Metals are elements that are generally lustrous, good conductors of heat and electricity, malleable and ductile, and usually solid at room temperature (except mercury).
Non-metals are elements that are not lustrous, are poor conductors of heat and electricity (except graphite), and are brittle when solid. They may be gases, liquids (e.g., bromine) or solids.
Shiny (lustre), malleable, ductile, good conductors of heat and electricity, high density (mostly), usually solid at room temperature.
Dull (not shiny), brittle if solid, poor conductors of heat and electricity (graphite is an exception), low density in many cases; may exist as gases or liquids.
Metals have delocalised (free) electrons in a lattice of positive ions; these electrons move under an electric field, allowing conduction.
The reactivity series is an order of metals from most reactive to least reactive (e.g., K, Na, Ca, Mg, Al, Zn, Fe, Pb, Cu, Ag, Au). It predicts displacement reactions and extraction difficulty.
Metals form metal oxides. Reactive metals form basic oxides (e.g., 2Mg + O2 → 2MgO) and sometimes metal peroxides for very reactive metals.
Non-metals form covalent oxides. Example: C + O2 → CO2; sulphur forms SO2 or SO3. These oxides can be acidic.
A more reactive metal displaces a less reactive metal from its salt solution. Example: Zn + CuSO4 → ZnSO4 + Cu.
Native metals occur in nature in metallic form (not combined). Examples: gold (Au), silver (Ag), and sometimes copper (Cu).
An ore is a naturally occurring rock that contains sufficient minerals of a metal to make extraction economically feasible. Examples: hematite (Fe2O3), bauxite (Al2O3·xH2O), malachite (CuCO3·Cu(OH)2).
Concentration removes impurities (gangue) from ore. Methods include gravity separation, magnetic separation, and froth flotation depending on ore type.
Roasting involves heating sulfide ores in presence of oxygen to convert to oxides (e.g., 2ZnS + 3O2 → 2ZnO + 2SO2). Calcination heats carbonate ores in limited air to remove CO2 (e.g., CaCO3 → CaO + CO2).
Metals are reduced from oxides using reducing agents (carbon, CO, H2) or by electrolytic reduction. For reactive metals (like Al), electrolytic reduction is used (Hall–Héroult process).
Bauxite is purified by the Bayer process to get alumina (Al2O3), then alumina is electrolysed (Hall–Héroult) in molten cryolite to obtain aluminium metal.
Hematite (Fe2O3) is reduced by CO in a blast furnace producing molten iron. Limestone acts as flux to remove impurities as slag.
Refining methods include electrolytic refining (e.g., copper), distillation (e.g., zinc), liquation, zone refining and chemical methods depending on metal and impurities.
An alloy is a mixture of two or more elements (one usually metal) to improve properties. Examples: steel (Fe + C) is strong and used in construction; brass (Cu + Zn) used in musical instruments; bronze (Cu + Sn) used for statues.
Corrosion is the deterioration of metals due to chemical reactions with the environment (e.g., rusting of iron due to O2 and moisture; acid rain accelerates corrosion).
Methods: painting, oiling/greasing, galvanisation (zinc coating), electroplating, making alloys (stainless steel), sacrificial protection (using more reactive metals).
Sacrificial protection uses a more reactive metal (e.g., zinc) connected to iron; the reactive metal corrodes preferentially, protecting the iron (used in cathodic protection).
Electroplating deposits a metal coating on an object using electrolysis (e.g., silver plating of cutlery) for protection, decoration, or conductivity.
Very reactive metals (e.g., K, Na) react violently with water producing hydroxide and hydrogen (2Na + 2H2O → 2NaOH + H2↑). Less reactive metals like iron react slowly (rusting involves water and oxygen rather than direct reaction).
Many metals react with dilute acids to produce a salt and hydrogen gas. Example: Zn + 2HCl → ZnCl2 + H2↑.
