9 Essential Facts About Carbon 有关碳的九大基本事实

伊娃·冯夏普尔

It can be glittering and hard. It can be soft and flaky. It can look like a soccer ball. Carbon is the backbone of every living thing—and yet it just might cause the end of life on Earth as we know it. How can a lump of coal and a shining diamond be composed of the same material？ Here are nine things you probably didnt know about carbon.

1. Its the “duct tape of life.”

Its in every living thing， and in quite a few dead ones. “Water may be the solvent of the universe，” writes Natalie Angier in her classic introduction to science， The Canon， “but carbon is the duct tape of life.” Not only is carbon duct tape， its one hell of a duct tape. It binds atoms to one another， forming humans， animals， plants and rocks. If we play around with it， we can coax it into plastics， paints， and all kinds of chemicals.

2. Its one of the most abundant elements in the universe.

It sits right at the top of the periodic table， wedged in between boron and nitrogen. Atomic number 6， chemical sign C. Six protons， six neutrons， six electrons. It is the fourth most abundant element in the universe after hydrogen， helium， and oxygen， and 15th in the Earths crust. While its older cousins hydrogen and helium are believed to have been formed during the tumult of the Big Bang， carbon is thought to stem from a buildup of alpha particles in supernova explosions， a process called supernova nucleosynthesis.

3. Its named after coal.

While humans have known carbon as coal and—after burning—soot for thousands of years， it was Antoine Lavoisier who， in 1772， showed that it was in fact a unique chemical entity. Lavoisier used an instrument that focused the Suns rays using lenses which had a diameter of about four feet. He used the apparatus， called a solar furnace， to burn a diamond in a glass jar. By analyzing the residue found in the jar， he was able to show that diamond was comprised solely of carbon. Lavoisier first listed it as an element in his textbook Traité ?lémentaire de Chimie， published in 1789. The name carbon derives from the French charbon， or coal.

4. It loves to bond.

It can form four bonds， which it does with many other elements， creating hundreds of thousands of compounds， some of which we use daily. （Plastics！ Drugs！ Gasoline！） More importantly， those bonds are both strong and flexible.

5. Nearly 20 percent of your body is carbon.

May Nyman， a professor of inorganic chemistry at Oregon State University in Corvallis， Oregon tells Mental Floss that carbon has an almost unbelievable range. “It makes up all life forms， and in the number of substances it makes， the fats， the sugars， there is a huge diversity，” she says. It forms chains and rings， in a process chemists call catenation. Every living thing is built on a backbone of carbon （with nitrogen， hydrogen， oxygen， and other elements）. So animals， plants， every living cell， and of course humans are a product of catenation. Our bodies are 18.5 percent carbon， by weight.

And yet it can be inorganic as well， Nyman says. It teams up with oxygen and other substances to form large parts of the inanimate world， like rocks and minerals.

6. We discovered two new forms of it only recently.

Carbon is found in four major forms： graphite， diamonds， fullerenes， and graphene. “Structure controls carbons properties，” says Nyman. Graphite （“the writing stone”） is made up of loosely connected sheets of carbon formed like chicken wire. Penciling something in actually is just scratching layers of graphite onto paper. Diamonds， in contrast， are linked three-dimensionally. These exceptionally strong bonds can only be broken by a huge amount of energy. Because diamonds have many of these bonds， it makes them the hardest substance on Earth.

Fullerenes were discovered in 1985 when a group of scientists blasted graphite with a laser and the resulting carbon gas condensed to previously unknown spherical molecules with 60 and 70 atoms. They were named in honor of Buckminster Fuller， the eccentric inventor who famously created geodesic domes with this soccer ball-like composition. Robert Curl， Harold Kroto， and Richard Smalley won the 1996 Nobel Prize in Chemistry for discovering this new form of carbon.

The youngest member of the carbon family is graphene， found by chance in 2004 by Andre Geim and Kostya Novoselov in an impromptu research. The scientists used Scotch tape—yes， really—to lift carbon sheets one atom thick from a lump of graphite. The new material is extremely thin and strong. The result： the Nobel Prize in Physics in 2010.

