Cobalt is a metallic element, atomic number 27 in the period table.

钴是金属，子序是27。

And fiftieth is the correct way to write the ordinal number.

而 fiftith 才是序词的正确写法。

When you're ordering things, so when ordinal numbers like second, fifth, are used as adjectives.

当你在给某些事物排序时，那么这时序词是第二，第五，作为冠词使用。

An element's atomic number is the number of protons in its nucleus.

一种的子序是其子核中的质子。

There are 118 known elements, each organized by atomic number.

有118种已知的，每种是按子序排列的。

We use ordinal numbers to see which comes first.

当我们看是哪个先的时候，使用序。

Finally, you might also hear ordinal numbers used as an adjective.

最后，你可能还会听到序用作形容词。

But in the Olympic games, ordinal numbers are of central importance.

但是在奥运会上，序才是最重要的。

This is just waste of space.

而且我们很少会将看起来很累赘的序直接写在日期上。

The periodic table is an organized display of all the chemical elements in order by atomic number.

周期表是所有化学按子序有序排列的表。

All of the other ordinal numbers end in a TH.

所有其他以TH结尾的序词。

Ordinal numbers are numbers that show the order of things.

序词表示的是事物的顺序。

Ordinal numbers suggest an order of things – think the order of winners in the Olympics.

序代表事物的顺序--想想奥运会获胜者的顺序。

Ordinal numbers can act as nouns, adjectives, or adverbs.

序可以充当名词、形容词或副词。

Which of these elements, who's atomic number is six is one of the most abundant elements in the known universe?

这些中，哪一个的子序是六，是已知宇宙中最丰富的之一？

With an atomic number of 11, which of these elements gets its symbol from the Latin word " natrium" ?

子序为11，下面哪个的符号来自拉丁词“natrium”？

You'll see a number up here, it'll be an ordinal number.

大家会看到字出现在这里，它会是一个序词。

Ordinal numbers are one important area of grammar that connects with the Olympics.

序是与奥运会相关的一个重要语法领域。

In both cases, the ordinal number is acting like a noun.

在这两个例子中，序的作用一个名词。

Ordinal numbers also can act as adverbs.

序也可以充当副词。