias etc.

•        the companies are using different tests: so the results cannot be compared or so results will be different or so results will not be fair / valid / reliable or converse eg companies should do the same tests so that the results will be fair etc.

•        companies would not give false information because of damage to reputation or it might lead to litigation

2 [9]

 

M16.          (a)     CH4

4 should be below halfway up H / tail of 4 below the dotted line 1

(b)     molecule 1

(c)     covalent 1

[3]

 

Page 88 of 121

M17.          (a)    

all three lines correct gains 2 marks one or two correct gains 1 mark if there are more than 3 lines then lose mark for each extra line

2

(b)     (i)      covalent 1

(ii)     four 1

(iii)     hard 1

(iv)    three 1

(v)     soft 1

(c)     carbon accept C

1 [8]

 

M18.          (a)     any one from:

•        they are made of layers do not accept line / rows / lattice

•        atoms / ions / particles / layers (of atoms) can slide over each other 1

(b)     any one from:

•        smaller / tiny or very small

do not allow small alone

•        correct size range 1 to 100 nanometres

•        a few hundred atoms in size if they state smaller and give a size outside range ignore size if it is less than 20,000

1

Page 89 of 121

(c)     harder 1

          plus one from:

•        so does not wear as quickly / erode as quickly ignore corrode

•        less vulnerable to damage owtte harder to wear down = 1 mark

•        because they have a high surface area to volume ratio

          or

          stronger (1)

          plus one from: (1)

•        less likely to break / do not break accept withstand pressure

•        not as vulnerable to damage owtte harder and stronger alone gains 1 mark

•        do not bend out of shape

•        because they have a high surface area to volume ratio 1

[4]

 

M19.          (a)     electric current / electricity 1

          plus one from:

•        is passed through ionic compound / substance / electrolyte

•        passed through molten/aqueous compound / substance must be linked to electricity allow liquid compound / substance do not allow solution / liquid alone

•        causing decomposition accept split up / breakdown / breaking up owtte ignore separated accept elements are formed ignore new substances form

1

(b)     hydrogen accept H

2

do not accept H / H2

1

Page 90 of 121

(c)     one electron from each atom accept each carbon is bonded to three other carbon atoms leaving one (unbonded) electron owtte

1

          is delocalised / free (to move) must be linked to electrons answers of delocalised / free electrons only, gains 1 mark accept each carbon is bonded to three other carbon atoms leaving delocalised / free electrons = 2 marks maximum 1 mark if graphite described as a metal / giant ionic lattice

1 [5]

 

M20.          (a)     2Mg + O2 → 2MgO

accept correct multiples / fractions 1

(b)    

  electrons do not need to be paired accept dots / circles / e instead of crosses do not allow 2.6 without diagram

1

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(c)    

  electrons do not need to be paired allow without bracket s/ must have the charge accept dots / circles / e instead of crosses ignore extra empty outer shells ignore nucleus

do not allow [2.8]2+ without diagram

1

(d)     oppositely charged (ions / atoms) allow positive and negative(ions / atoms)

1

          (they) attract must be in correct context accept held by electrostatic forces ignore ionic bonding maximum 1 if they refer to intermolecular forces / attractions / covalent bonds

1

(e)     magnesium chloride accept MgCl

2 (if correctly written)

1 [6]

 

M21.          high 1

          giant allow covalent

1

          four 1

          covalent 1

[4]

 

Page 92 of 121

M22.          (a)     (i)     

all three correct 2 marks one correct 1 mark

2

(ii)     14 1

(b)     A 1

[4]

 

M23.          (a)     2.8.3 on diagram as Xs / dots

          or e

accept paired or unpaired 1

(b)     any two from:

•        electrons in highest energy level or electrons in outer shell

•        electrons are delocalised or sea of electrons

•        electrons are free or electrons move around / flow

•        electrons carry charge / current ignore carry electricity

2 [3]

 

 

Page 93 of 121

M24.          (a)     bonding pair in the overlap and 6 other electrons arranged around the chlorine

must have either circles or symbols need not be pairs but must not be in the overlap region accept without H and Cl if clear accept all x’s or all o’s

1

(b)     H2         +         Cl

2 →  2HCl

accept multiples or fractions accept correct formulae but not balanced for 1 mark correctly balanced equation containing ‘correct’ lower / upper case symbols gets 1 mark

