1.1.4 Half Equations & Ionic Equations

Half Equations

In a half equation:

• Oxidation is the loss of electrons.
• Reduction is the gain of electrons. Example of Oxidation:

When sodium (Na) loses an electron to form a sodium ion (Na⁺): $\text{Na} \rightarrow \text{Na}^+ + e^-$

Example of Reduction:

When chlorine (Cl₂) gains electrons to form chloride ions (Cl⁻): $\text{Cl}_2 + 2e^- \rightarrow 2\text{Cl}^-$

Balancing Half Equations:

• It is important to ensure that the number of electrons lost in the oxidation half equation equals the number of electrons gained in the reduction half equation.
• This allows for the correct combination of half equations to form a full ionic equation.

---

Ionic Equations