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

是金属元素，原子序数是27。

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

而 fiftith 才是序数词的正确写法。

(END VIDEOTAPE) (BEGIN VIDEO CLIP) AZUZ (voice-over): Ten-second trivia: Which element, which forms more compounds than any other, is represented by an atomic number of 6?

视频结束)阿祖兹(画外音): 10秒钟的小知识: 哪个元素，比其他元素能形成更多的化物，而且它的原子序数是6?

Even before World War Two, scientists had known about the potential energy inside uranium, the heaviest metal in the periodic table a diagram which groups the chemical elements into rows and columns according to their atomic number and symbol.

甚至在第二次世界大战前，科学家们就已经知道铀内部的能。铀是元素周期表中最重的金属，元素周期表是根据原子序数和原子符号将化学元素分成行和列的图表。

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

这些元素中，哪一个的原子序数是六，是已知宇宙中最丰富的元素一？

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

一种元素的原子序数是其原子核中的质子数。

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

有118种已知的元素，每种元素都是按原子序数排列的。

We use ordinal numbers to see which comes first.

当我们看是哪个先的时候，使用序数。

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

最后，你可能还会听到序数用作形容词。

Now I gave you lots of different examples about how nouns can be unique and we also talked about how " the" should usually be used with ordinal numbers, when they're adjectives.

那么我给了你很多不同的例子说明什么才是特有名词，我们也谈论了 " the" 如何用于序数词，在它们用作形容词时。

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

原子序数为11，下面哪个元素的符号来自拉丁词“natrium”？

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

元素周期表是所有化学元素按原子序数有序排列的表。

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

大家会看到数字出现在这里，它会是一个序数词。

It's a, hydrogen, the lightest of all gases which come at the very start of the periodic table, having the atomic number 1.

答案是a选项——氢，它是位于元素周期表最开始位置的所有气体中最轻的元素，原子序数是1。

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

在这两个例子中，序数的作用都像一个名词。

This is just waste of space.

而且我们很少会将看起来很累赘的序数直接写在日期上。

We have atomic number across the bottom.

我们在底部有原子序数。

Their prediction is that nuclei containing 184 neutrons (which would have atomic numbers in the 120s) will hang around for sensible amounts of time-possibly as long as several million years.

他们预测，有184个中子的原子核（原子序数应在120-130间）会稳定出现足够长的时间——也许是几百万年。

Unbeknownst to Mendeleev, he had correctly ordered the elements by atomic number — the number of protons in the atomic nucleus.

门捷列夫不知道的是，他已经按照原子序数（原子核中的质子数）正确地对元素进行了排序。

Ordinal numbers also can act as adverbs.

序数也可以充当副词。