Nimo

Study smarter with Nimo

Personalised revision that adapts to you. Ace your revision with unlimited practice questions that are designed to help you learn faster. We're slowly rolling out to more and more students.

Try Nimo

Write balanced half-equations and ionic equations

Atomic structure and the periodic table • Atomic models and isotopes

Key concepts

What you'll likely be quizzed about

  • A half-equation represents the oxidation or reduction of a single reactant or product, explicitly indicating electrons lost or gained.
  • Electrons appear on one side of the arrow to ensure charge balance, and both charge and atom balance dictate the required number of electrons.

Flashcards

Test your knowledge with interactive flashcards

Where are electrons placed in an oxidation half-equation?

Click to reveal answer

In an oxidation half-equation, electrons are placed on the right-hand side.

Key notes

Important points to keep in mind

Balance atoms other than H and O first.

Use H2O to add oxygen atoms and H+ to add hydrogen atoms in acidic conditions.

Add electrons last to balance overall charge.

In alkaline conditions, convert H+ to H2O using OH- and cancel H2O.

Split only soluble ionic species when writing full ionic equations.

Cancel spectator ions to produce the net ionic equation.

Check both mass and charge balance for every equation.

Multiply half-equations to equalize electrons before combining.

Keep insoluble solids and gases as molecules in ionic equations.

Common half-equation templates can speed up balancing frequent redox pairs.

Built with v0