2

(c)     MgCl2

accept Mg2+(Cl-)2

1

(d)     because magnesium chloride is made of ions or is ionic

accept there are strong forces of attraction between the ions / particles in MgCl

2 or strong electrostatic attractions

accept more energy to separate particles in MgCl2

do not accept MgCl2 molecules

do not accept reference to breaking bonds 1

          hydrogen chloride is made of molecules or is covalent

accept there are only weak forces of attraction (between the particles / molecules) in HCl do not accept weak covalent bonds do not accept reference to breaking bonds do not accept MgCl

2 is a solid and HCl is a gas

1 [6]

 

Page 94 of 121

M25.          (a)     (i)      Quality of Written Communication The answer to this question requires ideas in good English in a sensible order with correct use of scientific terms. Quality of written communication should be considered in crediting points in the mark scheme.

maximum 2 marks if ideas not expressed well

         layers / lattice / giant structure / regular pattern of atoms (diagram) allow layers / lattice / giant structure / regular pattern of ions do not accept particles

1

         outer (shell) electrons accept valence electrons

1

         (free to) move (through whole structure) accept delocalised / mobile / free

1

(ii)     the free electrons (allow the metal to conduct electricity) accept electrons move / mobile / delocalised

1

(iii)     atoms / ions / layers can slide / slip / move over each other 1

(b)     (i)      copper oxide formed or Cu reacts with oxygen or Cu is oxidised 1

this is a poor conductor or gets in the way of free moving electrons or fewer mobile electrons

do not accept electricity 1

         or

         oxygen atoms / oxygen molecules / oxide ions in metal do not accept oxygen pockets / bubbles

         prevents / disrupts flow of electrons / current or fewer mobile electrons (1)

do not accept macro explanations do not accept electricity

(ii)     hydrogen reacts with oxygen or water is formed or hydrogen reduces copper oxide etc.

1 [8]

 

Page 95 of 121

M27.          (a)     Mr (SiO

2) = 60

if Mr incorrect ecf for max 2

1

          60 g SiO2 → 28 g Si

correct answer for 3 marks 1

          2.14 g SiO2 → 1 g Si

allow 2, 2.1, 2.14 (or anything rounding to 2.14), 2.16 or 2.2 a unit is not required but an incorrect unit loses the third mark

          OR Mr (SiO

2) = 60 (1)

          moles if silicon needed =  = 0.0357

          mass of SiO2 needed = 0.0357 × 60 (1)

          = 2.14 g (1) allow 2, 2.1, 2.14 (or anything rounding to 2.14), 2.16 or 2.2

          OR Mr (SiO

2) = 60 (1)

          mass SiO2 = 1 ×  (1)

          = 2.14 g (1) allow 2, 2.1, 2.4 (or anything rounding to 2.14), 2.16 or 2.2

3

(b)  (i)  MgO(s) + 2HCl(aq) → MgCl2(aq) + H

2O(l)

penalise incorrect symbols correctly balanced equation for 1 mark state symbols for 1 mark allow correct multiples / fractions

2

Page 96 of 121

(ii)    

         or

ignore inner shell electrons of silicon allow correct drawings without symbols must clearly indicate four shared pairs of electrons with one electron from each atom

(iii)        Si                       H

                             1

          = 0.05                 = 0.15 1

             1                        3 for whole number ratio can be implied

1

         Si H3

accept H3 Si or any correct formula with 1:3 ratio

if in step 1 they get either of ratios incorrect they lose first 2 marks but can be ecf for 3rd and 4th mark evidence of mass / A

r        1 mark

proportions of each         1 mark whole number ratio          1 mark correct formula                1 mark

1

Page 97 of 121

(iv)    C

accept c 1

(c)     any four from:

•        giant structure / macromolecule / lattice / giant molecule allow giant molecular / giant atomic structure

•        each silicon atom joined to four other atoms (or diagram)

•        covalent bonds

•        bonds are strong or large amount of energy needed to break bonds

accept hard to break bonds

•        large number of bonds to be broken mention of giant ionic structure or intermolecular forces or intermolecular bonds     max 1 mark diamond or carbon discussion max 3 marks unless clearly linked to silicon

4 [15]

 

M28.          answers apply to:

accept diagrams and/or descriptions

          carbon dioxide CO2

          ammonia NH3

          methane CH4

          water H2O

          *outer electronic structure of one atom correct or needs correct number of electrons to complete outer shell

