GCSE Chemistry revision

Cells and batteries

Chemical cells and fuel cells (chemistry only)

AQA 4.5.2.1 Foundation & Higher

Your specification

AQA student objectives

Learning pathway

ALL 🎯

MOST 🎯🎯

SOME 🎯🎯🎯

Revision summary

Read on screen, then print for Cornell-style active revision.

Tendency to Form Positive Ions: A metal's reactivity is determined by how easily its atoms lose outer electrons to form positive ions (cations), with more reactive metals displacing less reactive metals from solutions of their aqueous ions.
Displacement Examples: In the series Mg > Zn > Fe > Cu > Ag, magnesium has the greatest tendency to form positive ions. Adding magnesium ribbon to copper(II) sulfate solution results in a displacement reaction where magnesium dissolves and copper metal coats the surface: Mg(s) + Cu²⁺(aq) → Mg²⁺(aq) + Cu(s)
Conversely, adding copper metal to silver nitrate solution displaces silver, but copper cannot displace iron or magnesium ions because copper is less reactive.

1. Relative Reactivity and Ion Formation via Displacement AQA

Tendency to Form Positive Ions: A metal's reactivity is determined by how easily its atoms lose outer electrons to form positive ions (cations), with more reactive metals displacing less reactive metals from solutions of their aqueous ions.
Displacement Examples: In the series Mg > Zn > Fe > Cu > Ag, magnesium has the greatest tendency to form positive ions. Adding magnesium ribbon to copper(II) sulfate solution results in a displacement reaction where magnesium dissolves and copper metal coats the surface: Mg(s) + Cu²⁺(aq) → Mg²⁺(aq) + Cu(s)
Conversely, adding copper metal to silver nitrate solution displaces silver, but copper cannot displace iron or magnesium ions because copper is less reactive.

Connecting two different metals in an electrolyte creates a chemical cell, where a greater difference in reactivity between the two metals generates a higher voltage output.
Example: A cell made with a Magnesium-Copper electrode pair produces a significantly higher voltage than an Iron-Copper pair because magnesium loses electrons far more readily than iron; however, cells must be evaluated practically based on voltage needs, material costs, and electrode corrosion over time.

2. Simple Cells AQA

Connecting two different metals in an electrolyte creates a chemical cell, where a greater difference in reactivity between the two metals generates a higher voltage output.
Example: A cell made with a Magnesium-Copper electrode pair produces a significantly higher voltage than an Iron-Copper pair because magnesium loses electrons far more readily than iron; however, cells must be evaluated practically based on voltage needs, material costs, and electrode corrosion over time.