Q. (a) Read a student s report about the reaction between sodium and water. The reaction between sodium and water A small piece of sodium was added to some water in a trough. The sodium floated and started to react. The sodium moved along the surface of the water and melted to give a ball of molten metal. The ball became smaller and smaller until it had all gone. A gas was given off and a colourless solution was left. The word equation for this reaction is: sodium + water sodium hydroxide + hydrogen Use the information from the student s report to answer these questions. (i) Which information shows that sodium has a low density?... () Which information shows that the reaction is exothermic?... () (iii) Name the gas given off.... () (b) The periodic table on the Data Sheet may help you to answer these questions. (i) Sodium is in Group. Name a Group element that is more reactive than sodium.... () Page of 8
Here are some statements about Group elements. Only two of these statements are correct. Put a tick ( ) next to the two correct statements. Statement ( ) They are halogens They are metals They form covalent compounds They form ions with a + charge (2) (c) Dimitri Mendeleev put forward his periodic table in 869. Complete these sentences by drawing a ring around the correct answer. (i) Mendeleev arranged the elements in order of their atomic weight density reactivity () The table is called a periodic table because elements with properties occur at regular intervals. identical the same similar () (iii) The vertical columns are known as groups periods rows () (d) How did Mendeleev overcome the problem of undiscovered elements when he designed his table?... () (Total 0 marks) Page 2 of 8
Q2. X is an element with the following properties: melts at 220 C and boils at 88 C; does not conduct electricity at room temperature; forms molecular compounds with non-metals; forms ionic salts with metals in which its ion has a charge. (a) Would you expect X to be a solid, a liquid or a gas at 20 C?... () (b) Predict the formula of the product formed when X reacts with aluminium. (The aluminium ion is Al 3+ and the X ion is X.) Select your answer from the list below. AlX AlX 2 AlX 3 Al 3 X Al 2 X 3 Predicted formula... () (c) To which Group of the Periodic Table does the element X belong?... () (Total 3 marks) Q3. Sodium and potassium are both in Group of the Periodic Table. (a) Explain, by reference to their electronic structures, why both elements are placed in Group....... () Page 3 of 8
(b) Use the Data Sheet to help you to answer this question. The diagrams below represent the electronic structures of some atoms and ions. Which one of the structures, A - F (i) represents a sodium atom,... represents a potassium ion?... () () (c) Sodium and potassium both react with cold water. (i) The word equation represents the reaction of sodium with water. sodium + water sodium hydroxide + hydrogen Complete and balance the symbol equation for this reaction.... +... 2NaOH +... (2) Page 4 of 8
How does the reactivity of potassium with water differ from that of sodium with water? Explain this difference in reactivity by reference to the electronic structures of the potassium and sodium atoms. (4) (Total 9 marks) Page 5 of 8
M. (a) (i) floated / (moved on) surface accept does not sink ignore it melted melted / molten ignore heat is given off (iii) hydrogen allow H 2 (b) (i) potassium / rubidium / caesium / francium accept: K / Rb / Cs / Fr they are metals they form ions with a + charge (c) (i) atomic weight (iii) similar groups (d) left gaps owtte [0] M2. (a) gas for mark (b) AlX 3 for mark (c) 7 / halogens for mark [3] Page 6 of 8
M3. (a) same number of electrons in outer shell / / an electron in outer shell / lose one electron for mark (b) (i) C for mark E for mark (c) (i) 2Na + 2H 2 O 2NaOH + H 2 symbols must be correct correct multiples / fractions accepted Balancing mark is independent formulae gains mark balancing gains mark 2 Assume it means potassium potassium more reactive / vigorous / faster reaction / violent (can be awarded in either section) potassium atom larger than sodium / higher outer energy level / outer shell further from nucleus / more shells (not just more electrons) electron in outer shell is less strongly attracted / greater shielding outer electron more easily lost for mark each 4 [9] Page 7 of 8
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