1

          *outer electronic structure of other atom correct or needs correct number of electrons to complete outer shell

1

          *one shared pair of electrons (as one covalent bond)

use of ions or reference to ionic bonding negates this mark 1

          *outer electronic structure of compound correct or each atom now has a full outer shell/noble gas electron structure

1 [4]

 

Page 98 of 121

M29.          (i)      convection currents

accept a suitable description of convection currents 1

          move the Earth’s plates accept a suitable description of ‘movement’ of Earth’s plates

1

          at plate boundary one plate or a slab of rock can be pushed down forming magma/molten rock

accept at subduction zones magma/molten rock is formed – deconstructive boundary

1

          magma/molten rock rising and cooling at the Earth’s surface reforms as part of the plate

accept magma/molten rock rising and cooling at the Earth’s surface forms igneous rock – constructive boundary accept Earth’s crust or lithosphere for Earth’s surface

1

(ii)      isotopes are atoms of the same element do not accept that isotopes have the same atomic number but a different atomic mass

1

          19/the same number of protons 1

          19/the same number of electrons do not penalise for incorrect

1

          20 and 21 neutrons/different numbers of neutrons arithmetic if concept is correct

1 [8]

 

M30.          (a)     calcium atom loses two electrons

accept diagrams with correct labelling 1

(each) fluorine atom gains one electron accept two electrons transfer from a calcium atom to the two fluorine atoms for these first two marks

1

Page 99 of 121

forming full (outer) shells of electrons accept forming full (outer) energy levels or noble gas electronic structures do not accept stable unless qualified

1

giving the ions Ca2+ and F−

1

          attraction between ions of opposite charges accept electrostatic attraction between ions if candidate mentions sharing or pairing of electrons then no credit if explanation is entirely correct but they state this is called covalent bonding, the maximum mark is four

1

(b)     atoms of the same element 1

          atomic number is same accept each contains 92 or same number of protons

1

          mass numbers differ or each has a different number of neutrons 1

          one has 146 neutrons the other has 143 neutrons accept one has three more or less neutrons than the other

1

          (c)     (i)      349 1

(ii)     349g UF2 produces 235g U [1]

first mark can be awarded if answer is incorrect

answer = 117.5 1

[12]

 

M31.         (i)      same number of protons and electrons

accept equal numbers of protons and electrons do not accept they are neutral

1

Page 100 of 121

(ii)      same element accept all atoms are potassium

1

same number of protons accept same atomic number accept they all have 19+

1

different number of neutrons accept different mass numbers do not accept different atomic masses

1 [4]

   

M32.          (a)     (i)      H2SO

4 or red (acidic) pH < 7

accept names of compounds accept correct use of acidic

1

NaOH or purple (alkaline) pH > 7

alkaline and neutral without any mention of pH for 1 mark only 1

NaCl or green (neutral) pH 7

ignore high or low pH 1

(ii)     hydrogen (ion) accept proton accept hydroxonium ion

1

H+

accept H3O+ for hydroxonium ion

1

(b)     (i)      neutralisation 1

(ii)     NaOH + HCl ignore state symbols

1

NaCl + H2O

ignore state symbols maximum of 1 mark if incorrectly balanced

1

Page 101 of 121

(c)     (i)      sodium – 2 . 8 . 1 accept 2.8.1 written

1

chlorine – 2 . 8 . 7 accept 2.8.7 written

1

(ii)     ion(s) 1

(iii)     attraction between oppositely charged particles (ions) accept attraction between + and – particles (ions) accept electrostatic attraction

1

(d)     chloride ions lose electrons to form chlorine

Cl– –  e– → Cl 1

hydrogen ions gain electrons to form hydrogen

H+ +  e– → H

1

sodium hydroxide remains in solution

Na + and OH– remain in solution to form sodium hydroxide

1 [15]

 

M34.          (a)     (i)      H2SO

4 or red (acidic) pH < 7

accept names of compounds accept correct use of acidic

1

NaOH or purple (alkaline) pH > 7

alkaline and neutral without any mention of pH for 1 mark only 1

NaCl or green (neutral) pH 7

ignore high or low pH 1

(ii)     hydrogen (ion) accept proton accept hydroxonium ion

1

H+

accept H3O+ for hydroxonium ion

1

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(b)     (i)      neutralisation 1

