来自《耶鲁大学开放课程：新生有机化学 第2集 第2集》

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  it's half as strong as a carbon-carbon bond.
  键能相当于碳碳单键的一半
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  So what's the glue that holds B2H6 together?
  是什么将B2H6连在一块儿的呢
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  And we'll come back to that fourteen lectures from now.
  再过14堂课我们会讲到这个
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  But there's another thing.
  现在要讲个其他的
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  There's bookkeeping that you do with Lewis structures
  根据路易斯式可以写出原子的形式电荷
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  to assign what's called formal charges; not real charges,
  这有点像记账 记下的电荷并不真实
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  just what charges you write in the formula,
  只是根据式子记下的电荷
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  and you hope they mean something.
  而你希望这具有某种意义
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  And the bookkeeping scheme you use is
  而记这笔账的原则是
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  that each atom is assigned half interest in the bonding pair.
  将成键电子对平均分给两侧的原子
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  So if there's a bonding pair,
  所以一对成键的电子
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  for bookkeeping purposes you assign one electron to each.
  按规矩被均分给两侧原子