9 Essential Facts About Carbon 有關碳的九大基本事實

伊娃·馮夏普爾

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，也可以又軟又脆，還可以外表像個足球——碳是構成所有生物的基本物質，正如我們所知，它也可能終結地球上的所有生物。一塊煤和一枚亮晶晶的鉆石怎么會是相同物質組成的呢？以下是你可能不知道的有關碳的9個事實。

1. 碳是“生命的膠帶”。

碳存在于每一種活的生物體和相當數量已死亡的生物體內。納塔莉·安吉爾在其經典的科學入門書《正典》中寫道：“水可能是宇宙的溶劑，而碳是生命的膠帶。”碳不僅僅是一種膠帶，還是一種了不起的膠帶。碳將原子與原子相互聯結，形成人類、動物、植物和巖石。如果我們對碳進行加工，就能制造出塑料、顏料和各種化學制品。

2. 碳是宇宙中最豐富的元素之一。

碳位于元素周期表的頂端，在硼和氮之間。其原子序數為6，化學符號為C，有6個質子、6個中子和6個電子。碳是宇宙中第4多的元素，僅次于氫、氦和氧，地殼中則排名第15。人們認為，碳的表兄氫和氦是在宇宙大爆炸的混亂中生成的，碳則是由超新星爆炸中的α粒子堆積形成的，這個過程叫作超新星核合成。

3. 碳得名于煤。

數千年來，人們一直認為碳就是煤和煤燃燒后產生的灰燼，但1772年，安托萬·拉瓦錫證明了碳實際上是一種獨特的化學實體。拉瓦錫用直徑約4英尺的透鏡聚集太陽光線，并用名為“太陽爐”的儀器在玻璃瓶中燃燒了一顆金剛石。通過分析瓶中的殘留物，拉瓦錫得以證明金剛石完全由碳組成。拉瓦錫在其1789年出版的教科書《化學基礎論》中首次將碳列為一種化學元素。而碳這一名稱來源于法語的charbon，也就是煤。

4. 碳易成鍵。

碳原子可與其他許多元素的原子形成四個共價鍵，創造出成千上萬種化合物，其中有些正是我們日常使用的，例如塑料、藥物和汽油等。更重要的是，這些鍵既牢固又靈活。

5. 人體將近20%都是碳。

梅·尼曼是美國俄勒岡州科瓦利斯市俄勒岡州立大學的無機化學教授。她告訴《心理牙線》雜志，碳存在范圍之廣令人難以置信。尼曼說：“碳構成了所有的生命形態，生成了眾多物質，包括各種脂肪、各種糖，極為多樣。”在化學家所稱的“鏈化作用”的過程中，碳可以形成鏈和環。所有生物都是以碳為基礎構成的（碳與氮、氫、氧等元素結合）。所以，動物、植物、每個活細胞——當然也包括人類——都是鏈化作用的產物。碳占我們體重的18.5%。

不過，尼曼表示，碳也可以是無機的。碳與氧和其他物質結合在一起，可形成無生命世界中的大部分東西，如巖石和礦物。

6. 碳的兩種新形式最近幾十年才被發現。

碳目前主要有四種形式：石墨、金剛石、富勒烯和石墨烯。尼曼說：“結構決定碳的性質。”石墨（寫字石）是由片層結構的碳網松散連接在一起形成的，碳網就像鐵絲網。用鉛筆寫字實際上只是把石墨層劃到紙上。相比之下，金剛石是三維連接的。這種異常牢固的鍵只有施以巨大的能量才能打破。金剛石由于具有許多這樣的鍵，所以成為地球上最堅硬的物質。

富勒烯是在1985年發現的。當時，一群科學家用激光對石墨進行爆炸處理，生成的碳氣凝聚成了具有60和70個原子的球形分子，這是前所未知的。為紀念性格古怪的發明家巴克明斯特·富勒，這些分子以他的名字命名。富勒以發明了足球似構造的短程線穹頂聞名。羅伯特·柯爾、哈羅德·克羅托和理查德·斯莫利因發現這種新形式的碳而獲得了1996年諾貝爾化學獎。

碳家族最年輕的成員石墨烯，是安德烈·蓋姆和科斯提亞·諾沃肖洛夫2004年在一次即興研究中偶然發現的。這兩位科學家使用透明膠帶——沒錯，就是膠帶——從一塊石墨中提起厚度為一個原子的碳層。新材料極薄且堅固。結果：二位獲得了2010年諾貝爾物理學獎。

7. 金剛石被稱作“冰”并非因其外表。

金剛石被叫作“冰”，是因為它們的導熱能力使它們摸起來涼涼的，而不是因為其外表。這讓金剛石成為微芯片散熱器的理想選擇。（主要使用合成金剛石。）金剛石的三維晶格結構再次發揮作用。熱會轉變成晶格振動，這是金剛石導熱性超高的原因所在。

8. 碳有助于測定文物年代及鑒別真偽。

美國科學家威拉德·F.利比于1960年獲得諾貝爾化學獎，原因是他發明了一種通過分析文物中放射性碳同位素的數量來測定文物年代的方法。放射性碳（也叫碳-14）測年法測量的是積聚在生物中的放射性碳，即碳-14的衰變含量。這種方法甚至可以用于測量距今5萬年的物品。借助于碳測年法，人們測定了冰人奧茲的年齡，奧茲是在阿爾卑斯山發現的一具凍尸，距今已經5300年了。人們還采用這種方法確定，溫徹斯特大教堂的蘭斯洛特圓桌并非像以前認為的那樣制作于亞瑟王時代，而是亞瑟王時代數百年后的產物。

9. 碳過多正改變我們的世界。

二氧化碳是包裹著我們這個星球的大氣層的重要組成部分，使地球足夠溫暖以維持生命。但是，燃燒以碳為基架的化石燃料會釋放更多的二氧化碳，這與全球變暖直接相關。人們已經提出了許多去除和儲存二氧化碳的方法，其中包括利用碳捕捉和儲存來存儲生物能源，而這需要種植大片樹木，采伐和燃燒以產生電力，再捕捉此過程中產生的二氧化碳并將其存儲在地下。另一個正在討論的方法是人為增強海洋堿性，使之可以結合更多的二氧化碳。森林是天然的碳匯，因為樹木可通過光合作用捕捉二氧化碳，但是人類在森林中的活動抵消甚至超過了樹木對二氧化碳的捕捉。總之，我們在大氣中釋放了過量的二氧化碳，卻還沒有解決這一問題的辦法。? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?□

（譯者單位：鄭州大學）