Metals and Non-metals

Elements can be broadly classified as metals and non-metals on the basis of their properties. Metals such as iron, copper and aluminium are generally lustrous, hard, malleable, ductile, sonorous and good conductors of heat and electricity, while non-metals such as carbon, sulphur and oxygen are mostly brittle and poor conductors. You will also meet the exceptions: mercury is a liquid metal, sodium can be cut with a knife, iodine is lustrous and graphite conducts electricity. In this chapter you will study how metals react with oxygen, water and acids, identify amphoteric oxides like aluminium oxide, and arrange metals in a reactivity series from potassium to gold. You will learn how metals and non-metals react by transferring electrons to form ionic compounds such as NaCl and MgCl2, and the properties of these compounds. You will then study the occurrence of metals, the extraction of metals of low, medium and high reactivity by roasting, calcination, reduction and electrolysis, electrolytic refining, and the prevention of corrosion by galvanising and alloying.

Detailed Worksheet: Metals and Non-metals Section A - Definitions (10 marks) 1. List four physical properties of metals and give one exception to each. (2 marks) 2. What are amphoteric oxides? Give two examples. (2 marks) 3. What is the reactivity series of metals? Arrange Na, Cu, Zn, Fe and Au in decreasing order of reactivity. (2 marks) 4. Define the terms mineral, ore and gangue. (2 marks) 5. What is an alloy? Name the constituents of brass, bronze and solder. (2 marks) Section B - Calculations and Applications (15 marks) 6. Write balanced chemical equations for the reactions of (i) sodium with water (ii) aluminium oxide with hydrochloric acid (iii) aluminium oxide with sodium hydroxide. (3 marks) 7. In the thermit reaction, iron(III) oxide is reduced by aluminium. Write the balanced equation and calculate the mass of iron obtained from 16 kg of iron(III) oxide. (Fe = 56, O = 16, Al = 27) (3 marks) 8. Pure gold is 24 carat. Jewellery is usually made of 22 carat gold. Calculate the percentage of gold in 22 carat gold and the mass of pure gold in a 12 g ornament of 22 carat gold. Why is pure gold not used for jewellery? (3 marks) 9. Zinc is obtained by reducing zinc oxide with carbon. Write the balanced equation and calculate the mass of zinc produced from 162 g of zinc oxide. (Zn = 65, O = 16, C = 12) (3 marks) 10. Write the electron-dot structures for sodium, oxygen and magnesium. Show the formation of Na2O and MgO by the transfer of electrons. (Atomic numbers: Na = 11, O = 8, Mg = 12) (3 marks) Section C - Diagrams (10 marks) 11. Draw a labelled diagram of the apparatus to study the action of steam on a metal, showing the metal sample, glass wool soaked in water, burner, delivery tube and gas collected over water. Write the equation for the reaction of iron with steam. (4 marks) 12. Draw a labelled diagram of the electrolytic refining of copper, showing the impure copper anode, pure copper cathode, acidified copper sulphate solution and anode mud. (3 marks) 13. Draw a flow chart showing the steps involved in the extraction of metals of low, medium and high reactivity from their ores. (3 marks) Section D - Analysis and Higher-order Thinking (15 marks) 14. An element A forms an oxide A2O3 which is acidic in nature, while an element B forms an oxide BO that is basic. Identify whether A and B are metals or non-metals. Why is aluminium used to make cooking utensils even though it is a highly reactive metal? Explain the role of its oxide layer. (5 marks) 15. Explain why sodium is stored under kerosene, why calcium floats when it reacts with water, and why metals like copper do not react with dilute hydrochloric acid. Which gas is produced when a metal reacts with nitric acid, and why is hydrogen not usually evolved? (5 marks) 16. Iron articles corrode quickly in a coastal town. Describe an activity with three test tubes to show the conditions necessary for the rusting of iron. Explain how galvanisation and alloying help to prevent corrosion, and why stainless steel does not rust. (5 marks) Instructions: Time allowed 2 hours. Attempt all sections. Write balanced chemical equations with state symbols wherever possible. Draw all diagrams neatly and label every part.