Metals and Their Reactions – Quick Revision Notes

Periodic Table

  • Elements arranged in vertical groups and horizontal periods
  • Metals occupy the left & middle of the table

Properties of Metals

  • Shiny appearance
  • Good electrical & thermal conductors
  • High melting points & densities
  • Malleable (change shape when hammered)

Reactivity Series (most → least)

  • \text{K} > \text{Na} > \text{Ca} > \text{Mg} > \text{Al} > \text{Zn} > \text{Fe} > \text{Cu} > \text{Ag} > \text{Au}

Metal + Acid Reactions

  • General: acid+metal→salt+H2\text{acid} + \text{metal} \rightarrow \text{salt} + \mathrm{H_2}
  • Test for H2\mathrm{H_2}: lit splint → “squeaky pop”
  • Salt endings:
    • HCl⇒chloride\text{HCl} \Rightarrow \text{chloride}
    • H<em>2SO</em>4⇒sulfate\text{H<em>2SO</em>4} \Rightarrow \text{sulfate}
    • \text{HNO_3} \Rightarrow \text{nitrate}
  • Examples:
    • Mg+HCl→MgCl<em>2+H</em>2\text{Mg} + \text{HCl} \rightarrow \text{MgCl}<em>2 + \mathrm{H</em>2}
    • Zn+HNO<em>3→Zn(NO</em>3)<em>2+H</em>2\text{Zn} + \text{HNO}<em>3 \rightarrow \text{Zn(NO}</em>3)<em>2 + \mathrm{H</em>2}

Metal + Oxygen Reactions

  • General: metal+O2→metal oxide\text{metal} + \mathrm{O_2} \rightarrow \text{metal oxide}
  • Example: 2Mg+O2→2MgO2\text{Mg} + \mathrm{O_2} \rightarrow 2\text{MgO}

Metal + Water Reactions (most reactive metals)

  • General: metal+H<em>2O→metal hydroxide+H</em>2\text{metal} + \mathrm{H<em>2O} \rightarrow \text{metal hydroxide} + \mathrm{H</em>2}
  • Example: 2Na+2H<em>2O→2NaOH+H</em>22\text{Na} + 2\mathrm{H<em>2O} \rightarrow 2\text{NaOH} + \mathrm{H</em>2}
  • Metal hydroxide = alkali (universal indicator: blue/purple)

Displacement Reactions (Higher)

  • A more reactive metal displaces a less reactive metal from its compound
  • Example: CuSO<em>4+Zn→ZnSO</em>4+Cu\text{CuSO}<em>4 + \text{Zn} \rightarrow \text{ZnSO}</em>4 + \text{Cu}
  • No reaction if incoming metal is less reactive (e.g. MgSO4+Zn→no reaction\text{MgSO}_4 + \text{Zn} \rightarrow \text{no reaction})

Extraction with Carbon

  • Metals less reactive than carbon reduced from oxides by heating with carbon
  • Example: CuO+C→Cu+CO2\text{CuO} + \text{C} \rightarrow \text{Cu} + \text{CO}_2

Balancing Symbol Equations (Higher)

  • Add coefficients only; atoms on each side equal
  • \text{Unbalanced: Mg + O2 \rightarrow MgO} → 2Mg+O</em>2→2MgO2\text{Mg} + \mathrm{O</em>2} \rightarrow 2\text{MgO}
  • \text{Unbalanced: Zn + HCl \rightarrow ZnCl}2 + \mathrm{H2} → Zn+2HCl→ZnCl<em>2+H</em>2\text{Zn} + 2\text{HCl} \rightarrow \text{ZnCl}<em>2 + \mathrm{H</em>2}

Practical: Comparing Metal Reactivity (with CuCl₂ solution)

  • Independent variable: type of metal
  • Dependent variable: measured temperature rise / rate of reaction
  • Control variables: volume & concentration of CuCl2\text{CuCl}_2, starting temperature, mass of metal
  • Higher tier details: use excess acid; warm H<em>2SO</em>4\text{H<em>2SO</em>4} to speed up formation of CuSO4\text{CuSO}_4