A net ionic equation is a simplified version of a chemical equation that shows only the species directly involved in a chemical reaction. It eliminates spectator ions, which are ions that do not change during the reaction. This helps to focus on the actual chemical changes taking place. To write a net ionic equation, start with a balanced molecular equation and then break down the soluble ionic compounds into their constituent ions. After identifying and removing the spectator ions, the remaining ions represent the net ionic equation, highlighting the essential components of the reaction.