(ii)     NaOH + HCl ignore state symbols

1

NaCl + H2O

ignore state symbols maximum of 1 mark if incorrectly balanced

1

(c)     (i)      sodium – 2 . 8 . 1 accept 2.8.1 written

1

chlorine – 2 . 8 . 7 accept 2.8.7 written

1

(ii)     ion(s) 1

(iii)     attraction between oppositely charged particles (ions) accept attraction between + and – particles (ions) accept electrostatic attraction

1

(d)     chloride ions lose electrons to form chlorine

Cl– –  e– → Cl 1

hydrogen ions gain electrons to form hydrogen

H+ +  e– → H

1

sodium hydroxide remains in solution

Na + and OH– remain in solution to form sodium hydroxide

1 [15]

 

M35.          (a)     any (must be named) 1

(b)     F2

1

(c)     –/F–

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1

(d)     (i)      covalent 1

(ii)     made of molecules etc. type of bonding when non-metals react.

1 [5]

 

M36.          (a)     (i)      14 electrons =

gets 1 mark

2.8.4 = gets 2 marks

2

(ii)     outer shell electrons 1

(iii)     same number of electrons in outer shell 1

(b)     (1)     shiny conducts electricity

(2)     oxide neutralises alkalis covalent bonds

4 [8]

 

M37.          (i)      electrons                                                                                                            1

for 1 mark

(ii)      covalent                                                                                                             1 for 1 mark

(iii)     made of small molecules: usually gas or liquid        ) dependent on have low melting points  ) having first have low boiling points   ) point above forces between molecules are weak

any 1 for 1 mark 3

[5]

 

M38.          (a)     8 marks       Particularly well structured answer with most points mentioned.

          7-6 marks    Well structured answer. The two metals will have been compared rather than simply listing advantages/disadvantages. Most of the advantages and disadvantages of each metal have been mentioned.

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          5-3 marks    Some structure to the answer.  An attempt to compare the metals by giving some advantages and disadvantages.

          2-1 marks    Little structure or attempt to compare.  Marks gained by listing a few advantages or disadvantages.

          Advantages of Nickel: Relatively low cost which makes the sparking plugs cheaper to produce. Quite high melting point which is needed because the temperature in the engine is very high. Good conductor of electricity needed to carry electricity into combustion chamber to produce spark.

          Disadvantages of Nickel: Subject to corrosion in engine which means they only last a short time because nickel is higher in reactivity than platinum. Idea that this leads to reduced efficiency, unburnt petrol and air pollution.

          Advantages of Platinum: Less susceptible to corrosion (not corroded) because platinum is very low in reactivity. Idea that this improves efficiency and reduces pollution.- Higher melting point than nickel to withstand the high temperatures in the combustion chamber. Last a lot longer than nickel electrodes due to low reactivity. (Sensible extension here could be longer service intervals etc.)- Good conductor of electricity as for nickel. Extension here could be linked to the idea that the conductivity does not deteriorate as quickly as nickel.)

          Disadvantages of Platinum: Cost which will make the sparking plug more expensive. A good candidate might justify cost by longer life, better fuel consumption and less pollution.

8

(b)     (i)      giant structure/lattice/regular arrangements of atoms any for 1 mark

         of atoms/of ions (provided free electrons mentioned) either for 1 mark

         delocalised or free electrons for 1 mark

3

(ii)     electrons free/can move for 1 mark each

2 [13]

 

M39.          (a)     2, 8, 8, 1

for 1 mark 1

Page 105 of 121

(b)     for 1 mark

Ignore symbol in middle but structure must be drawn NOT 2,7

          If covalent; can score mark for changes but not for diagram Arrow showing electron transfer from metal atom to non-metal atom = 2 marks If the ions are not identified then cannot score mark for changes

4 [5]

 

M40.          (a)     C16

H34

for 1 mark 1

(b)     electron gains 1 mark

          but shared electrons

gains 2 marks 2

[3]

 

##

          (a)     potassium / K for 1 mark

1

(b)     carbon dioxide / CO2

for 1 mark 1

(c)     losing electrons gaining electrons

for 1 mark each 4

Page 106 of 121

(d)     (i)      power supply, (not mains) beaker containing solution, (inert) electrodes and circuit ammeter or bulb/ (or see bubbling etc. at electrodes written by drawing)

for 1 mark each 4

(ii)     reading on ammeter/bulb lights / (solution) conducts (electricity) bubbling / gas produced hydrogen produced chlorine / oxygen produced ions move to electrodes (must be linked to ions move) negative ions move to the positive electrode and/or positive ions move to the negative electrode negative ions lose electrons and/or positive ions gain electrons

any  3 for 1 mark each 3

[13]

