Overview
This lecture covers the properties, reactions, and extraction of metals and non-metals, focusing on key chapter points, definitions, reactivity series, and corrosion, as per CBSE/ICSE/NCERT syllabus.
Classification of Matter
- Matter is divided into pure (elements and compounds) and impure substances.
- Elements are classified as metals, non-metals, and metalloids.
Metals and Non-Metals: Definitions & Properties
- Metals donate electrons, are electropositive, and conduct heat and electricity.
- Non-metals accept/gain electrons, are electronegative, and are poor conductors.
- Metals have 1-3 valence electrons; non-metals have 5-7.
- Metals are generally ductile, malleable, lustrous, dense, sonorous, and hard; non-metals are not.
- Exceptions: Graphite (non-metal, conducts electricity); Diamond (non-metal, hard & lustrous); Sodium/Potassium (soft metals); Gallium (low melting point).
- States: Metals are solids (except mercury); non-metals may be solid, liquid, or gas.
Chemical Properties
- Metals donate electrons forming positive ions (cations); non-metals accept electrons forming negative ions (anions).
- Metal oxides are basic; non-metal oxides are acidic.
- Amphoteric oxides (e.g., Al₂O₃) react with both acids and bases.
- Corrosion: Metals (like iron) react with air and moisture, forming rust.
Reactivity Series
- Reactivity series ranks elements by chemical reactivity (K > Na > Ca > Mg > Al > Zn > Fe > Pb > H > Cu > Ag > Au).
- More reactive metals displace less reactive metals from compounds.
- Top series (e.g., K, Na) are highly reactive with water and air.
Important Reactions
- Metal + Water: Highly reactive metals form hydroxides and H₂; less reactive metals form oxides.
- Metal + Oxygen: Forms metal oxides (basic or amphoteric).
- Metal + Acid: Forms salt and H₂ (except with HNO₃, which is a strong oxidizer).
- Metal + Non-metal: Forms ionic compounds (salts)—high melting/boiling points, soluble in water, conduct electricity when molten/aqueous.
Extraction of Metals
- Metallurgy: Science of extracting metals from ores.
- Minerals: Naturally occurring substances with metals.
- Ores: Minerals with high metal content, economically viable for extraction.
- Gangue: Impurities in ore.
- Ores are concentrated before extraction (removing gangue).
- Low reactivity metals: Extracted by roasting/calcination and reduction.
- Medium reactivity metals: Roasted/calcined, then reduced by carbon.
- Highly reactive metals: Extracted via electrolysis.
- Refining: Electrolytic process purifies metals (impurities form anode mud).
Corrosion and Prevention
- Rusting needs both air and water; prevented by painting, oiling, greasing, galvanization (zinc coating), chrome plating, anodizing (for aluminum), and alloying (e.g., making steel).
Key Terms & Definitions
- Metallurgy — science and technology of extracting and purifying metals.
- Mineral — naturally occurring substance with metals/compounds.
- Ore — mineral with high percentage of desired metal.
- Gangue — impurities in the ore.
- Ductility — ability to be drawn into wires.
- Malleability — ability to be hammered into sheets.
- Amphoteric Oxide — oxide reacting with both acids and bases (e.g., Al₂O₃).
- Anode Mud — impure residue from electrolytic refining.
Action Items / Next Steps
- Review and memorize the reactivity series and key exceptions.
- Download and solve the chapter-wise previous year question booklet.
- Complete the question practice booklet with assertion/reasoning/MCQs.
- Ensure understanding of extraction, corrosion, and prevention techniques.
- Write in comments: “This is going to be the best exam of my life.”