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

Metal + Oxygen Reactions

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

Metal + Water Reactions (most reactive metals)

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

Displacement Reactions (Higher)

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

Extraction with Carbon

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

Balancing Symbol Equations (Higher)

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

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 $\text{CuCl}_2$, starting temperature, mass of metal
• Higher tier details: use excess acid; warm $\text{H<em>2SO</em>4}$ to speed up formation of $\text{CuSO}_4$