 

M42.          (a)     Group 2 / Alkaline Earth Metals

for 1 mark 1

(b)     (i)      MgCl2/Mg2+ (Cl–)

2

(or equation with correct answer) for 1 mark

1

(ii)     ionic / electrovalent for 1 mark

1 [3]

 

##

          (a)     covalent/description of covalent for 1 mark

1

(b)     forces/bonds between the molecules/particles (not atoms) are weak for 1 mark each

2

Page 107 of 121

(c)     non-flammable so it will not burn etc. extremely unreactive so it will not react with materials in the transformer, does not conduct electricity so it can insulate the transformer gas so it has freedom to move and insulate whole area

for 1 mark each 3

[6]

 

M44.          (a)     some electrons from outer shells (some electrons) free to move/mobile through whole structure/between atoms/sea of electrons hold atoms together

for 1 mark each

or positive ions in a sea of electrons (owtte) 2 marks

          atoms in regular structure/layers giant structure close packed credit diagrams – look for labels

for 1 mark each any 4 4

(b)     (i)      electrons, free to move (reference to electrons)

for 1 mark each 2

(ii)     layers/atoms can slide over each other for 1 mark

1

(iii)               free electrons hold atoms strongly together/strong forces of attraction/bonds (between atoms)/tight packing of atoms

for 1 mark 1

[8]

 

M45.          (a)     made of layers of carbon atoms weak forces of attraction between layers (owtte) / weak vertical bonds i.e. candidate refers to the diagram layers can slide over each other layers peel off

each for 1 mark

Page 108 of 121

(b)     because there are electrons which are free (to move) reason for free electrons / each carbon atom has 3 covalent bonds

each for 1 mark to max 5

[5]

 

M46.          (a)     X – (metal) atom / ion 1

Y – electron 1

(b)     free electrons or electrons move 1

(allow metal) atoms / ions to slide over each other

OR

bonding non - directional for 2 marks 1

[4]

 

M47.          (a)     proton + (1)

both required

neutron 1 both required

electron – (1) both required

3

(b)     2.8.3 accept words or diagram to this effect

1

          (c)     (i)      24 1

(ii)     52 1

Page 109 of 121

(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 1

(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

1

          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)

1

          (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

1 [10]

 

M48.          (i)      two

or 2 1

(ii)      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) 1

(iii)     2 1

(iv)     electrons accept charges

1

Page 110 of 121

(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]

 

M49.          (a)     (i)      sodium........ positive or +

both required 1

         chloride... negative or –

both required do not credit chlorine

1

(ii)     ions not free (to move) in solid crystal / lattice

ions are free to move when sodium chloride is molten 1

or ions are mobile

do not credit when ions are molten allow 'particles' for ions (1) mark do not credit electrons etc

1

Page 111 of 121

(iii)     dissolved in water or in aqueous solution accept in solution accept in water or when a gas/ vapour or solid it will not

1

(b)     (i)      40 1

(ii)     (total) number of protons and neutrons (in the nucleus) 1

(c)     (i)      2Ca + O2 -+ 2CaO

accept any 2n   :   n   :    2n ratio do not credit if any other change has been made

1

(ii)     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 (2)marks accept both electrons are lost from the atom for (1) mark

2 [10]

 

M50.          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

1

(ii)      sulphuric (acid) accept H

2SO

4

1

Page 112 of 121

(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'

1

(iv)     neutralisation accept neutralise accept neutral accept formation of salt or water do not credit exothermic

1 [4]

 

##

          (a)     positive for 1 mark

1

(b)     any reference to loss of electrons for 1 mark

          reference to charge being +2 (in (a)) or to loss of 2 electrons (in (b))

for 1 mark 2

[3]

 

M52.         (a)     same number/six electrons; same number/six protons; react in same way not same element or both carbon

any two for 1 mark each 2

Page 113 of 121

(b)     different number of neutrons gains 1 mark

but                                                      or

C     has two more neutrons              different mass number gains 1 mark

or

but two mass units bigger

gains 2 marks

C     has 8 neutrons while C    has 6 neutrons gains 2 marks

2 [4]

   

