Covalent bond a chemical bond in which one or more pairs of electrons are Shared between two atoms.

任何由两个氧原子以单个共价键相互结合在一起的一类化合物。

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So, in talking about covalent bonds, we should be able to still apply a more general definition of a chemical bond, which should tell us that the h 2 molecule is going to be lower in energy than if we looked at 2 separate hydrogen atom molecules.

那么，既然提到了共价键，我们应该还可以,给化学键下一个更普遍的定义,那就是告诉我们氢分子能量应该更低,与两个分开的氢的单原子分子相比。

麻省理工公开课 - 化学原理课程节选