Let's try to dissolve an ionic substance in water, for example sodium chloride. The dipolar molecules of water exert such intense attractive forces on the solid that they tear the ions apart one after the other. Each ion is always surrounded by water molecules and is defined as hydrated. The overall process just described is a dissolution which is called ionic dissociation and can be represented with an equation. What happens if we dissolve substances composed of polar molecules in water? Let's try to put a molecular and polar substance such as sucrose in water. The dipolar molecules of water attract the sucrose molecules on the surface of the crystals with pole-to-pole attractive forces until they detach from the others and bring them all into solution. Each sucrose molecule is always surrounded by water molecules and is said to be a hydrated molecule. Sucrose has dissolved in water and its molecules have dispersed among those of the water. The overall process just described is a dissolution and can be represented with an equation. When we put particular molecules in water, we try to put particular molecules in water. Polar molecular compounds sometimes do not simply dissolve. But a real chemical reaction can occur. For example, when we put a molecular substance such as hydrogen chloride in water, its polar molecules react with the water. Each molecule of hydrogen chloride breaks, forming two hydrated ions. In this case, there are no more hydrogen chloride molecules in the solution. But positive and negative ions have formed, which give particular properties to the system. The overall process in which ions are formed from a molecule is a chemical transformation called an ionization reaction and can be represented with an equation.