Q. Hydrogen chloride (HCl) can be made by the reaction of hydrogen (H 2) 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. () (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..... () Page
(d) Why does magnesium chloride have a much higher melting point than hydrogen chloride?.............. (2) (Total 6 marks) Q2. Ammonia (NH 3) is an important chemical which is used to make fertilisers. Ammonia is made from nitrogen and hydrogen, (a) The diagrams represent the electron arrangements in atoms of nitrogen and hydrogen. Complete the diagram showing the arrangement of electrons in a molecule of ammonia. () Page 2
(b) Name the type of bonding which holds the nitrogen and hydrogen atoms together in an ammonia molecule.. () (Total 2 marks) Q3. (a) A piece of lithium is placed on the surface of some water in a beaker. Hydrogen is given off. Lithium hydroxide is also formed. Write a word equation for this reaction.. (2) (b) The diagram shows the structure of a molecule of methane. Write down everything that this diagram tells you about a methane molecule. To gain full marks in this question you should write your ideas in good English. Put them into a sensible order and use the correct scientific words.................. (4) (Total 6 marks) Page 3
Q4. 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............................ (Total 4 marks) Q5. Sodium reacts with chlorine to form the compound sodium chloride. 2Na + Cl 2 2NaCl Describe, in terms of electron arrangement, the type of bonding in: (i) a molecule of chlorine;...... Page 4
(3) (ii) the compound sodium chloride.......... (4) (Total 7 marks) Page 5
M. (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 (b) H 2 + Cl 2 2HCl accept multiples or fractions accept correct formulae but not balanced for mark correctly balanced equation containing correct lower / upper case symbols gets mark 2 (c) MgCl 2 accept Mg 2+ (Cl ) 2 (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 MgCl 2 do not accept MgCl 2 molecules do not accept reference to breaking bonds 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 Page 6
do not accept reference to breaking bonds do not accept MgCl 2 is a solid and HCl is a gas [6] M2. (a) all electrons correct (inner shell need not be shown) three bond pairs and two electrons anywhere else can use dots, crosses or e s in any combination (b) covalent accept phonetic spelling do not accept convalent [2] M3. (a) LHS lithium + water accept Li and H 2O accept hydrogen oxide for water RHS hydrogen + lithium hydroxide accept H 2 and LiOH ignore attempts at balancing ignore charges (b) Quality of written communication One mark for the correct use of any three of the terms atom, covalent, bond(ing), saturated, hydrocarbon or alkane any three from: Page 7
one / the carbon (atom) reject molecules once four hydrogen (atoms) shape / properties neutral CH 4 hydrocarbon saturated / single bond covalent bond / shared electrons alkane reject ionic bond 3 [6] M4. answers apply to: accept diagrams and/or descriptions carbon dioxide CO 2 ammonia NH 3 methane CH 4 water H 2O *outer electronic structure of one atom correct or needs correct number of electrons to complete outer shell *outer electronic structure of other atom correct or needs correct number of electrons to complete outer shell *one shared pair of electrons (as one covalent bond) use of ions or reference to ionic bonding negates this mark *outer electronic structure of compound correct or each atom now has a full outer shell/noble gas electron structure Page 8
[4] M5. (i) can be from diagram chlorine (2.8).7. accept chlorine needs one more electron can be from diagram shares a pair of electrons shared pair of electrons is a covalent bond do not accept ionic bond (ii) can be from diagram and appropriately annotated sodium (2.8).. and chlorine (2.8).7 sodium loses one electron and chlorine gains one electron Na + and Cl formed bond formed between oppositely charged ions or ionic bond is formed do not accept covalent bond [7] Page 9