8 3 Ammonia reacts with sodium to form sodium amide, NaNH2 , and hydrogen. (a) (i) Write the equation for this reaction. State symbols are not required. (1) (ii) Draw diagrams showing the 3-dimensional shape of an ammonia molecule and of an amide ion, NH2 –. Include any lone pairs of electrons in each species. (3) ammonia molecule amide ion (iii) What is the H–N–H bond angle in an ammonia molecule? (1) A 104.5° B 107° C 109.5° D 120° Turn over 9 (iv) Explain the difference between the H–N–H bond angle in ammonia and in the amide ion. (2) .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... (b) Give a possible reason why samples of sodium amide are stored in oil. (1) .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... (Total for Question 3 = 8 marks)