Pro:So, are there any questions?
教授:那么,有什么問題嗎?
Stu:Yes, um, Professor Harrison, you were saying that the periodic table is predictive.
學生:Harrison教授,你說元素周期表是可預測的,
What exactly does that mean?
究竟是什么意思呢?
I mean I understand how it organize the elements but where's the prediction?
我明白它如何組織這些元素,但如何預測呢?
Pro:Ok, let's look at our periodic table again.
教授:好的,讓我們再看一下周期表。
Ok, it is a group of elements in the categories that share certain properties, right?
它把元素按其共有的特質分類對嗎?
Stu:Um-huh.
學生:是的。
Pro:And it is ranged according to increasing atomic number, which is…
教授:它按原子數遞增排序,這個原子數就是…
Stu:The number of protons in each atom of an element.
學生:是元素原子中的質子數。
Pro:Right, well, early versions of the periodic table had gaps, missing elements.
教授:對,早期的周期表有空缺,丟失的元素。
Every time you had one more proton, you had another element.
每多一個質子,就有了另一種元素。
And then, oops, there have been atomic number, for which there's no known element.
但是有相應的原子數,卻不知道相應的元素是什么。
And the prediction was that the element, with that atomic number existed someway, but it just haven't been found yet.
而預測正是指那個原子數確定但還仍未被發現的元素。
And its location in the table would tell you what properties that you should have.
它在表中的位置可以告訴我們它的特性。
It was really pretty exciting for scientists at that time to find these missing elements and confirm their predictive properties.
對那個時候的科學家來說找到這些缺失的元素并確認它們的預定特質是件很令人激動的事。
Um, actually, that reminds other, other very good example of all these, element 43.
事實上,這讓我想起來另一個非常好的例子,就是第43號元素。
See on the table, the symbol for element 42 and 44.
看表格中42號及44號元素的符號。
In early versions of the table, there was no symbol for element 43 protons because no element with 43 protons had been discovered yet.
在早期的周期表中,43號元素沒有符號因為那是有43個質子數的元素尚未被發現。
So the periodic table had gap between elements 42 and 44.
所以周期表上在42和44號元素中間有空缺。
And then in 1925, a team of chemists led by scientist named Ida Tack's claimed they had found element 43.
而后在1925年,由一位名叫Ida Tack的科學家帶領的化學家團隊聲稱他們找到了43號元素。
They had been using a relatively new technology called X-ray spectroscopy, and they were using this to examine an ore sample.
他們正在使用一項相對較新的技術X射線光譜學檢查一種礦石樣本。
And they claimed that they'd found an element with 43 protons.
他們稱找到了有43個質子的元素,
And they named it Masuria.
他們將其命名為Masuria。
Stu:Um, Professor Harrison, then, how come in my periodic table, here, element 43 is Tc, that's Technetium, right?
學生:Harrison教授,那為什么我們元素周期表中43號元素是Tc,那是锝對嗎?
Pro:Ok, let me add that.
教授:好吧,我補充一下,
Actually, um, that's the point I'm coming to.
實際上,我馬上就要講到這點。
Hardly anyone believed that Tack's discovered the new element.
當時幾乎沒有人相信Tack發現了新元素。
X-ray spectroscopy was a new method at that time.
因為那時的X射線光譜學是新方法,
And they were never able to isolate enough Masurium to have available sample to convince everyone the discovery.
他們無法分離出足夠多的Masurium作為使人信服的樣本。
So they were discredited.
所以他們沒有被人們相信。
But then, 12 years later in 1937, a different team became the first to synthesize the element using a cyclotron. And that element had…
但是后來,12年后的1937年,另一支隊伍首次使用回旋加速器合成了一種元素。而這種元素有…
Stu:43 protons?
學生:43個質子?
Pro:That's right, but they named it Technetium to emphasize that it was artificially created with technology.
教授:對,但是他們將它命名為Technetium以強調它是由技術人工合成的。
And people thought that synthesizing these elements, it artificially was the only way to get it.
而且人們認為人工合成這一元素是唯一得到它的方法。
We still haven't found it currently in nature.
我們至今無法在自然界中找到它。
Now element 43 would be called Masurium or Technetium is radioactive.
43號元素,無論是Masurium還是Technetium,都是具有放射性的。
Why is that matter?
這有什么關系呢?
What is true of radioactive element?
放射性元素有何特征?
Stu:It decays it turns into other elements.
學生:放射性元素會衰變,轉變成其他元素。
Oh, so does that explain why was missing in periodic table?
哦,這是不是解釋了為什么它在元素周期表中曾一度缺失?
Pro:Exactly, because of radioactive decay, element 43 doesn't last very long.
教授:正是。由于放射性的衰變,43號元素不能長久存在。
And therefore, if that ever had been present on earth, it would decay ages ago.
因此如果它曾經在地球上存在過,也早就衰變了。
So the Masurium people were obviously wrong, and the Technetium people were right. Right?
所以那時發現Masurium的人顯然錯了,而發現Technetium的人是對的。是吧?
Well, that was then, now we know that element 43 does occur naturally.
不過那是以前,現在我們知道43號元素在自然中確實存在。
It can be naturally generated from Uranium atom that has spontaneous split.
它可以從鈾原子自發的裂變中自然產生。
And guess what, the ore sample that the Masurium group was working with had plenty of Uranium enough to split into measurable amount of Masurium.
猜猜看發生了什么,發現Masurium的小組研究的礦石樣品中含有足夠的鈾,分裂成一定量的Masurium。
So Tack's team might very well have found small amounts of Musurium in the ore sample just that once was generated from split Uranium decayed very quickly.
所以Tack的團隊可能真的在礦石樣品中發現了小量Masurium,只是它一從鈾裂變中產生后就迅速衰變了。
And you know here's an incredible irony,
而且很諷刺的是,
Ida Tack, led the chemist of that Musurium team, and were she the first to suggest that Uranium could break up into small pieces but she didn't know that that was the defense of her own discovery of element 43.
發現Masurium的化學家Ida Tack,她是第一個提出鈾可以分解成小片,但她不知道這成了她發現43號元素的證據。
Stu:So is my version of periodic table wrong? Should element 43 really be called Musurium?
學生:所以是我們這版的周期表錯了?43號元素應該稱為Masurium?
Pro:Maybe, but it's hard to tell for sure after all this time, if Ida Tack's group did discover element 43.
教授:也許,但是你們知道已經過去那么久,很難說 Ida Tack 的隊伍是否發現了 43 號元素。
They didn't, um, publish enough details on their method or instruments for us to know for sure.
他們沒有發布關于他們使用的方法或是儀器的足夠多的細節信息使我們確認。
But I'd like to think element 43 was discovered twice.
但是我愿意相信 43 號元素被兩次發現。
As Musurium, it was first element to discover that occurs in nature only from spontaneous vision,
作為 Masurium,它是首次從自然裂變中發生的自然元素,
and as Technetium, it was the first element discovered in the laboratory.
作為Technetium,它首次在實驗室發現。
And of course, it was an element the periodic table let us to expect existed before anyone had found it or made it.
當然,它是一種在被任何人發現或是制造之前,周期表讓我們相信它存在的元素。