##

          (a)     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 1 mark 5

(b)     some electrons in the structure are delocalised/free to move for 1 mark

          these free electrons carry the electric current for 1 mark

          from left to right across the period, atoms of elements have more free electrons

gains 1 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 2 marks 4

[9]

 

                 

Page 114 of 121

M54.          (a)     correct representation of 1 atom of hydrogen e.g.

gains 1 mark

          but correct representation of 1 molecule of hydrogen e.g. or H-H

gains 2 marks

2

(b)     idea that: hydrogen/metals form positive ions/lose electrons

gains 1 mark

          but hydrogen and the metals form positive ions/lose electrons

gains 2 marks

          hydrogen/non-metals form covalent bonds/share electrons gains 1 mark

          but hydrogen and the non-metals form covalent bonds/share electrons

gains 2 marks 4

[6]

 

M55.         (a)     (i)      27

(ii)     13 each for 1 mark

2

(b)     each proton has a/1 positive charge and each electron has a/1 negative          charge OR electrons and protons have (equal but) opposite charges there are equal numbers of protons and electrons in the atom/           so charges cancel or balance (each other)

each for 1 mark 2

Page 115 of 121

(c)    

  each for 1 mark

3 [7]

   

PARTICLE NUMBER OF PROTONS

NUMBER OF NEUTRONS

NUMBER OF ELECTRONS

Fluorine atom   10  

Fluoride atom 9   10

M56.          (a)    

 

  for 1 mark each

3

  Calcium Phosphorus Fluorine

No of protons   15  

No of neutrons     10

No of electrons 20    

(b)     (i)      gain of electron(s)

         from (atoms) (of) calcium for 1 mark

2

(ii)     Ca+

gains 1 mark

         but superscript only Ca2+ / Ca ++

gains 2 marks 2

(c)     atoms electrons molecule(s)                      not compound

each for 1 mark 3

Page 116 of 121

(d)     (i)      ideas that

•        ionic – strong forces between ions

•        molecular – weak forces between molecules each for 1 mark

2

(ii)     ideas that

•        ionic – ions/charged particles are free to move

•        molecular -molecules do not carry a charge each for 1 mark

2 [14]

 

M57.          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 NH3

for 1 mark each [4]

 

M58.          (a)     2 Na + Cl2 → 2 NaCl 

allow 2 Na+ Cl– for 1 mark

(allow Na + ½Cl2 → Na Cl) 1

(b)     (i)      idea that

•        it has strong (attractive) forces/bonds between ions / charged particles for 1 mark

         (not ‘..it has a rigid structure’- this defines a solid or ‘...particles close together’ – they are in a liquid)

1

Page 117 of 121

(ii)     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 1 mark

2

(iii)     •        ions can go to electrodes / ions are free to move for 1 mark [do not credit ‘ions carry charges’]

1

(c)     ideas that

•        it has stronger attractive forces between atoms/particles (not ‘ions’)

•        each carbon atom forms covalent bonds with neighbouring atoms each for 1 mark

2 [7]

 

M59.         (a)     electrons neutrons protons

for 1 mark each 3

(b)     mass number           no. of neutrons        14                                8

for 1 mark each 2

[5]

   

Page 118 of 121

M60.          (a)     lithium = Li

(ignore mass / atomic numbers) fluorine = F   (do not allow if case is incorrect) for 1 mark each

2

(b)  (allow ● or o for electrons) (allow any positions for the seven electrons added provided they are on the outer ring)

for 1 mark 1

(c)           (2,8)+ or (2,7)–

(brackets not required) gains 1 mark

          but (2,8)–

gains 2 marks 2

[5]

 

M61.          (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

         (2 marks may be awarded for a correct electron diagram i.e. with electrons on boundary of or within marked area).

any two for 1 mark each 2

(ii)     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 1 mark each

2

Page 119 of 121

(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 1 mark each

2 [6]

 

M62.          (a)     idea that

•        copper has free electrons / electrons that move throughout the structure

gains 1 mark

          but

•        in copper, electrons from the highest (occupied) energy level /outer shell, are free / can move throughout the structure

gains 2 marks 2

(b)     idea that

•        in graphite, only three bonds are formed by each carbon atom for 1 mark

•        one outer electron (per atom), free to move for 1 mark

•        an electric current is a flow of (free) electrons* for 1 mark

          (* this mark to be given in either (a) or (b) but not in both) 3

[5]

 

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Page 121 of 121