7. Diamonds arent called “ice” because of their appearance.

Diamonds are called “ice” because their ability to transport heat makes them cool to the touch—not because of their look. This makes them ideal for use as heat sinks in microchips. （Synthethic diamonds are mostly used.） Again， diamonds three-dimensional lattice structure comes into play. Heat is turned into lattice vibrations， which are responsible for diamonds very high thermal conductivity.

8. It helps us determine the age of artifacts—and prove some of them fake.

American scientist Willard F. Libby won the Nobel Prize in Chemistry in 1960 for developing a method for dating relics by analyzing the amount of a radioactive subspecies of carbon contained in them. Radiocarbon or C14 dating measures the decay of a radioactive form of carbon， C14， that accumulates in living things. It can be used for objects that are as much as 50，000 years old. Carbon dating helped determine the age of ?tzi the Iceman， a 5300-year-old corpse found frozen in the Alps. It also established that Lancelots Round Table in Winchester Cathedral was made hundreds of years after the supposed Arthurian Age.

9. Too much of it is changing our world.

Carbon dioxide （CO2） is an important part of a gaseous blanket that is wrapped around our planet， making it warm enough to sustain life. But burning fossil fuels—which are built on a carbon backbone—releases more carbon dioxide， which is directly linked to global warming. A number of ways to remove and store carbon dioxide have been proposed， including bioenergy with carbon capture and storage， which involves planting large stands of trees， harvesting and burning them to create electricity， and capturing the CO2 created in the process and storing it underground. Yet another approach that is being discussed is to artificially make oceans more alkaline in order to let them to bind more CO2. Forests are natural carbon sinks， because trees capture CO2 during photosynthesis， but human activity in these forests counteracts and surpasses whatever CO2 capture gains we might get. In short， we dont have a solution yet to the overabundance of CO2 weve created in the atmosphere.

可以又亮又硬，也可以又软又脆，还可以外表像个足球——碳是构成所有生物的基本物质，正如我们所知，它也可能终结地球上的所有生物。一块煤和一枚亮晶晶的钻石怎么会是相同物质组成的呢？以下是你可能不知道的有关碳的9个事实。

1. 碳是“生命的胶带”。

碳存在于每一種活的生物体和相当数量已死亡的生物体内。纳塔莉·安吉尔在其经典的科学入门书《正典》中写道：“水可能是宇宙的溶剂，而碳是生命的胶带。”碳不仅仅是一种胶带，还是一种了不起的胶带。碳将原子与原子相互联结，形成人类、动物、植物和岩石。如果我们对碳进行加工，就能制造出塑料、颜料和各种化学制品。

2. 碳是宇宙中最丰富的元素之一。

碳位于元素周期表的顶端，在硼和氮之间。其原子序数为6，化学符号为C，有6个质子、6个中子和6个电子。碳是宇宙中第4多的元素，仅次于氢、氦和氧，地壳中则排名第15。人们认为，碳的表兄氢和氦是在宇宙大爆炸的混乱中生成的，碳则是由超新星爆炸中的α粒子堆积形成的，这个过程叫作超新星核合成。

3. 碳得名于煤。

数千年来，人们一直认为碳就是煤和煤燃烧后产生的灰烬，但1772年，安托万·拉瓦锡证明了碳实际上是一种独特的化学实体。拉瓦锡用直径约4英尺的透镜聚集太阳光线，并用名为“太阳炉”的仪器在玻璃瓶中燃烧了一颗金刚石。通过分析瓶中的残留物，拉瓦锡得以证明金刚石完全由碳组成。拉瓦锡在其1789年出版的教科书《化学基础论》中首次将碳列为一种化学元素。而碳这一名称来源于法语的charbon，也就是煤。

