沪江论坛社区--《经济学家》读译参考（145）：那是一种气体

TEXT 145

Chemistry

化学

It's a gas

那是一种气体（译/陈继龙）

May 3rd 2007

From The Economist print edition

A gaseous metal may just have been discovered

也许才被发现的一种气态金属

IN CHEMISTRY, less is more. The subject's practitioners have a horror of what they call “bucket chemistry”—even if the buckets in question are merely test-tube sized. Finesse comes from the ability to analyse small quantities accurately. And the smallest possible quantity in chemistry is, of course, a single atom.

在化学上，少一点即多一些。从事化学研究的人十分厌恶所谓的“提桶化学（bucket chemistry）”——即使所研究的提桶仅有试管一般大小亦然。能够进行准确微定量分析那才叫本事，而单一的原子无疑就是化学上能够进行最小定量分析的对象了。

Robert Eichler, of the Paul Scherrer Institute in Switzerland, and his colleagues have not quite managed that, but they have come close. As they report in this week's Nature, they have characterised the properties of a recently discovered element using two atoms. （1）In doing so, they have shown that the predictions of chemistry's central blueprint, Dmitri Mendeleev's periodic table, extend reliably into the realm of heavy, short-lived, radioactive elements that do not exist in nature. They may also have found the first metal that is a gas at room temperature.

瑞士保罗•谢勒研究所（Paul Scherrer Institute）的罗伯特•艾希勒（Robert Eichler）和他的同事们对此虽不十分在行，但已经接近了这个水平。在本周出版的《自然》杂志上，他们报道通过两个原子表征了一种新近发现元素的特性。与此同时，他们指出，按照化学的中心蓝图 ——季米特里•门捷列夫（Dmitri Mendeleev）元素周期表预测下去，完全可以延伸至自然界不存在、半衰期短的放射性重元素领域。此外，他们还发现了首个在室温下为气态的金属元素。

An electronic shell game

电子层游戏

（2） As generations of chemistry teachers have laboured to convey, the periodic table consists of rows and columns. Adjacent elements in a row differ from one another by a proton in the nucleus and an electron orbiting that nucleus. The periodic table works because the electrons like to organise themselves in concentric shells. Outer shells are bigger than inner ones, but each has a fixed capacity. When a shell is full, the next element in the series starts a new shell, and that marks the beginning of a new row of the table. The larger capacity of outer shells means that the rows get longer, and so more columns appear.

多少年来化学老师潜心教授的是，元素周期表由行与列组成，每一行相邻的两个元素原子核之间相差一个质子及绕核旋转的一个电子。元素周期表之所以可行，是因为电子往往要在同心电子层中自行排列。外层比内层大，但每层容量均固定不变。当某一层排满电子时，周期表中的下一元素就启用新的一层，此即标志着周期表新的一行元素的开始。外层容量越大，行就越长，列也就越多。

It is the columns that are the interesting part of the table. Elements in the first column all have one electron in their outermost shell. Those in the second column have two outer electrons, and so on. Only electrons in the outer shell can form chemical bonds, so the elements in each column are chemically similar.

列是周期表中有意思的部分。第一列元素最外电子层内均有一个电子，第二列元素则含有两个电子，依此类推。只有外层内的电子才会形成化学键，因此每一列中各元素化学性质均相似。

What Dr Eichler and his colleagues wanted to find out was whether the pattern would continue to hold good for the monster elements coming out of the Joint Institute for Nuclear Research in Dubna, Russia. （3） The reason to suspect it might not is that as the shells get bigger, the velocity of the electrons within them increases. At some point they will be travelling so fast that the way they bond will be affected by Albert Einstein's theory of relativity, which departs from classical theories at speeds close to that of light.

艾希勒和他的同事们希望弄清的是，这一模式是否也适用于俄罗斯杜伯纳联合核研究所发现的超大元素。有人怀疑可能并不适用，原因在于当电子层增大时，层内电子运动速度也加快。从某种意义上看，根据爱因斯坦相对论（当达到接近光速的速度时，相对论就背离了经典理论），电子运动速度加快，电子间相互结合的方式就会受影响。

The object of Dr Eichler's study was element number 112. This was first made in 1996, but has still not received an official name (it goes under the ugly moniker of ununbium). In non-relativistic theory, it should behave like the other members of its column—zinc, cadmium and mercury—and be a metal. But some relativistic calculations suggested it might actually behave like a different element, the inert (and non-metallic) gas, radon.

艾希勒研究的是第112号元素。该元素在1996年首次合成，但至今仍未予正式命名（目前名为ununbium，很难看）。从非相对论意义上来看，它应表现出同列其它元素——锌、镉和汞——的特性，且应是一种金属。但基于相对论进行的计算表明，它更像一种独特元素、惰性（非金属）气体氡。

Unfortunately for chemists, ununbium can be made only a few atoms at a time (by bombarding plutonium atoms with calcium atoms), and those atoms that are made have a half-life of a mere four seconds. Dr Eichler nevertheless took up the challenge. With the aid of colleagues in Dubna, he managed to get two atoms of ununbium to stick to a sheet of gold. What is more, by using a trick called thermochromatography he was able to measure the energy released when this happened. All that remained was to see whether this energy release more resembled that of gold reacting with mercury or with radon.

遗憾的是，化学家们合成第112号元素时，每次仅能获得很少的几个原子（用钙原子轰击钚原子），而且这些原子的半衰期仅为4秒。但艾希勒迎难而上，在杜伯纳研究所同行的协助下，成功地将第112号元素的两个原子粘附到一块金片上，同时利用热色谱技术对粘附时释放的能量进行了测定。接下来要弄清的问题就是，释放的能量是否与金汞或金氡反应时释放的能量相同。

Mendeleev 1: Einstein 0

门捷列夫1:0爱因斯坦

（4） By a convenient fluke, the process that produces ununbium also generates radon, while adding neodymium yields mercury, too, so Dr Eichler's comparisons were to hand. The upshot is that the ununbium/gold reaction resembled that with mercury and not that with radon. However, the interaction energy reveals more than just chemical affinity. It also gives an idea of how volatile an element is, even if only one or two atoms are available.

凑巧的是，合成第112号元素的同时也会产生氡，当加入钕时还会产生汞，这为艾希勒作比较时提供了便利。结果显示，第112号元素与金之间的反应，同金汞反应相近，但不同于金氡反应。这种相互作用能（interaction energy）不仅能表现出化学亲和力的大小，尚可揭示某种元素的挥发性强弱——即便只有一个或两个原子。

（5） Whether an element is a solid, a liquid or a gas depends on how its atoms interact with each other. But how they interact with other substances, such as gold, acts as a proxy for that behaviour. Dr Eichler's previous work has established a graph that describes this proxy. Although he cannot be sure, there is a good chance that if you could make ununbium in large quantities, it would not only be metallic, but would also be a gas at room temperature.

一种元素到底属于固体、液体还是气体，要视其原子之间的相互作用而定，而它们与其它物质（如金）之间的相互作用，可相当于前一相互作用的“代理方式”。艾希勒在其以前的研究中，已经绘制出表现这种“代理方式”的曲线图。虽然他还不可能有确切结论，但至少找到了一个很好的机会：那就是如果第112号元素得以大量合成，那么它不仅是金属元素，而且在室温下还会呈现气态。

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英译汉（请将划线部分英文翻译成中文）：