『新东方在线托福听力』为托福考生准备了ETS托福TPO/Official 8 Lec 4听力练习：What does the professor say about early versions of the periodic table?原文题目答案解析，TPO/Official 8 Lec 4听力原文范文音频翻译。

托福TPO/Official 8 Lec 4听力原文What does the professor say about early versions of the periodic table?【新东方在线】

Narrator: Listen to part of a lecture in a Chemistry class.

The professor has been discussing the periodical table of elements.

教授：那么，大家有什么问题吗？

女学生：Harrison教授，你说元素周期表是可预测的。

Female stu: Yes, um, Professor Harrison, you were saying that the periodic table is predictive.

我明白它如何组织这些元素，但如何预测呢？

I mean I understand how it organizes the elements, but where's the prediction?

教授：好的，让我们再看一下周期表。

Pro: Ok, let’s look at our periodic table again.

它把元素按它们共有的特质分类对吗？

Ok, it groups elements into categories that share certain properties, right?

教授：它按原子数递增排序，原子数是？

Pro: And it is arranged according to increasing atomic number, which is？

女学生：是元素原子中的质子数。

Female stu: The number of protons in each atom of an element.

早期的周期表有空缺，丢失的元素。

Well, early versions of the periodic table had gaps, missing elements.

多一个质子，就成了另一种元素。

Every time you had one more proton, you had another element.

但是有相应的原子数，却不知道相应的元素是什么。

And then, oops, there'd be an atomic number, for which there was no known element.

预测正是指那个原子数确定但还仍未被发现的元素。

And the prediction was that an element with that atomic number existed somewhere, but it just hadn't been found yet.

它在表中的位置可以告诉我们它的特性。

And its location in the table would tell you what properties it should have.

对那个时候的科学家来说找到这些缺失的元素并确认它们预定的特质是件很令人激动的事。

It was really pretty exciting for scientists at that time to find these missing elements and confirm their predictive properties.

事实上，这让我想起来另一个非常好的例子，第43号元素。

Um, actually, that reminds me of a...of a very good example of all these, element 43.

看表格中42号及44号元素的符号。

See on the table, the symbols for elements 42 and 44.

在早期的周期表中，43号元素没有符号因为那是有43个质子数的元素尚未被发现。

Well, in early versions of the table, there was no symbol for an element 43 protons because no element with 43 protons had been discovered yet.

所以周期表上在42和44号元素中有空缺。

So the periodic table had a gap between elements 42 and 44.

之后在1925年，由一位名叫Ida Tack的科学家带领的化学家团队声称他们找到了43号元素。

And then in 1925, a team of chemists led by a scientist named Ida Tacke claimed that they had found element 43.

他们正在使用一项相对较新的技术X射线光谱学检查一种矿石样本。

They had been using a relatively new technology called X-ray spectroscopy, and they were using this to examine an ore sample.

他们称找到了有43个质子的元素。

And they claimed that they'd found an element with 43 protons.

男学生：Harrison教授，那为什么我们元素周期表中43号元素是Tc？

Male stu: Um, Professor Harrison, then, how come in my periodic table here, element 43 is Tc?

Actually, um, that's the point I'm coming to.

当时几乎没有人相信Tack发现了新元素。

Hardly anyone believed that Tacke'd discovered a new element.

因为那时X射线光谱学是新方法。

X-ray spectroscopy was a new method at that time.

他们无法分离出足够多的Masurium作为使人信服的样本。

And they were never able to isolate enough Masurium to have a weighable sample to convince everyone of the discovery.

但是后来，12年后，1937年，另一支队伍首次使用回旋加速器合成了一种元素。

But then, 12 years later in 1937, a different team became the first to synthesize an element using a cyclotron.

教授：对，但是他们将它命名为Technetium以强调它是由技术人工合成的。

Pro: That's right, but they named it Technetium to emphasize that it was artificially created with technology.

人们认为人工合成这一元素是唯一得到它的方法。

And people thought that synthesizing this element, making it artificially was the only way to get it.

