Zambia Grade 12 School Syllabus - Chemistry

Unit 1: Metals

• Topic 1.1: What is a Metal?
• Metals are elements that conduct electricity and heat effectively, readily forming cations with non-metals. They are located on the left side of the periodic table.
• Physical Properties: High densities, high melting/boiling points (due to strong atomic bonds), good conductors of heat and electricity (due to mobile electrons), high tensile strength, malleable (layers of atoms can slip past each other), and ductile.
• Structure: Arranged in rows, similar to ionic compounds. Outer electrons are easily lost, creating a "sea of electrons" around positive ions.
• Topic 1.2: Chemical Properties of Metals
• Reactivity varies, with more reactive metals displacing less reactive ones in displacement reactions.
• Reactions with Water: Produce hydrogen gas and a metal hydroxide. Aluminum appears unreactive due to a protective oxide layer.
• Reactions with Acid: Produce hydrogen gas and a salt, emitting heat (exothermic reaction).
• Reactivity Series: Ranks metals from most to least reactive (potassium, sodium, calcium, magnesium, zinc, iron, lead, copper, silver, gold).
• Reaction with Oxygen/Air: Form metal oxides.
• Decomposition of Metal Compounds: Nitrates, carbonates, and hydroxides decompose when heated, with varying products depending on the metal's reactivity.
• Topic 1.3: Extraction of Metals
• Metals are extracted from ores. Common methods include electrolysis (aluminum, sodium), roasting in air (copper, zinc), and heating with carbon (iron, zinc).
• Copper Extraction: Chalcopyrite is heated with sand and air, then further heated to produce blister copper. Electrolysis refines it further.
• Iron Extraction: Hematite and magnetite are heated with coke and limestone in a blast furnace. Limestone decomposes, forming slag that removes impurities. Coke reacts with oxygen, producing carbon monoxide, which reduces iron oxide to iron.
• Zinc Extraction: Zinc blende is roasted in air to form zinc oxide, then heated with coke to produce zinc. Electrolysis of zinc sulfate is another method.
• Aluminum Extraction: Bauxite is purified to aluminum oxide, then dissolved in molten cryolite and electrolyzed.
• Topic 1.4: Alloys
• Alloys are mixtures of two or more metals, formed by mixing molten metals.
• Steel Alloys: Steel, an iron-carbon alloy, has various types (cast iron, high carbon steel, medium carbon steel, low carbon steel) with different carbon percentages and uses. Alloy steels are made by mixing steel with other metals (chromium, cobalt, molybdenum, vanadium, tungsten) for specific properties.
• Mixing metals with different sized atoms increases strength.
• Topic 1.5: Corrosion of Metals
• Corrosion is the chemical attack of metals by oxygen, water, or other substances. Rusting is corrosion specific to iron and steel.
• Rusting requires both air (oxygen) and water.
• Prevention: Painting, oiling, galvanizing, tin plating, and electroplating.

Unit 2: Non-Metals

• Topic 2.1: Non-Metals: Key Points
• Non-metals have low melting/boiling points, poor conductivity, and low densities. They form negative ions with metals and covalent compounds with each other.
• Hydrogen: Prepared by reacting a reactive metal with acid. Lighter than air, explodes when mixed with oxygen and ignited. Manufactured from natural gas and water. Used in ammonia production, filling balloons, and as fuel.
• Oxygen: Colorless, odorless, slightly soluble in water. Manufactured by fractional distillation of air. Used in welding, as a chemical reagent, and for respiration. Ozone (O3) is a protective layer in the upper atmosphere.
• Water: Oxide of hydrogen. Turns white copper sulfate blue.
• Nitrogen: Makes up 80% of the atmosphere. Very unreactive. Manufactured by fractional distillation of liquid air. Used in refrigeration.
• Ammonia: Made by the Haber process (nitrogen and hydrogen at 200 atm and 450°C with an iron catalyst). Converted to nitrates for fertilizers. Pungent smell, dissolves in water to form ammonium hydroxide. Turns moist red litmus paper blue. Reacts with acids to form ammonium salts.
• Carbon: Exists as allotropes (diamond, graphite).
• Carbon Dioxide: Colorless, odorless, heavier than air, slightly soluble in water, turns moist blue litmus paper red, turns limewater milky. Used in soft drinks, dry ice, and photosynthesis.
• Limestone: Calcium carbonate. Used in cement, quicklime (calcium hydroxide), and slaked lime (calcium oxide).
• Carbon Monoxide: Colorless, odorless, poisonous, insoluble in water, neutral oxide. Used as a reducing agent in furnaces.
• Topic 2.2: What are Non-Metals?
• Elements on the right side of the periodic table. Low melting/boiling points, low densities, electrical insulators, brittle, poor heat conductors.
• Topic 2.3: Hydrogen
• Preparation: Reacting zinc with hydrochloric acid. Tested by burning splint with a "pop" sound.
• Industrial Preparation: From methane (heated with steam and nickel catalyst) or electrolysis of water.
• Topic 2.4: Oxygen
• Most common element in Earth's crust.
• Preparation: Heating potassium chlorate or decomposing hydrogen peroxide. Collected over water.
• Industrial Manufacture: Fractional distillation of air.
• Topic 2.5: Ammonia
• Haber Process: Nitrogen and hydrogen react at 200 atm and 450°C with an iron catalyst to produce ammonia.
• Topic 2.6: Carbon
• Allotropes: Diamond (jewelry, cutting tools) and graphite (pencils, electrodes, lubricant).
• Topic 2.7: Limestone and its Uses
• Composed of calcium carbonate. Used in cement, road building, glass making, and iron extraction.

