double bond

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So really, you can not ever rotate a double bond, it makes your molecule very rigid.
實(shí)際上，你不能轉(zhuǎn)動一個雙鍵，它使得你的分子很堅(jiān)固。
So if we look at its length, it's actually shorter than a single bond, but longer than a double bond.
因此如果我們看它的鍵長的話，它實(shí)際上比單鍵更短，卻比雙鍵更長。
Electrons can cause this double bond to rotate, which places part of the wheel in close proximity to a bulky side-molecule attached to the hub.
電子可以使這個雙拼接口旋轉(zhuǎn)，使得輪子的一部分緊靠連接輪轂的一個大型從屬分子上。

So if we look at its length, it's actually shorter than a single bond, but longer than a double bond.
因此如果我們看它的鍵長的話，它實(shí)際上比單鍵更短，卻比雙鍵更長。
麻省理工公開課 - 化學(xué)原理課程節(jié)選
And we find the same thing for these two atoms here, it's not actually a double bond, it's somewhere between a single bond and a double bond.
而且我們發(fā)現(xiàn)這兩個原子的情況是一樣的，它其實(shí)不是一個雙鍵，而是介于單鍵與雙鍵之間的。
麻省理工公開課 - 化學(xué)原理課程節(jié)選
And something that we'll see later on is that triple bonds, for example, are going to be stronger than a corresponding double bond or a corresponding single bond.
而我們以后還會看到三鍵，舉例來說，應(yīng)該更強(qiáng)，相較于相應(yīng)的雙鍵,或者相應(yīng)的單鍵來說。
麻省理工公開課 - 化學(xué)原理課程節(jié)選

The citral molecule has a double bond in its tail, which, when it comes into contact with acid, forms a circular structure.
FORBES: Magazine Article

a type of chemical bond consisting of two covalent bonds linking two atoms in a molecule