An electrolyte is a substance that when dissolved in a solution breaks up into ions. More specifically, an electrolyte breaks up into cations (positively charged ions) and anions (negatively charged ions). While strong electrolytes break up 100% into anions and cations, weak electrolytes break apart significantly less. Less than 10% of a weak electrolyte ionizes at all in solution. That means the 90%–99% of the weak electrolyte's molecules do not ionize. This is because the intermolecular forces that form between the solution and the weak electrolyte's molecules are not stronger than the intramolecular forces holding the molecule together. While solutions containing weak electrolytes contain both ions formed from the weak electrolyte ions and molecules of the weak electrolyte, they contain mostly molecules of the weak electrolyte.