1. Isomerism is the phenomenon of two or more chemical compounds having the same molecular formula but different structural arrangements.
同分异构性是指两个或更多化学化合物具有相同的分子式但结构排列不同的现象。

2. The presence of isomerism in organic compounds often leads to differences in their physical and chemical properties.
有机化合物中存在同分异构性往往导致其物理和化学性质的差异。