Comprehensive Notes on Metals and Alloys

Metals

General Properties of Metals

  • Metals constitute the majority of elements in the periodic table.
  • Metals are located on the left side of the periodic table.
  • Examples include elements in Group 1A (e.g., Lithium, Sodium, Potassium), Group 2A (e.g., Beryllium, Magnesium, Calcium) and transition metals (e.g, Iron, Copper, Silver).
  • Metals are typically lustrous, malleable, ductile, and sonorous.
  • Metals form positive ions and react with oxygen to form oxides that are bases.

Metallic Bonding

  • Atoms are packed tightly in a regular lattice arrangement.
  • Metal ions exist in a "sea of electrons," where electrons are free to move.
  • Metallic bond: the attraction between metal ions and these free (delocalized) electrons.

Physical Properties and the Metallic Bond

  • Electrical Conductivity: Free electrons can carry electric charge.
  • High Melting and Boiling Points: Strong attractions exist between metal ions and the sea of electrons.
  • Malleability: Metals can be hammered into different shapes due to the ability of layers to slide over each other facilitated by the mobile electrons.
  • Ductility: Metals can be drawn out to make wires, also due to the ability of layers to slide.
  • Luster: Metals are lustrous due to the way they interact with light.
  • Sonorous: Metals make a ringing sound when struck.

Chemical Properties of Metals

  • Metals form positive ions (cations).
  • Metals react with oxygen to form oxides that are basic.

Alloys

  • Alloy: A mixture of metals, sometimes including non-metals (e.g., steel).
  • Metals are mixed in molten form.
  • Alloying changes the properties of the metal, making it more useful.
Why Alloys Have Different Properties
  • Introducing new atoms into the lattice hinders the layers from sliding easily.
  • Alloys are generally stronger than the original metal.
  • Alloys can be more resistant to corrosion.
Examples of Alloys
  • Brass: 70% copper and 30% zinc; harder than copper and does not corrode easily. Used in musical instruments, door knobs, and fittings.
  • Steel: An alloy of iron and carbon.

Reactivity Series

  • A more reactive metal will displace a less reactive metal from a compound (displacement reaction).
  • Example: Copper + silver nitrate → silver + copper nitrate
  • Silver + copper nitrate → no reaction
Mnemonic Device for the Reactivity Series
  • Please (Potassium)
  • Stop (Sodium)
  • Calling (Calcium)
  • Me (Magnesium)
  • A (Aluminium)
  • Careless (Carbon)
  • Zebra (Zinc)
  • Instead (Iron)
  • Try (Tin)
  • Learning (Lead)
  • How (Hydrogen)
  • Copper (Copper)
  • Saves (Silver)
  • Gold (Gold)
Special Case: Aluminum
  • Aluminum is very reactive and quickly forms a layer of aluminum oxide (Al<em>2O</em>3Al<em>2O</em>3) on its surface.
  • This oxide layer prevents further reaction of the aluminum underneath.
General Chemical Reactions of Metals
  • Metal + Acid → Salt + Hydrogen
  • Metal + Oxygen → Metal Oxide
  • Reactive Metal + Water → Metal Hydroxide + Hydrogen
Reactivity Series and Extraction of Metals
  • Metals lower in the reactivity series than carbon can be extracted from their oxides using carbon.
  • 2CuO(s)+C(s)→2Cu(s)+CO2(g)2CuO (s) + C (s) \rightarrow 2Cu (s) + CO_2 (g)
  • ZnO(s)+C(s)→Zn(s)+CO(s)ZnO (s) + C (s) \rightarrow Zn (s) + CO (s)
Examples of Chemical Reactions
  • 2Na (s) + 2 H2O (l) → 2NaOH (aq) + H2 (g)
  • Mg (s) + H2O (l) → MgO (s) + H2 (g)
  • Zn (s) + 2HCl (aq) → ZnCl2 (aq) + H2 (g)