Copper is below hydrogen in the reactivity series, so it cannot displace hydrogen from dilute acids; thus no reaction occurs with dilute HCl.
Gold and silver are less reactive; they do not oxidise easily and thus occur in native form or resist tarnishing (though silver tarnishes slowly as Ag2S).
Zone refining purifies metals by melting a small region (zone) and moving impurities along the bar to one end. Widely used for semiconductors and high-purity metals.
Passivation is forming a protective oxide layer on a metal surface (e.g., chromium oxide on stainless steel) that prevents further corrosion.
Amphoteric oxides react with both acids and bases. Example: Al2O3 reacts with HCl and with NaOH.
Stainless steel is an alloy of iron with chromium (and often nickel); chromium forms a protective chromium oxide layer that prevents rusting.
Metals show metallic bonding with delocalised electrons. Non-metals typically form covalent bonds (sharing electrons) or ionic bonds when reacting with metals.
With oxygen: form oxides. With water: produce hydroxides and H2 (if reactive). With acids: produce salt and H2. Less reactive metals may not react readily.
Metals below carbon in reactivity series (e.g., Fe, Zn, Pb) can be reduced from their oxides using carbon (coke) as reducing agent in furnaces because carbon is a stronger reducing agent than these metals.
Aluminium is light, corrosion-resistant and a good conductor; used in aircraft, packaging (foils), utensils, electrical cables and construction.
Copper is an excellent conductor of electricity, ductile and relatively resistant to corrosion, making it ideal for electrical wiring and motors.
Lead is used in storage batteries, radiation shields and pipes historically. Lead is toxic and can cause health problems; its use is reduced in many applications.
Graphite has free electrons within its layers (delocalised electrons) allowing electrical conduction along planes; it is used in electrodes and lubricants.
Non-metals gain electrons to form anions when reacting with metals (ionic compounds). With oxygen they form acidic oxides; with other non-metals they form covalent compounds.
When two soluble salts react to form an insoluble salt (precipitate), e.g., AgNO3 + NaCl → AgCl↓ + NaNO3.
Bring a burning splint near the gas — it gives a characteristic 'pop' sound indicating hydrogen gas.
Stainless steel is primarily iron with 10–20% chromium and often nickel; chromium forms a passive oxide layer, making it corrosion-resistant — used in cutlery, surgical instruments and construction.
Test conductivity: metals conduct electricity when solid; non-metals generally do not (graphite is exception). Also metals are malleable; non-metals brittle.
Flux (e.g., limestone) combines with impurities to form slag which is removed. It helps purify the metal during smelting.
Impacts include habitat destruction, air and water pollution (acid mine drainage, SO2 emission), energy consumption and waste (tailings). Sustainable practices and recycling mitigate effects.
Recycling conserves natural resources, reduces energy use and pollution, and decreases mining waste. Metals like aluminium and steel are highly recyclable.
Wear goggles and gloves, handle hot metals with tongs, avoid inhaling fumes (use fume hood), do not mix incompatible chemicals, and neutralise acid/alkali spills safely.
Examples to balance: (1) Fe + O2 → Fe2O3 (2) Zn + HCl → ZnCl2 + H2 (3) 2K + Cl2 → 2KCl. Practice balancing atom counts for each element.
Ore samples are often dense, coloured (due to metal ions), and may yield characteristic reactions (e.g., addition of acid producing CO2 for carbonates). Physical properties and tests combined with microscopy help identification.
Remember definitions, properties, reactivity series, common reactions (with O2, water, acids), extraction steps for Al and Fe, corrosion & prevention, and common alloys + their uses.
- Create short mnemonics for reactivity series (e.g., "Please Stop Calling Me A Zebra Instead Try Learning Calmly" for an order).
- Make flashcards for ores, alloys and extraction steps.
- Practice balancing and writing reactions every day for accuracy.
- Use diagrams for blast furnace and electrolytic cells to visualise processes.
NCERT Class 10 — Chapter: Metals & Non-metals