2024 H1 Chem Prelim P2 Ans_VJC

© VJC 2024 8873/02/PRELIM/24 [Turn over CANDIDATE NAME CT GROUP VICTORIA JUNIOR COLLEGE JC 2 PRELIMINARY EXAMINATION Higher 1 ……………………………………………….………….. …………………………….. CHEMISTRY 8873/02 Paper 2 Structured Questions Candidates answer on the Question Paper. 12 September 2024 2 hours Additional Materials: Data Booklet READ THESE INSTRUCTIONS FIRST Write your Name and CT group in the spaces at the top of this page. Write in dark blue or black pen. You may use a HB pencil for any diagrams or graphs. Do not use staples, paper clips, glue or correction fluid. Section A Answer all the questions. Section B Answer one question. The use of an approved scientific calculator is expected, where appropriate. The number of marks is given in brackets [ ] at the end of each question or part question. For Examiner’s Use Section A 1 / 16 2 / 25 3 / 19 Section B 4 / 5 / 20 Total / 80 This document consists of 23 printed pages.

2 © VJC 2024 8873/02/PRELIM/24 Section A Answer all questions in this section in the spaces provided. 1 (a) (i) Write down the electronic configurations of the following species. • Na :1s22s22p63s1 • Al2+ : 1s22s22p63s1 [1] (ii) The electronic configuration of copper atom is 1s22s22p63s23p63d104s1. Sketch the shape of the filled orbital of copper atom with the highest energy on the axes in Fig. 1.1 and label the orbital. • Fig. 1.1 [1] (iii) Write a balanced equation for the third ionisation energy of aluminium. • Al2+(g) → Al3+(g) + e– [1] (iv) Explain why the third ionisation energy of aluminium is greater than the first ionisation energy of sodium. • Al2+ has a greater nuclear charge than Na as it has more protons. The shielding effect is the same for both A l2+ and Na as both have the same electronic configuration (OR number of electrons). • Hence, A l2+ has a greater effective nuclear charge leading to a greater third ionisation energy than the first ionisation energy of sodium. [2] 4s

3 © VJC 2024 8873/02/PRELIM/24 [Turn over (b) Period 3 elements and their compounds show trends in their physical and chemical properties. (i) Sketch a graph to show the melting points of the first five elements in Period 3 on Fig. 1.2. Fig. 1.2 1m: Na, Mg and Al (increasing trend), 1m: Si (highest) and P (lowest) [2]