我们至今无法在自然界中找到它。

We still hadn't found it occurring in nature.

43号元素，无论称为Masurium还是Technetium，是具有放射性的。

Now element 43, whether you call it Masurium or Technetium, is radioactive.

女学生：放射性元素会衰变，它会转变成其他元素。

Female stu: It decays, it turns into other elements.

哦，这是不是解释了为什么它在元素周期表中曾一度缺失？

Oh, so does that explain why it was missing in the periodic table?

教授：正是。由于43号元素放射性的衰变，它不能长久存在。

Pro: Exactly, because of its radioactive decay, element 43 doesn't last very long.

因此，如果它曾经在地球上存在过，也早就衰变了。

And therefore, if that ever had been present on Earth, it would have decayed ages ago.

所以那时发现Masurium的人显然错了，而发现Technetium的人是对的。

So the Masurium people were obviously wrong, and the Technetium people were right.

现在我们知道43号元素在自然中确实存在。

Now we know that element 43 does occur naturally.

它可以从铀原子自发的裂变中自然产生。

It can be naturally generated from Uranium atoms that have spontaneously split.

猜猜看，发现Masurium的小组研究的矿石样品中含有足够的铀，分裂成一定量的Masurium。

And guess what, the ore sample the Masurium group was working with had plenty of Uranium in it, enough to split into measurable amounts of Masurium.

所以Tack的团队可能真的在矿石样品中发现了小量Masurium。

So Tacke's team might very well have found small amounts of Masurium in the ore samples.

它一但从铀中裂变后，就迅速衰变了。

It's just that once was generated from split Uranium, it decayed very quickly.

发现Masurium的化学家Ida Tack,她是第一个提出铀可以分解成小片，但她不知道这成了她发现43号元素的证据。

Ida Tacke, the chemist led the Masurium team, well, she was the first to suggest that Uranium could break up into smaller pieces, but she didn't know that that was the defense of her own discovery of element 43.

男学生：所以是我们这版的周期表错了？

Male stu: So is my version of the periodic table wrong?

Should element 43 really be called Masurium?

教授：也许，但是你们知道已经过去那么久这很难说Ida Tack的队伍是否发现了43号元素。

Pro: Maybe, but you know it's hard to tell for sure after all this time, if Ida Tacke's group did discover element 43.

他们没有发布关于他们使用的方法或是仪器的足够多的细节信息使我们确认。

They didn't, um, publish enough detail on their methods or instruments for us to know for sure.

但是我愿意认为43号元素被两次发现。

But I'd like to think element 43 was discovered twice.

作为Masurium，它是首次从自然裂变中发生的自然元素，作为Technetium，它首次在实验室发现。

As Masurium, it was the first element discovered that occurs in nature only from spontaneous fission, and as Technetium, it was the first element discovered in a laboratory.

当然，它是一种在被任何人发现或是制造之前，周期表让我们相信它存在的元素。

And of course, it was an element the periodic table let us to expect existed before anyone had found it or made it.

In the beginning of the lecture a student asks a question about the periodic table. How does the story of element 43 answer her question?

What does the professor say about early versions of the periodic table?

What fact inspired researchers to give the name "technetium" to element 43?

What characteristic of element 43 might explain why the scientific community doubted the findings of Ida Tacke's team?

What does the professor believe about the claim that Ida Tacke's team made about element 43?

What does the professor imply about the chemist Ida Tacke when he says this:

