Word tips

periodic table 元素周期表

proton n. 質(zhì)子

element n. 元素

spectroscopy n. 光譜學(xué)

ore n. 礦石

Masurium n. 鎷元素（锝元素的舊稱）

weighable adj. 可量重的

discredit v. 使不相信

synthesize v. （通過(guò)化學(xué)手段或生物過(guò)程）合成

cyclotron n. 回旋加速器

Technetium n. 锝元素

radioactive adj. 放射性的；有輻射的

Listen to the following recording and answer questions 1-3.

1) A. Early versions listed two names for some elements.

B. Early versions had the incorrect atomic number for some elements.

C. Early versions were not as easy to use as modern version.
D. Early versions did not list all the elements for all atomic numbers.


2) A. The element was radioactive.

B. The element was derived from uranium.

C. The element was created artificially.
D. The element was found using x-ray spectroscopy.


3) A. Element 43 has a very fast rate of decay.
B. Element 43 always contains small amount of other elements.
C. Element 43 cannot be created artificially.
D. Element 43's radioactivity makes it easy to isolate and measure.

聽(tīng)力原文：

Professor: 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 had been atomic number, for which there's 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 me of... of a... of a very good example of all these, element 43. See on the table, the symbols for element 42 and 44？ Well, in early versions of the table, there was no symbol for an element with 43 protons because no element with 43 protons had been discovered yet. So the periodic table had a gap between elements 42 and 44. And then in 1925, a team of chemists led by a scientist named Ida Tack 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.

Hardly anyone believed that Tack's 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 the element using a cyclotron, 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 haven't found it currently 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?

Student: It decays. It turns into other elements. Oh, so does that explain why it was missing in periodic table?

Professor: Exactly. Because of its radioactive decay, element 43 doesn't last very long. And therefore, if it ever had been present on earth, it would decay 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 atom that has spontaneously split.

Questions:

1. What does the professor say about early versions of the periodic table?
2. What fact inspired researchers to give the name “technetium” to element 43?
3. What characteristic of element 43 might explain why the scientific community doubted the findings of Ida Tacke's team?

參考譯文：

教授：嗯，周期表的早期版本中有空白的地方，有缺失的元素。每當(dāng)你多找到一個(gè)質(zhì)子，你就又找到了一個(gè)元素。之后，哦，有些原子數(shù)目沒(méi)有已知元素相對(duì)應(yīng)。那周期表的預(yù)測(cè)性是說(shuō)，這個(gè)元素的原子數(shù)目在某個(gè)地方是存在的，只是這個(gè)元素尚未被發(fā)現(xiàn)罷了。這個(gè)元素在表中的位置能告訴你它應(yīng)該具有的性質(zhì)。對(duì)于當(dāng)時(shí)的科學(xué)家來(lái)說(shuō)，找尋這些缺失的元素并證實(shí)它們被預(yù)測(cè)出的性質(zhì)是令人很興奮的事。

嗯，事實(shí)上，這讓我想起了一個(gè)很好的例子，關(guān)于43號(hào)元素?？纯粗芷诒砩系?2和44號(hào)元素的符號(hào)。在周期表的早期版本中，具有43個(gè)質(zhì)子的元素沒(méi)有符號(hào)表示，這是因?yàn)楫?dāng)時(shí)還沒(méi)發(fā)現(xiàn)具有43個(gè)質(zhì)子的元素。因此，在周期表上第42和44號(hào)元素之間留有空缺。之后到了1925年，一組化學(xué)家在科學(xué)家艾達(dá)塔克的帶領(lǐng)下宣布發(fā)現(xiàn)了第43號(hào)元素。它們用了一個(gè)相對(duì)較新的技術(shù)，叫做X光光譜。它們用此技術(shù)檢測(cè)了一個(gè)礦石樣本。然后他們宣布他們發(fā)現(xiàn)了具有43個(gè)質(zhì)子的元素并把它命名為鎷元素。

幾乎沒(méi)有人相信塔克的小組發(fā)現(xiàn)了新元素。X光光譜在當(dāng)時(shí)是個(gè)新方法，而且他們從沒(méi)分離足量的鎷元素去得到可測(cè)量的樣本，讓人們相信這一發(fā)現(xiàn)。因此人們不相信他們。但是12年后，到了1937年，另一個(gè)小組最先用回旋加速器合成出了這種元素。不過(guò)他們把這個(gè)元素命名為锝元素，來(lái)強(qiáng)調(diào)它是通過(guò)技術(shù)人工創(chuàng)造出來(lái)的。人們認(rèn)為人工合成這些元素是唯一的獲取方式。我們當(dāng)時(shí)在自然中仍未發(fā)現(xiàn)它?，F(xiàn)在，第43號(hào)元素會(huì)被叫做鎷元素或者锝元素，具有放射性。為什么這很重要呢？放射性元素有什么特征？

學(xué)生：它能衰變，轉(zhuǎn)變成其它元素。哦，這就解釋了它為什么沒(méi)出現(xiàn)在周期表上了？

教授：沒(méi)錯(cuò)，由于放射性衰變，第43號(hào)元素不能存在很長(zhǎng)時(shí)間。因此，即使它在地球上存在過(guò)，它在很久很久以前就衰變了。因此，發(fā)現(xiàn)鎷元素的人顯然是錯(cuò)的，發(fā)現(xiàn)锝元素的人是對(duì)的，是吧？嗯，那是之前的觀點(diǎn)?，F(xiàn)在我們知道第43號(hào)元素確實(shí)在自然中存在。它能從鈾原子中自然分裂出來(lái)。


參考答案：

1. D 2. C 3. A?