Metallic Elements and Alloys

  • Metals and non-metals have distinct physical properties (Table 14.1).

  • Reactions with Water

    • Alkali metals (Group I) react with cold water forming hydrogen and metal hydroxide.
    • Reactivity increases down the group.
    • General equation: metal + water \rightarrow metal hydroxide + hydrogen

  • Reactions with Dilute Acids

    • Metals react to form salt and hydrogen; reactivity: Mg > Zn > Fe > H > Cu, Ag, Au

  • Alloys

    • Mixture of elements, usually metals, that are designed for particular properties (e.g., solder, bronze, brass, steel, stainless steel)
    • Metallic bonding still exists in metallic lattices in Alloys.
    • Alloy structures are frequently less regular and harder than pure metals as the layers cannot slide over one another easily as in pure metal.

  • Preventing Rusting (Corrosion requires both oxygen and water)

    • Barrier Methods: Painting, oiling/greasing, plastic coatings prevent contact with O2 and H2O
    • Galvanising: Coating with zinc - more effective since Zinc corrodes in preference and thus protects the underlying metal even if scratches are present in the zinc layer. Zinc is more reactive.
    • Sacrificial Protection: Attaching a more reactive metal block like Mg or Zn to the iron/steel hull. This more reactive metal corrodes in preference to Fe, avoiding rust.

  • General points on how metal can stop from rusting is the fact that oxidation occurs when they are not present with oxygen and water.. Also other factors like applying a certain material can avoid