Why is it called an ionic bond?

为什么叫离子键？

This is called a polar covalent bond.

这称为极性共价键。

This straightforward sort of bond is called a sigma bond.

这种简单的债券称为 sigma 债券。

These relationships on which the individual with borderline personality disorder depends are called selfobject bonds.

边缘性人格障碍患者所依赖的这些关系被称为自体客体纽带。

Water has a special kind of interaction between molecules that most other substances don't have, and it's called a hydrogen bond.

水，同大多数其他物质不同，水分子之间有一种独特的的相互作用叫做氢键。

Single bonds, also called sigma bonds, are pretty simple, and carbon atoms attached by them can rotate around the bond freely.

单键，也称为西格玛键，非常简单，它们所附着的碳原子可以围绕键自由旋转。

They engage in additional kind of loose relationships with other neighboring hydrogen and oxygen atoms. These loose, somewhat fleeting relationships are called hydrogen bonds.

它们与其他相邻的氢原子和氧原子建立了一种额外的松散关系。这些松散的、稍纵即逝的关系被称为氢键。

But there is a twist when it comes to the bond that this Dutch water authority issued in 1624. It didn't have an expiration date, so it's what's called a perpetual bond.

但荷兰水务局于 1624 年发行的债券却有一个不同之处。它没有到期日，所以这就是所谓的永续债券。