4. 碳易成键。

碳原子可与其他许多元素的原子形成四个共价键，创造出成千上万种化合物，其中有些正是我们日常使用的，例如塑料、药物和汽油等。更重要的是，这些键既牢固又灵活。

5. 人体将近20%都是碳。

梅·尼曼是美国俄勒冈州科瓦利斯市俄勒冈州立大学的无机化学教授。她告诉《心理牙线》杂志，碳存在范围之广令人难以置信。尼曼说：“碳构成了所有的生命形态，生成了众多物质，包括各种脂肪、各种糖，极为多样。”在化学家所称的“链化作用”的过程中，碳可以形成链和环。所有生物都是以碳为基础构成的（碳与氮、氢、氧等元素结合）。所以，动物、植物、每个活细胞——当然也包括人类——都是链化作用的产物。碳占我们体重的18.5%。

不过，尼曼表示，碳也可以是无机的。碳与氧和其他物质结合在一起，可形成无生命世界中的大部分东西，如岩石和矿物。

6. 碳的两种新形式最近几十年才被发现。

碳目前主要有四种形式：石墨、金刚石、富勒烯和石墨烯。尼曼说：“结构决定碳的性质。”石墨（写字石）是由片层结构的碳网松散连接在一起形成的，碳网就像铁丝网。用铅笔写字实际上只是把石墨层划到纸上。相比之下，金刚石是三维连接的。这种异常牢固的键只有施以巨大的能量才能打破。金刚石由于具有许多这样的键，所以成为地球上最坚硬的物质。

富勒烯是在1985年发现的。当时，一群科学家用激光对石墨进行爆炸处理，生成的碳气凝聚成了具有60和70个原子的球形分子，这是前所未知的。为纪念性格古怪的发明家巴克明斯特·富勒，这些分子以他的名字命名。富勒以发明了足球似构造的短程线穹顶闻名。罗伯特·柯尔、哈罗德·克罗托和理查德·斯莫利因发现这种新形式的碳而获得了1996年诺贝尔化学奖。

碳家族最年轻的成员石墨烯，是安德烈·盖姆和科斯提亚·诺沃肖洛夫2004年在一次即兴研究中偶然发现的。这两位科学家使用透明胶带——没错，就是胶带——从一块石墨中提起厚度为一个原子的碳层。新材料极薄且坚固。结果：二位获得了2010年诺贝尔物理学奖。

7. 金刚石被称作“冰”并非因其外表。

金刚石被叫作“冰”，是因为它们的导热能力使它们摸起来凉凉的，而不是因为其外表。这让金刚石成为微芯片散热器的理想选择。（主要使用合成金刚石。）金刚石的三维晶格结构再次发挥作用。热会转变成晶格振动，这是金刚石导热性超高的原因所在。

8. 碳有助于测定文物年代及鉴别真伪。

美国科学家威拉德·F.利比于1960年获得诺贝尔化学奖，原因是他发明了一种通过分析文物中放射性碳同位素的数量来测定文物年代的方法。放射性碳（也叫碳-14）测年法测量的是积聚在生物中的放射性碳，即碳-14的衰变含量。这种方法甚至可以用于测量距今5万年的物品。借助于碳测年法，人们测定了冰人奥兹的年龄，奥兹是在阿尔卑斯山发现的一具冻尸，距今已经5300年了。人們还采用这种方法确定，温彻斯特大教堂的兰斯洛特圆桌并非像以前认为的那样制作于亚瑟王时代，而是亚瑟王时代数百年后的产物。

9. 碳过多正改变我们的世界。

二氧化碳是包裹着我们这个星球的大气层的重要组成部分，使地球足够温暖以维持生命。但是，燃烧以碳为基架的化石燃料会释放更多的二氧化碳，这与全球变暖直接相关。人们已经提出了许多去除和储存二氧化碳的方法，其中包括利用碳捕捉和储存来存储生物能源，而这需要种植大片树木，采伐和燃烧以产生电力，再捕捉此过程中产生的二氧化碳并将其存储在地下。另一个正在讨论的方法是人为增强海洋碱性，使之可以结合更多的二氧化碳。森林是天然的碳汇，因为树木可通过光合作用捕捉二氧化碳，但是人类在森林中的活动抵消甚至超过了树木对二氧化碳的捕捉。总之，我们在大气中释放了过量的二氧化碳，却还没有解决这一问题的办法。                                       □

（译者单位：郑州大学）