Constitutional isomerism refers to a type of isomerism where compounds have the same molecular formula but differ in the connectivity of their atoms. This means that the atoms are arranged in different ways, leading to distinct chemical structures and properties. For example, C4H10 can exist as both butane and isobutane, which have different arrangements of carbon and hydrogen atoms. These variations in structure can result in different physical and chemical properties, such as boiling points and reactivity. Understanding constitutional isomerism is essential in fields like organic chemistry, as it helps chemists predict how different compounds will behave in reactions and their potential applications.