Edexcel Jun 2011 Paper 1 Q20 (with explained solutions) |

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Edexcel Jun 2011 Paper 1 Q20

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20 Metals are good conductors of heat and electricity and usually have high melting temperatures and boiling temperatures. (a) (i) Describe the structure of a metal. PMT (2)(ii) Describe the bonding in a metal. (2)(b) Explain why the melting temperature of magnesium (650 C) is much higher than that of sodium (98 C). (3)20 *P38433A02024*<br />
(c) Explain how metals conduct electricity. PMT (2)(Total for Question 20 = 9 marks) TOTAL FOR SECTION B = 60 MARKS TOTAL FOR PAPER = 80 MARKS *P38433A02124* 21<br />

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Question Number 20 (a) Question Number 20 (b) Mark Mark Acceptable Answers Reject layers protons free electrons (i) Structure Lattice /close-packed (1) (or a diagram with at least 3 rows) positive ions or cations (allow metal ions) (1) delocalized electrons / sea of electrons (1) (ii) Bonding (Electrostatic) attraction between positive ions / cations (allow metal ions) and delocalized electrons / sea of electrons (1) Acceptable Answers Reject Just Mg2+ and Na+ More bonds Any three from 1. Magnesium ion / Mg2+ (allow magnesium) has a larger charge (density) than the sodium ion (allow sodium) / Na+ some comparison of the ions is required (1) 2. magnesium ions / Mg2+ smaller than sodium ions (1) 3. Magnesium / Mg2+ contributes two / more electrons (per atom) to the sea of electrons (1) 4. magnesium ions / Mg2+ have greater attraction for the delocalized sea of electrons (1) Ignore reference to number of outer electrons in Mg / Na Any references to the bonding being ionic, covalent or intermolecular (max 2) Reverse argument can gain full marks 6CH0101 1106<br />
Question Number 20 (c) Acceptable Answers Reject free electrons The delocalized electrons / sea of electrons (1) Flow (allow move / free to move) (1) (When a potential difference/voltage is applied) Carry the current is not sufficient for the mark Mark TOTAL FOR SECTION B = 60 MARKS 6CH0101 1106<br />

Question 16 17 18 19 20

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