Reactivity Series

Definition of the Reactivity Series

  • The Reactivity Series refers to a list of elements based on their reactivity, from most reactive to least reactive.
  • It is a tool used in chemistry to predict the outcomes of reactions.
  • Here, reactivity denotes the tendency of an element to undergo a chemical reaction.

Arrangement of Metals in the Reactivity Series

  • The Reactivity Series begins with the most reactive metals at the top: Potassium (K), Sodium (Na), Calcium (Ca), Magnesium (Mg), Aluminium (Al).
  • In the middle of the series, we find Zinc (Zn), Iron (Fe) and Lead (Pb).
  • Lastly, the least reactive metals are Copper (Cu), Silver (Ag), Gold (Au), and Platinum (Pt) at the bottom.
  • Remember that the most reactive metals are at the top, while less reactive ones are at the bottom.

Observing Reactivity

  • Reactivity of metals can be observed in several ways such as their reaction with water, oxygen, or acids.
  • Highly reactive metals like potassium or sodium react violently with water. On the other hand, less reactive metals like iron or copper show little to no reaction.
  • Oxidation happens when metals react with oxygen. Highly reactive metals form an oxide layer quickly while less reactive metals form it slowly.
  • Reactions with acids show that more reactive metals tend to produce more hydrogen gas than less reactive metals.

Displacement Reactions

  • A displacement reaction occurs when a more reactive metal displaces a less reactive metal from its compound.
  • This is governed by the Reactivity Series. For example, if zinc (which is above iron in the sequence) is added to a solution of iron(II) sulphate, it will displace the iron.

Extraction of Metals

  • The Reactivity Series is crucial in extracting metals from their ores.
  • Metals higher in the series require more energy-intensive methods for extraction, typically through electrolysis.
  • Metals found lower in the series can often be extracted by reduction using a more reactive metal or carbon. For instance, copper can be extracted from its ore by heating with carbon, which is more reactive and therefore can displace the copper.
  • Metals tend to be more reactive than non-metals, and within the metals, alkali metals (found in Group 1 of the Periodic Table) are more reactive than transition metals.
  • Reactivity increases down the Group 1 alkali metals, hence lithium at the top is less reactive than potassium at the bottom.
  • Transition metals, found in the middle of the Periodic Table, are generally less reactive.

By understanding the Reactivity Series, predictions can be made about the outcome of chemical reactions, and safe and efficient procedures for extracting metals can be established.