Reactivity Series

What is the reactivity series of metals?

• The study of metal chemistry involves analyzing their reactions with water and acids.
• Observing these reactions allows for the creation of a reactivity series that orders metals based on their reactivity levels.
• This series is useful for arranging metals in terms of reactivity by observing their reactions with water and acids.
• Hydrogen and carbon, despite being non-metals, are part of the reactivity series due to their role in extracting metals from their oxides.
• The reactivity series includes non-metals like hydrogen and carbon, essential for metal extraction from oxides.

Reactivity Series of Metals 

How to remember the reactivity series

• Observations from the table above allow us to deduce the reactivity series.
• We can memorize the order of the reactivity series with the mnemonic: "Please send cats, monkeys and cute zebras into hot countries signed Gordon."

Reactions of Metals

Reaction with cold water

• The more reactive metals will react with cold water to produce a metal hydroxide along with hydrogen gas.
• Examples include potassium, sodium, and calcium, as they are highly reactive and undergo reactions with cold water.
  Metal + Water → Metal Hydroxide + Hydrogen
• Calcium and Potassium Reactions:
  Ca (s) + 2H₂O (l) → Ca(OH)₂ (aq) + H₂ (g)
  K (s) + H₂O (l) → KOH (aq) + H₂ (g)

Reacting with Steam

• Metals below calcium in the reactivity series, like magnesium, react with steam to form a metal oxide and hydrogen gas:
  Mg (s) + H₂O (g) → MgO (s) + H₂ (g)

Reaction with dilute acids

• Metal Reactivity with Acids: Only metals above hydrogen in the reactivity series will react with dilute acids.
• Unreactive Metals: Metals like gold, silver, and copper, which are below hydrogen, do not react with acids.
• Reactivity Levels: The more reactive the metal, the more vigorous the reaction.
• High Reactivity Metals: Metals high in the reactivity series, such as potassium and sodium, react explosively with acids.
• Acid-Metal Reactions: When acids react with metals, they produce a salt and hydrogen gas: metal + acid → salt + hydrogen
• Some examples of metal-acid reactions and their equations are given below:
  

Reaction with oxygen

• Reactive metals like alkali metals easily react with oxygen.
• Silver, copper, and iron can also react with oxygen, albeit at a slower rate.
• Upon reacting with oxygen, metals form metal oxides. For instance, copper reacts as follows:
  metal + oxygen → metal oxide
  2Cu (s) + O₂ (g) → 2CuO (s)
• Gold, however, does not react with oxygen.

The Order of Reactivity of Metals

• The reactivity series of metals can be determined through experimental observations of their reactions with water, acids, and oxygen.
• A metal's position in the reactivity series correlates with the intensity of its reaction - more vigorous reactions signify higher positions in the series.
• For highly reactive metals, their reactivity order can be established by observing their reactions with water.
• Less reactive metals either react slowly or not at all with water, necessitating the observation of their reactions with dilute acid to determine their reactivity order.
• Changes in temperature during a reaction can also indicate the order of reactivity; a significant temperature change suggests higher reactivity.

Examples:

• Sodium (Na) and Water: Sodium reacts vigorously with water, producing hydrogen gas and a strong alkaline solution of sodium hydroxide. This reaction indicates sodium's high reactivity.
• Gold (Au) and Water: Gold, being a noble metal, does not react with water under normal conditions, showcasing its low reactivity.