Periodicity Worksheet 1 Answers

Periodicity (Suggested answer) 1 (a) X3+ (g) → X4+ (g) + e

4th Ionisation energy

(b)(i)

A

(ii)

B

C

D E F G Successive elements

H

I

J

E = Aluminum. The difference between 4th electron remove shows that E3+ valence configuration is ns2 np6, while F3+ is (n+1)s1. Therefore, the valence electron configuration of E is (n+1)s2 (n+1)p1. (Cannot use Aluminum as the starting point.)

(c)

(iii)

B = Neon, J = Argon. (Need to identify)

(i)

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G: removing electron from s subshell, H: removing electron from a p subshell (from same valence shell.)

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The s-subshell is closer to the nucleus than the p-subshell. Electron in the s-subshell, experience greater nuclear attraction than electron in the p-subshell.

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Hence, more energy is needed to remove the electron. thus higher 4th IE.

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(iii) ƒ

B removing electron from a lower principal quantum shell, while C removing electron from a higher principal quantum shell.

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The lower principal quantum shell is closer to the nucleus. Electrons in it experiences greater nuclear attraction.

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More energy is required to remove the electron, hence higher 1st IE.

(d) ƒ

Structure: D – Giant Metallic Lattice structure. Structure, H and J – Simple discrete molecule.

F – Giant Covalent

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Bonds that breaks during melting: D – electrostatic attraction between cation and sea of delocalized electrons. F – Covalent bonds, H and J – van der Waals interaction.

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Breaking of inter-atomic bonding requires more energy than van der Waals interaction, hence D and F have higher mp than H and J.

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D vs F – more dm3 of bonds are broken in F than in D and hence results in F to have a higher mp.

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H vs J – H exists as S8, larger electron cloud and hence more polarisable. Stronger id-id.

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Conductivity – D is a metal contains sea of delocalized electron. F – semi-conductor, some electrons that can be delocalized to conduct electricity. H and J do not have charge carriers.

(e) (i) (iii)

Al2Cl6 (aluminum chloride is not accepted, neither is AlCl3) Al2Cl6 (g) → 2AlCl3 (g) As V is a constant, P α n.

(f)

Trend : F, H and G. Si (s) → Si (g); ⅛S8 (s) → S (g); ¼P4 (s) → P (g) Si - Giant covalent structure, extensive network of covalent bond. S8 – one mole of S8 breaks 8 moles of S – S bond. P4 – one mole of P4 breaks 6 moles of P – P bond. More bonds are broken in atomization of Si, than P than S (based of atomization equation.)

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