Unit 3: Organic Chemistry

• Topic 3.1: Organic Chemistry: Key Points
• Organic chemistry studies carbon compounds in living things.
• Hydrocarbons: Organic compounds of hydrogen and carbon.
• Alkanes: Saturated hydrocarbons with single carbon-carbon bonds. General formula: CnH2n+2.
• Alkenes: Unsaturated hydrocarbons with at least one double carbon-carbon bond. Undergo addition reactions (with halogens, hydrogen, steam, hydrogen halides) and addition polymerization.
• Isomerism: Structural (branched chains) and positional (different double bond position).
• Alkane Production: Fractional distillation of crude oil. Used as fuels and chemical feedstocks.
• Alkene Production: Cracking alkanes using heat and a catalyst.
• Topic 3.2: Alkanes
• Found in crude oil. Saturated hydrocarbons. Homologous series with general formula CnH2n+2.
• Topic 3.3: Isomers: Branched Chain Alkanes
• Isomers have the same molecular formula but different structural formulas. Branched chain isomers have lower melting points.
• Topic 3.4: Making Alkanes
• Fractional distillation of crude oil separates fractions based on boiling points.
• Topic 3.5: Chemical Behaviour of Alkanes
• Relatively unreactive. Burn easily. Undergo substitution reactions with halogens (e.g., chlorine).
• Topic 3.6: Alkenes
• Homologous series with general formula CnH2n. More reactive than alkanes due to double bond. Used in plastics and alcohol production.
• Topic 3.7: Chemical Behaviour of Alkenes
• Burn with a yellowish flame. React with bromine water (turns colorless), potassium permanganate (turns colorless).
• Topic 3.8: Addition Reactions
• Hydrogenation: Adding hydrogen across the double bond (e.g., ethene to ethane). Used in margarine production.
• Hydration: Adding water (steam) across the double bond (e.g., ethene to ethanol).
• Halogenation: Adding halogens across the double bond (e.g., bromine to ethene). Test for unsaturation.
• Polymerization: Joining many alkene molecules to form a long chain (e.g., ethene to polyethene).
• Topic 3.10: Alcohols, Carboxylic Acids, Esters: Key Points
• Alcohols: Contain a hydroxyl group (-OH). General formula: CnH2n+1OH. Made from alkenes or ester hydrolysis. Ethanol is a fuel, solvent, and disinfectant.
• Carboxylic Acids: Contain -COOH group. Weak acids. React with metals, carbonates, and alkalis. Made by oxidizing alcohols. React with alcohols to form esters.
• Esters: Made by reacting carboxylic acids with alcohols. Sweet smells. Hydrolyzed to form carboxylic acids and alcohols. Found in fats and oils.
• Topic 3.11: Alcohols
• Homologous series with general formula CnH2n+1OH.
• Topic 3.12: Properties of Alcohols
• High boiling points, low volatility, polar. Ethanol is a common alcohol.
• Topic 3.13: Carboxylic Acids
• Homologous series with general formula CnH2n+1COOH. Strong smells. Ethanoic acid (acetic acid) is found in vinegar.
• Topic 3.14: Esters
• Strong, pleasant smells. Found in fruits and flowers. Named after the acid and alcohol they are derived from.

Unit 4: Macromolecules

• Topic 4.1: Macromolecules: Key Points
• Large molecules with long carbon chains. Natural (proteins, carbohydrates, fats) and synthetic (plastics, fibers).
• Synthetic Macromolecules: Polymers made from monomers. Addition polymers (polyethene, PVC, polypropylene) and condensation polymers (nylon, terylene).
• Thermoplastic polymers soften on heating, thermosetting polymers do not.
• Natural Macromolecules: Proteins (amino acid monomers linked by amide bonds), carbohydrates (glucose polymers linked by glycosidic bonds), fats (esters of fatty acids and glycerol).
• Hydrolysis breaks down macromolecules. Saponification is the hydrolysis of fats to make soap.
• Topic 4.2: Synthetic Polymers
• Addition Polymers: Formed by addition reactions (e.g., polyethene from ethene).
• Condensation Polymers: Formed by reactions between two different monomers, eliminating water (e.g., nylon, terylene).
• Topic 4.3: Natural Macromolecules
• Proteins: Polyamides made from amino acids linked by peptide bonds.
• Carbohydrates: Polymers of glucose.
• Fats and Oils (Lipids): Esters of glycerol and fatty acids.
• Soap Making: Saponification (hydrolysis of fats) to produce fatty acids, which react to form soap salts.

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