pentamethylene

例句：

1. 1. This compound is made from five different elements.
   这种化合物由五种不同的元素组成。
2. 2. The molecule has a structure with five carbon atoms and five hydrogen atoms.
   这个分子的结构有五个碳原子和五个氢原子。
3. 3. The molecule is stable at room temperature due to its high molecular weight.
   由于分子量大，该分子在室温下是稳定的。