Pro: So, are there any questions? 
Stu: Yes, um, Professor Harrison, you were saying that the periodic table is predictive. What exactly does that mean? I mean I understand how it organizes the elements but where’s the prediction? 
Pro: Ok, let’s look at our periodic table again. Ok, it groups elements into categories that share certain properties, right? 
Stu: Uh-huh. 
Pro: And it is arranged according to increasing atomic number, which is… 
Stu: The number of protons in each atom of an element. 
Pro: Right, well, early versions of the periodic table had gaps, missing elements. Every time you had one more proton, you had another element. And then, oops, there’d be an atomic number, for which there was no known element. And the prediction was that an element with that atomic number existed somewhere, but it just hadn’t been found yet. And its location in the table would tell you what properties it should have. It was really pretty exciting for scientists at that time to find these missing elements and confirm their predictive properties. 
Um, actually, that reminds of a ... of a very good example of all these, element 43. See on the table, the symbols for elements 42 and 44. Well, in early versions of the table, there was no symbol for an element 43 protons because no element with 43 protons had been discovered yet. So the periodic table had a gap between elements 42 and 44. 
Pro: Ok, let’s look at our periodic table again. Ok, it groups elements into categories that share certain properties, right? 
Stu: Uh-huh. 
Pro: And it is arranged according to increasing atomic number, which is… 
Stu: The number of protons in each atom of an element. 
Pro: Right, well, early versions of the periodic table had gaps, missing elements. Every time you had one more proton, you had another element. And then, oops, there’d be an atomic number, for which there was no known element. And the prediction was that an element with that atomic number existed somewhere, but it just hadn’t been found yet. And its location in the table would tell you what properties it should have. It was really pretty exciting for scientists at that time to find these missing elements and confirm their predictive properties. 
And then in 1925, a team of chemists led by a scientist named Ida Tacke claimed that they had found element 43. They had been using a relatively new technology called X-ray spectroscopy, and they were using this to examine an ore sample. 
And they claimed that they’d found an element with 43 protons. And they named it Masurium. 
Stu: Um, Professor Harrison, then, how come in my periodic table here, element 43 is Tc, that’s Technetium, right? 
Pro: Ok, let me add that. Actually, um, that’s the point I’m coming to. Hardly anyone believed that Tacke’d discovered a new element. X-ray spectroscopy was a new method at that time. And they were never able to isolate enough Masurium to have a weighable sample to convince everyone of the discovery. So they were discredited. 
But then, 12 years later in 1937, a different team became the first to synthesize an element using a cyclotron. And that element had… 
Stu: 43 protons? 
Pro: That’s right, but they named it Technetium to emphasize that it was artificially created with technology. And people thought that synthesizing this element, making it artificially was the only way to get it. We still hadn’t found it occuring in nature. 
Now element 43, whether you call it Masurium or Technetium, is radioactive. Why does that matter? What is true of a radioactive element? 
Stu: It decays, it turns into other elements. Oh, so does that explain why it was missing in the periodic table? 
Pro: Exactly, because of its radioactive decay, element 43 doesn’t last very long. And therefore, if that ever had been present on Earth, it would have decayed ages ago. So the Masurium people were obviously wrong, and the Technetium people were right. Right? Well, that was then, now we know that element 43 does occur naturally. It can be naturally generated from Uranium atoms that have spontaneously split. And guess what, the ore sample the Masurium group was working with had plenty of Uranium in it enough to split into measurable amounts of Masurium. So Tacke’s team might very well have found small amounts of Masurium in the ore sample. It’s just that once was generated from split Uranium, it decayed very quickly. 
And you know here’s an incredible irony, Ida Tacke, the chemist led the Masurium team, well, she was the first to suggest that Uranium could break up into smaller pieces, but she didn’t know that that was the defense of her own discovery of element 43. 
Stu: So is my version of the periodic table wrong? Should element 43 really be called Masurium? 
Pro: Maybe, but you know it’s hard to tell for sure after all this time, if Ida Tacke’s group did discover element 43. 
They didn’t, um, publish enough detail on their methods or instruments for us to know for sure. But I’d like to think element 43 was discovered twice. As Masurium, it was the first element discovered that occurs in nature only from spontaneous fission, and as Technetium, it was the first element discovered in a laboratory. And of course, it was an element the periodic table let us to expect existed before anyone had found it or made it. 
And you know here’s an incredible irony, Ida Tacke, the chemist led the Masurium team, well, she was the first to suggest that Uranium could break up into smaller pieces, but she didn’t know that that was the defense of her own discovery of element 43.

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