Electron Configuration & Structure

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Darcy Harper
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1 Electron Configuration & Structure Mark Scheme Level Subject Exam Board Topic Sub Topic Booklet International A Level Chemistry Edexcel The Core Principles of Chemistry Electron Configuration & Structure Mark Scheme Time Allowed: 44 minutes Score: /36 Percentage: /100 Grade Boundaries: A* A B C D E U >85% 777.5% 70% 6.5% 57.5% 45% <45%

2 Correct Answer Reject Mark 1 D 1 Incorrect Answers: A There is no dative covalent bond B - There is no dative covalent bond C- There is no dative covalent bond Correct Answer Reject Mark D 1 Incorrect Answers: A Electron configuration lacks energy level 3 electrons B - Electron configuration has an extra 18 electrons C- E ctron configuration lacks energy level 3 electrons Correct Answer Reject Mark 3 B 1 Correct Answer Mark 4 D 1 Correct Answer Mark 5 B 1 Correct Answer Mark 6 C 1

3 Correct Answer Mark 7 A 1 Correct Answer Mark 8 C 1 Correct Answer Reject Mark 9 D 1

4 10(a)(i) Arrows correct half-headed arrows/ 3p electrons all pointing downwards Labels correct p x, p y, p z and 3p x, 3p y, 3p z IGNE numbers as superscripts 10(a)(ii) Mark independently First mark (idea of paired electrons in S) In sulfur: spin-pairing has occurred (in the 3p orbital / sub-shell)/ there are paired electrons (in a 3p orbital / sub-shell ) there are two electrons in the same (3p) orbital / there is a full (3p) orbital Sub-shell / shell Note Just stating 3p 4 does not get this mark Second mark (idea of repulsion) (Resultant increase in) repulsion (allows electron to be removed more easily) Note if no correct reference to sulfur Phosphorus has a half-filled sub-shell which is (more) stable IGNE any reference to nuclear attraction / atomic radius / shielding

5 10(a)(iii) P + (g) P 3+ (g) + e (-) Incorrect symbol for P + (g) e (-) P 3+ (g) first mark only +/+3 for +/3+ or additional electrons provided the equation balances Correct symbols Both (g) Mark independently IGNE state symbol on the electron / IE in equation 10(b)(i) Mark independently 3 First mark (number of shells) N has fewer (electron) shells than P The outer electron is in a shell closer to the nucleus in N In N the atomic radius/size is less Mention of molecules Just lower atomic number / N is smaller than P Ionic radius Second mark (shielding) (Outermost electron in N) has less shielding Third mark (attraction) (Even though N has a lower nuclear charge/ fewer protons) (there is a) greater (force of) attraction between the nucleus and the (outer) electron/ greater effective nuclear charge outer electron is held more strongly by the nucleus N has a higher nuclear charge than P IGNE N has a greater charge density Reverse argument for phosphorus / trend down the group

10(b)(ii) all dots, all crosses or any other symbol for the electrons First Mark Three pairs of electrons between the nitrogen atoms Two or three of the 3 pairs of electrons circled to show sharing

6 10(b)(ii) all dots, all crosses or any other symbol for the electrons First Mark Three pairs of electrons between the nitrogen atoms Two or three of the 3 pairs of electrons circled to show sharing as part of triple bond Second Mark Lone pair on each nitrogen atom unpaired electrons 10(c) Correct answer with or without working scores both marks of moles = x 4 = 0.(00) (mol) of molecules of P 4 = 0. x 6.0 x 10 3 = 1.04 x 10 3 / 1.0 x 10 3 / 1. x 10 3 TE on number of moles IGNE SF except 1SF (Total for 10 = 13 marks)

7 11(a) s-orbital p-orbital (s-orbital) Circle drawn Concentric circles drawn (p-orbital) Figure of 8 / dumb-bell drawn NOTE: p-orbital can be drawn along any axis (axis does not have to be shown) If one, two or three p-orbitals of correct shapes are shown If overlapping orbitals are shown of correct shape in both cases, award mark 11(b) (region) (no. of electrons) 3 (a d-orbital) (a p sub-shell) (the third shell) 6 18

8 11(c) First mark: BOTH s and p labelled p 6 s and p 4 Second mark: ALL eight e shown correctly p energy s (1s) Half-arrows or full arrows for each electron Paired arrows in any one of the p orbitals NOTE Single arrows must be orientated in same direction Paired arrows must have opposite spins

9 11(d)(i) First mark: 3 Makes mention of energy/enthalpy/(heat) energy/heat (change/required) Energy given out for first mark AND to remove an electron Second mark: one mole/1 mol Third mark: Makes mention of gaseous atom(s) Just gaseous element / gaseous substance ALTERNATIVE ANSWER Energy change per mole / kj mol 1 for X(g) X + (g) + e ( ) () One mark for species One mark for correct state symbols Mark independently IGNE any references to standard conditions

10 11(d)(ii) O + (g) e O 3+ (g) Reverse equation scores (0) overall O + (g) O 3+ (g) + e All species and balancing correct State symbols correct nd mark is dependent on 1 st mark e for e IGNE (g) the e

11 11(d)(iii) First mark: Big jump / large increase Second mark: between 6th and 7th (IE) after the 6 th Any other ionization jumps mentioned to the 7 th from 1337 to of IGNE Additional jump identified between 4th and 5th (IE) if justified in terms of a change of sub-shell Additional jump identified between 4th and 5th (IE) if justified in terms of NOT being a change of shell (Total for 11 = 14 marks)

Periodicity & Trends

Periodicity & Trends Mark Scheme 1 Level Subject Exam Board Topic International A Level Chemistry Edexcel The Core Principles of Chemistry Sub Topic Periodicity & Trends Booklet Mark Scheme 1 Time Allowed: