Final answer:
Isomers are molecules that share the same chemical formula but differ in the arrangement of their atoms or chemical bonds.
Step-by-step explanation:
Isomers are molecules that share the same chemical formula but differ in the arrangement of their atoms or chemical bonds. They are common in organic chemistry and occur when three or more carbon atoms can bind in more than one order. For example, butane and isobutene are structural isomers with the molecular formula C4H10, but they have different arrangements of their carbon and hydrogen atoms, leading to differences in their chemical properties.