NJC Suggested solution of Physical Periodicity tutorial solution (student)

National Junior College SH1 H2 Chemistry 1 Success Criteria Relevant Tutorial questions What do you still struggle with? Write your queries here. 1. I can recognize the variations in the valence electronic configuration across the Period and down a Group. DQ5 2. I can apply an understanding of nuclear charge, shielding effect and number of filled electronic shells from nucleus to account for the nuclear attraction. 3. (a) I can describe and explain qualitatively the trends and variations in (I)atomic radius, (II)ionic radius, (III)first ionisation energy and (IV)electronegativity: (i) across a Period (same valence electronic shell) in terms of shielding effect and nuclear charge; (ii) down a Group (increasing number of filled electronic shell) in terms of shielding, distance away from nucleus and nuclear charge. (b) I can predict and explain the variations in ionic radius for species with either same number of electrons (e.g. isoelectronic species, Na+, Mg2+) or same number of protons (e.g. Na vs Na+) using proton to electron ratio to account the nuclear attraction for the outermost electrons. (a)(I):SAQ1, DQ3b (II): DQ2b, DQ3c, DQ4b(i)/(iii) (III): DQ5 (IV): DQ7d (b): DQ2a, DQ3a, DQ6b 4. (a) I can sketch, descr ibe and explain the first ionisation energy trend across a Period 2 or 3 and down a group by referring to their valence electronic configuration. (b) I can explain the anomalous trend in first ionisation energy for elements with valence electronic configuration of (i) ns2 vs ns 2 np1 in terms of most loosely held electron in a higher energy p subshell (ii) ns 2 np3 vs ns 2 np4 in terms of interelectronic repulsion between paired electrons in p orbital (a): DQ4a, DQ5 (b)(i): DQ4b(ii), (b)(ii): DQ4b(iv)

National Junior College SH1 H2 Chemistry 2 General answering approaches to the questions Step 1: Write down the electronic configuration of the respective species Step 2: Compare the no. of protons (p) and electrons (e) between the species: • If either e or p has the same number, use p to e ratio to compare the nuclear attraction on the outermost electron. (skip Step 3 and continue with Step 4) • If both e and p changes at the same time, comment on the nuclear charge (continue with Step 3) Step 3: Compare the number of filled electronic shell to comment on the shielding effect and the distance from the nucleus Step 4: State the strength of the nuclear attraction on (i) outermost electrons (atomic radius / ionic radius) (ii) most loosely held electron (ionisation energy) (iii) bonding electrons (electronegativity) Step 5: Relate to its physical