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Edexcel Jun 2013 Paper 1 Q19
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![19 This question is about the elements arsenic to rubidium which have atomic numbers 33 to 37. The first ionization energies, Em1, of these elements are given in the table. Element Em1 / kJ mol1 As 947 Se 941 Br 1140 Kr 1351 Rb 403 (a) Write the equation, with state symbols, which represents the first ionization energy of arsenic. (b) Suggest the formulae of the hydrides of arsenic and selenium. (c) (i) Complete the electronic configuration for an arsenic and a selenium atom using the electrons-in-boxes notation. As Se [Ar] 3d10 [Ar] 3d10 4s np np 4p (2) (2) (2) 10 *P41649A01024*<br />
*(ii) Explain why the first ionization energy of selenium is lower than that of arsenic. (2)*(d) Explain why the first ionization energy of krypton is higher than that of selenium. (2)*(e) Explain why the first ionization energy of rubidium is lower than that of krypton. (2)(f) Which of the elements, arsenic to rubidium, is likely to have atoms with the smallest atomic radius? (1)(Total for Question 19 = 13 marks) *P41649A01124* 11 Turn over<br />
BLANK PAGE 12 *P41649A01224*<br />](https://learnah.org/wp-content/uploads/2018/08/l_smalljpgJune_2013_QP_-_Unit_1_Edexcel_Chemistry_A-level_19-0.jpg)
![Mark Acceptable Answers Reject As(g)e() As+(g) OR As(g) As+(g) + e() Entities (1) All species gaseous (1) providing a reasonable attempt at an ionization energy Examples: As(g) + e() As+(g) As(g)e() As-(g) As2+(g)e() As3+(g) IGNORE state symbol of electron ALLOW upper case / large S in arsenic ALLOW As(g) + e() As+(g) + 2e() (2) As(g)+e() As-(g) (electron affinity) Acceptable Answers Reject Mark AsH3 / H3As (1) H2Se / SeH2 (1) IGNORE charges ALLOW upper case / large S in arsenic NOTE: If two or more answers given for one element mark that element on a plus minus basis SE for Selenium Question Number 19(a) Question Number 19(b)<br />
Acceptable Answers Reject As Se [Ar] 3d10 [Ar] 3d10 4s4pOne mark for each row Arrows may be half-headed Arrows must be in same direction if in singly occupied boxes (can be down) ALLOW two arrows for Se in any 4p box Selenium two arrows must show opposite spins Question Number 19(c)(i) Mark<br />
Question Number 19(c)(ii) For parts c(ii),d and e it is important Acceptable Answers Reject to keep in mind the two elements involved in each part As and Se First mark: EITHER In Se, (spin) pairing has occurred (for the first time in that p sub-shell) OR electron removed from orbital containing two electrons (1) ALLOW sub-shell for orbital Second mark: EITHER (Increase in) repulsion (so electron lost more easily) OR Half-filled (sub-) shell/allow orbital (particularly) stable (in As) ALLOW orbital for sub-shell (1) Mark each point independently IGNORE reference to distance from nucleus and shielding Mark<br />
Question Number 19(d) Acceptable Answers Reject Mark Se and Kr First mark: EITHER The nuclear charge is increasing (Nuclear must be stated or clearly implied ) OR number of protons / atomic number is increasing (1) Second mark: (Outermost) electron closer to nucleus / electron is removed from the same (sub)shell / electron experiences similar shielding / (atomic) radius is smaller/ smaller atom (1) ALLOW reverse arguments for selenium IGNORE Kr has full outer shell Ionic radius Molecule (unless monatomic)<br />
Acceptable Answers Reject Mark Kr and Rb Any two from: The electron (in Rb) (removed) is further from the nucleus (1) The electron is in a higher / new / another / 5s (energy quantum) shell / energy level (1) More shielded (1) IGNORE any reference to stability of krypton or larger atomic radius of Rb / full outer shell of Kr It is possible that two answers may be offered together in one sentence e.g. Rb outer electron is in another shell further from nucleus (2) Acceptable Answers Reject Mark Krypton / Kr Anything else Total for Question 19 = 13 Marks Question Number 19(e) Question Number 19(f)<br />](https://learnah.org/wp-content/uploads/2018/08/June_2013_MS_-_Unit_1_Edexcel_Chemistry_A-level_19-0.jpg)
