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Edexcel Jan 2012 Paper 1 Q23
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![Question Number *23(a) Mark Acceptable Answers Reject ALLOW reverse arguments in each case Any three from:-sodium atoms/sodium ions are larger (than magnesium atoms/ions) NOTE: Allow symbols (eg Na or Na+ ) (1) sodium ions are Na+ whereas magnesium ions are Mg2+ OR Na+/sodium ions have smaller charge (density) than Mg2+/ magnesium ions (1) [NOTE: It follows that the statement that Na+ ions are larger than Mg2+ ions would score the first two scoring points above)] sodium has fewer delocalized electrons (than magnesium) Attraction between nucleus and (delocalized) electrons Mention of intermolecular forces/molecules negates the energy mark NOTE: Arguments based on ionization energies OR suggestion of removal of outer shell electrons as part of the melting process scores (0) overall (1)attraction between the positive ions and (delocalized) electrons is weaker in sodium (than magnesium) (1) sodium is not close-packed (but magnesium is close-packed) (1) less energy needed (to break bonds) (1) 6CH0101 1201<br />
Question Number *23(b) Acceptable Answers Reject Mark First mark: Idea of (breaking) covalent bonds in silicon (1) Second and third marks: ANY TWO FROMSilicon is giant covalent / giant atomic/giant molecular/ macromolecular/giant structure/giant lattice IGNORE just giant (1) Intermolecular forces broken in silicon/ covalent bonds broken in phosphorus silicon giant ionic/silicon giant metallic Weak bonds between phosphorus atomsPhosphorus made up of simple molecules /small molecules/ P4 molecules /phosphorus is molecular covalent /molecular/simple covalent IGNORE just simple/simple structure (1)Between phosphorus molecules: weak forces/weak intermolecular forces/weak London forces/weak van der Waals forces/weak dispersion forces/weak induced-dipole forces (1) [ALLOW weak bonds if implies between phosphorus molecules]More energy needed (to break bonds in silicon) (1) 6CH0101 1201<br />
Question Number *23(c) Question Number *23(d) Mark Mark Acceptable Answers Reject IGNORE any references to energy in this part of the question Argon monatomic/argon (composed of) single atoms NOTE: This must be stated in words, not just by use of its symbol Ar IGNORE any comments about argon atoms having a full outer shell or argon being a noble gas IGNORE any comment about forces/bonds between argon particles Any suggestion that argon is molecular Argon having a giant structure (of atoms) Acceptable Answers Reject First mark: Mg has mobile electrons/delocalized electrons/free electrons/sea of electrons (to carry the charge) ALLOW Mg2+ instead of Mg or magnesium (1) Second mark: Sulfurs electrons are fixed (in covalent bonds)/sulfurs electrons are involved in bonding/sulfurs electrons are not free (to move)/no delocalized electrons in sulfur/no mobile electrons in sulfur (1) Mg has free ions/Mg has mobile ions Sulfur has no free ions/sulfur has delocalized electrons/just sulfur has covalent bonds/ just sulfur is not a metal 6CH0101 1201<br />](https://learnah.org/wp-content/uploads/2018/08/January_2012_MS_-_Unit_1_Edexcel_Chemistry_A-level_23-0.jpg)
