1 More about Metals Physical properties of metals In general metals have luster, are malleable and ductile, good conductors of heat and electricity and have high boiling and melting points and nonmetals the opposite. The following metals and nonmetals do not follow the general trend. Can you identify what is different or special about them? Element Carbon and it s allotropes (graphite and diamond) Mercury, Cesium and Gallium Alkali metals Manganese and Mercury Physical property which stands out Chemical properties of metals Reaction with oxygen and nature of oxides Almost all metals combine with oxygen to form metal oxides. Write balanced chemical equations for the reaction of common metals like, and Aluminum with oxygen. What are such reactions called? Sodium Calcium Magnesium Aluminum Lead Silver Gold Catch fire easily. Covered with a thin layer of oxide at ordinary temperatures. Does not burn on heating but iron filings burn vigorously when sprinkled in the flame of a burner. Does not burn but hot metal is coated with black colored copper oxide. Do no react at all.
2 Most metal oxides are insoluble in water. However oxides of some metals like Potassium and Sodium dissolve in water to form alkalis. Write the balanced chemical equations for the reactions. What will be the result if a metal oxide reacts with an acid? What are such types of reactions called? (Hint: Metal oxides are basic in nature) What is an amphoteric oxide? Which oxides are amphoteric in nature? Write the balance chemical equation for the reaction of an amphoteric oxide with an acid and a base. Reaction with water Some metals react with water to produce metal oxide and hydrogen gas. Based on your current knowledge classify the following metals based on their reactivity with water sodium, potassium, calcium, aluminum, zinc, iron, copper and gold. Highly reactive (react with cold water) React with hot water React only with steam Do not react with water Write the balanced chemical equation for the reaction of sodium, aluminum and iron with water. What is the type of the chemical reaction?
3 Reaction with acids Activity Collect samples of commonly used metals like iron, copper, zinc, tin, lead, aluminum etc. Clean the samples with sand paper to remove any oxide layer that might have been formed on the surface. Put the samples in separate test tubes. Add dilute hydrochloric acid to each test tube. If required heat the test tube. Observe the rate of formation of bubbles of hydrogen gas carefully. Arrange the metals in descending order of reactivity with dilute hydrochloric acid. Do all metals react with acid? Reaction with other metal salts Activity Study the reactions of zinc, iron and copper in solutions of their salts, and to work out a reactivity series for them. Take small quantity of copper filings, iron filings and zinc granules in 3 test tubes. Add about 5 ml of copper sulphate solution to each test tube. Observe the color of the solution after about 5 minutes. Repeat the experiment above with zinc sulphate and ferrous sulphate solutions. Note down your observations in the table below sulphate Ferrous sulphate sulphate Write the balanced chemical equations for the reactions above. What are such reactions called?
4 More reactive metals displace less reactive metals from their metallic salts. Based on your experiment above, arrange copper, iron and zinc in the order of their reactivity. Reactivity series Based on the reactions of metals with oxygen, water, acids and other metallic salts, arrange the following metals in order of decreasing reactivity potassium, sodium, gold, iron, copper, zinc, silver, lead, aluminum, calcium, magnesium, hydrogen. Justify your answer. Please Send Camels, Monkeys and Colorful Zebras In Large & Heavy Containers with Many Security Guards. Extraction of metals from their ores Main steps Different methods used Concentration of the ore (removal of unwanted metals and gangue to purify the ore). Conversion to metal oxide. Reduction of metal oxide to metal. Refining of impure metal pure metals. into Hydraulic washing. Gravity separation. Froth floatation. Magnetic separation. Chemical separation. Calcination for carbonate ore. Roasting for sulphide ore. Roasting for metals low in the reactivity series. Reduction using more reactive element like carbon or aluminum. Electrolytic reduction for highly reactive elements, such as sodium and mercury, are obtained by electrolytic reduction when the metal is deposited at cathode. Electrolytic refining for copper, gold, tin, lead, chromium, nickel, etc. Liquation process for tin, lead and bismuth. Distillation process for zinc, mercury. Oxidation process for iron.
5 Complete the following table Name of ore Metal Chemical formula Method of extraction Bauxite Cuprite Hematite Magnetite Pyrite Pyrite Limestone Calamine Fluorspar Cryolite Common salt Flame test A flame test is a procedure used in chemistry to detect the presence of certain metal ions, based on each element's characteristic emission spectrum. The test involves introducing a sample of the element or compound to a hot, non-luminous flame, and observing the color that results. Samples are usually held on a platinum wire cleaned repeatedly with hydrochloric acid to remove traces of previous tests. Common metals and corresponding colors Metal Sodium Barium Calcium Magnesium Manganese Potassium Lithium Lead Color Intense Yellow Apple green Brick red Blue-Green Golden Bright white Bluish green Yellowish green Violet Red Blue/white