Physical Properties: Metals vs Non-metals
| Property | Metals | Non-metals |
|---|---|---|
| Physical State | Solids at room temperature (Exception: Mercury $Hg$ is liquid) | Solids, liquids (Bromine $Br_2$), gases |
| Malleability | Highly malleable (beaten into thin sheets; Gold $Au$ & Silver $Ag$ most malleable) | Non-malleable, brittle (shatter under pressure) |
| Ductility | Highly ductile (drawn into fine wires; $1\text{ g}$ gold can yield $2\text{ km}$ wire) | Non-ductile |
| Thermal & Electrical Conductivity | Excellent conductors (Best: $Ag$, $Cu$; Poorest: $Pb$, $Hg$) | Poor insulators (Exception: Graphite allotrope of carbon conducts electricity) |
| Lustre & Sonority | Possess metallic lustre; produce ringing sound when struck | Dull (Exception: Iodine $I_2$ is lustrous); non-sonorous |
Chemical Properties & Reactivity Series
The Reactivity Series arranges metals in descending order of their chemical reactivity:
K > Na > Ca > Mg > Al > Zn > Fe > Pb > [H] > Cu > Hg > Ag > Au
<--- Most Reactive (Violent) Least Reactive (Inert) --->- Reaction with Oxygen: Metals form basic or amphoteric oxides.
- Amphoteric Oxides: React with both acids and bases to yield salt and water ($Al_2O_3$ and $ZnO$):
$$Al_2O_3 + 6HCl \rightarrow 2AlCl_3 + 3H_2O$$
$$Al_2O_3 + 2NaOH \rightarrow 2NaAlO_2\text{ [Sodium Aluminate]} + H_2O$$
- Reaction with Water:
- Sodium & Potassium: React violently with cold water, evolved $H_2$ catches fire instantly:
$$2Na(s) + 2H_2O(l) \rightarrow 2NaOH(aq) + H_2(g) + \text{Heat}$$
- Magnesium: Reacts with hot water to form $Mg(OH)_2$.
- Aluminum, Iron, Zinc: React only with steam ($H_2O(g)$).
- Copper, Silver, Gold: Do not react even with steam.
Ionic Compounds & Their Properties
An ionic bond is formed by the complete electrostatic transfer of one or more valence electrons from a metal atom to a non-metal atom.
Electron Dot Structure of Sodium Chloride ($NaCl$):
- $Na (2,8,1) \rightarrow Na^+ (2,8) + e^-$
- $Cl (2,8,7) + e^- \rightarrow Cl^- (2,8,8)$
- $Na^+ + Cl^- \rightarrow [Na^+][: \ddot{Cl} :-]$
Characteristic Properties of Ionic Compounds:
- High Melting & Boiling Points: Enormous electrostatic attractive forces between oppositely charged ions require tremendous thermal energy to overcome.
- Brittleness & Hardness: Solid and hard due to crystalline lattice; brittle because mechanical stress shifts layers of like charges together, producing repulsive cleavage.
- Electrical Conductivity: Do not conduct electricity in solid state (ions immobilized in rigid lattice); conduct efficiently in molten state or aqueous solution.
Metallurgy: Extraction of Metals
1. Concentration / Enrichment of Ore:
Removal of rocky impurities called gangue via hydraulic washing, froth floatation, or magnetic separation.
2. Conversion of Carbonate/Sulfide Ores to Oxides:
| Roasting | Calcination |
|---|---|
| Heating sulfide ore in excess presence of oxygen below its melting point. | Heating carbonate or hydrated ore in limited supply of air/absence of oxygen. |
| $2ZnS(s) + 3O_2(g) \xrightarrow{\Delta} 2ZnO(s) + 2SO_2(g)\uparrow$ | $ZnCO_3(s) \xrightarrow{\Delta} ZnO(s) + CO_2(g)\uparrow$ |
3. Reduction of Metal Oxide to Metal:
- Using Carbon ($C$ / Coke): $ZnO + C \rightarrow Zn + CO$
- Thermite Reaction: Reduction with highly reactive aluminum powder generates molten iron used to weld railway tracks:
$$Fe_2O_3(s) + 2Al(s) \xrightarrow{\Delta} 2Fe(l) + Al_2O_3(s) + \text{Tremendous Heat}$$
4. Electrolytic Refining of Copper:
- Anode: Thick slab of impure copper.
- Cathode: Pure thin sheet of refined copper.
- Electrolyte: Acidified copper sulfate solution ($CuSO_4 + \text{dil. } H_2SO_4$).
- Reaction at Cathode: $Cu^{2+} + 2e^- \rightarrow Cu(s)$ (Deposited).
- Reaction at Anode: $Cu(s) \rightarrow Cu^{2+} + 2e^-$ (Dissolved).
- Insoluble impurities settle beneath anode as anode mud (contains precious metals $Au, Ag, Pt$).
