So, let's just take a quick example to show how not completely you can use these periodic trends, that there are limits.

那么，让我们举一个小例子来看一下,你是如何不能将元素周期律用在所有地方的，它是有局限性的。

麻省理工公开课 - 化学原理课程节选

But you actually need to keep a few caveats in mind as you do this, which is the fact that trends predict a lot of chemical properties, but they can't predict everything in terms of biological properties.

不过在你使用的过程中,需要牢记一些注意事项,那就是元素周期律可以预言很多化学性质，但是不能预言一切性质,比如生物学性质。

麻省理工公开课 - 化学原理课程节选

So anyway, when we talk about periodic trends, it doesn't always match up.

无论如何，当我们讨论元素周期律时，要知道它并不是总能与实际情况相符。

麻省理工公开课 - 化学原理课程节选

All right. So that is an anti-example of using periodic trends.

好的，这是一个关于使用元素周期律的反例。

麻省理工公开课 - 化学原理课程节选

So if we consider lithium, potassium, and sodium, they're all together in the same group on the periodic table, knowing what we do about biology we can immediately think of sodium and potassium, or even just knowing what you know about table salt, for example, that these are two elements that we find, and particularly in the ion form in very high concentrations in our body.

我们来考虑一下锂，钾和钠，它们都在周期表中的同一族里，想要知道我们将元素周期律,用到生物学会怎么样，我们首先想到的就是钠和钾，甚至只需要知道食盐，我们发现它们是以很高浓度的离子形式,存在于我们体内的两种元素。

麻省理工公开课 - 化学原理课程节选