Carbon, Chemical Element - structure, reaction, water, uses, elements, proteins, metal, gas PRONUNCIATION CAR-bun Carbon is such an important element that an entirely separate field of chemistry is devoted to this element and its compounds. Organic chemistry is the study of carbon compounds. Discovery and naming Humans have been aware of carbon since the earliest of times. When cave people made a fire, they saw smoke form. The black color of smoke is caused by unburned specks of carbon. The smoke may have collected on the ceiling of their caves as soot. Later, when lamps were invented, people used oil as a fuel. When oil burns, carbon is released in the reaction, forming a sooty covering on the inside of the lamp. That form of carbon became known as lampblack. Lampblack was also often mixed with olive oil or balsam gum to make ink. And ancient Egyptians sometimes used lampblack as eyeliner. One of the most common forms of carbon is charcoal. Charcoal is made by heating wood in the absence of air so it does not catch fire. Instead, it gives off water vapor, leaving pure carbon.

This method for producing charcoal was known as early as the Roman civilization (509 B.C.-A.D. 476). French physicist René Antoine Ferchault Reaumur (1683-1757) believed carbon might be an element. He studied the differences between wrought iron, cast iron, and steel. The main difference among these materials, he said, was the presence of a "black combustible material" that he knew was present in charcoal. Carbon was officially classified as an element near the end of the eighteenth century. In 1787, four French chemists wrote a book outlining a method for naming chemical substances. The name they used, carbone, is based on the earlier Latin term for charcoal, charbon. Coal, soot (nearly pure carbon), and diamonds are all nearly pure forms of carbon. Physical properties Carbon exists in a number of allotropic forms. Allotropes are forms of an element with different physical and chemical properties. Two allotropes of carbon have crystalline structures: diamond and graphite. In a crystalline material, atoms are arranged in a neat orderly pattern. Graphite is found in pencil "lead" and ball-bearing lubricants.

Among the non-crystalline allotropes of carbon are coal, lampblack, charcoal, carbon black, and coke. Carbon black is similar to soot. Coke is nearly pure carbon formed when coal is heated in the absence of air. Carbon allotropes that lack crystalline structure are amorphous, or without crystalline shape. The allotropes of carbon have very different chemical and physical properties. For example, diamond is the hardest natural substance known. It has a rating of 10 on the Mohs scale. The Mohs scale is a way of expressing the hardness of a material. It runs from 0 (for talc) to 10 (for diamond). The melting point of diamond is about 3,700°C (6,700°F) and its boiling point is about 4,200°C (7,600°F). Its density is 3.50 grams per cubic centimeter. On the other hand, graphite is a very soft material. It is often used as the "lead" in lead pencils. It has a hardness of 2.0 to 2.5 on the Mohs scale.

Graphite does not melt when heated, but sublimes at about 3,650°C (6.600°F). Sublimination is the process by which a solid changes directly to a gas when heated, without first changing to a liquid. Its density is about 1.5 to 1.8 grams per cubic centimeter. The numerical value for these properties varies depending on where the graphite originates. The amorphous forms of carbon, like other non-crystalline materials, do not have clear-cut melting and boiling points. Their densities vary depending on where they originate. Chemical properties Carbon does not dissolve in or react with water, acids, or most other materials. It does, however, react with oxygen. It burns in air to produce carbon dioxide (CO 2 ) and carbon monoxide (CO). The combustion (burning) of coal gave rise to the Industrial Revolution (1700-1900). Another highly important and very unusual property of carbon is its ability to form long chains. It is not unusual for two atoms of an element to combine with each other.

Oxygen (O 2 ), nitrogen (N 2 ), hydrogen (H 2 ), chlorine (Cl 2 ), and bromine (Br 2 ) are a few of the elements that can do this. Some elements can make even longer strings of atoms. Rings of six and eight sulfur atoms (S 6 and S 8 ), for example, are not unusual. Carbon has the ability to make virtually endless strings of atoms. If one could look at a molecule of almost any plastic, for example, a long chain of carbon atoms attached to each other (and to other atoms as well) would be evident. Carbon chains can be even more complicated. Some chains have side chains hanging off them. Arrangement of carbon atoms in a diamond. There is almost no limit to the size and shape of molecules that can be made with carbon atoms. (See accompanying diagrams.) Buckyballs are a recently discovered form of pure carbon. These spheres are made up of exactly 60 linked carbon atoms. Occurrence in nature Carbon is the sixth most common element in the universe and the fourth most common element in the solar system. It is the second most common element in the human body after oxygen.

About 18 percent of a person's body weight is due to carbon. The black color of smoke is caused by unburned specks of carbon. Carbon is the 17th most common element in the Earth's crust. Its abundance has been estimated to be between 180 and 270 parts per million. It rarely occurs as a diamond or graphite. Carbon reacts with oxygen by burning in air. Both allotropes are formed in the earth over millions of years, when dead plant materials are squeezed together at very high temperatures. Diamonds are usually found hundreds or thousands of feet beneath the earth's surface. Africa has many diamond mines. Carbon also occurs in a number of minerals. Among the most common of these minerals are the carbonates of calcium (CaCO 3 ) and magnesium (MgCO 3 ). Carbon also occurs in the form of carbon dioxide (CO 2 ) in the atmosphere. Carbon dioxide makes up only a small part of the atmosphere (about 300 parts per million), but it is a crucial gas. Plants use carbon dioxide in the atmosphere in the process of photosynthesis. Photosynthesis is the process by which plants convert carbon dioxide and water to carbohydrates (starches and sugars).

This process is the source of life on Earth. Carbon also occurs in coal, oil, and natural gas. These materials are often known as fossil fuels. They get that name because of the way they were formed. They are the remains of plants and animals that lived millions of years ago. When they died, they fell into water or were trapped in mud. Over millions of years, they slowly decayed. The products of that decay process were coal, oil, and natural gas. Some forms of coal are nearly pure carbon. Oil and natural gas are made primarily of hydrocarbons, which are compounds made of carbon and hydrogen. Isotopes Three isotopes of carbon occur in nature, carbon-12, carbon-13, and carbon-14. One of these isotopes, carbon-14, is radioactive. Isotopes are two or more forms of an element. Isotopes differ from each other according to their mass number. The number written to the right of the element's name is the mass number. The mass number represents the number of protons plus neutrons in the nucleus of an atom of the element.

The number of protons determines the element, but the number of neutrons in the atom of any one element can vary. Each variation is an isotope. Five artificial radioactive isotopes of carbon are known also. A radioactive isotope is one that breaks apart and gives off some form of radiation. Artificial radioactive isotopes can be made by firing very small particles (such as protons) at atoms. These particles stick in the atoms and make them radioactive. Carbon-14 has some limited applications in industry. For example, it can be used to measure the thickness of objects, such as sheets of steel. The steel must always be the same thickness. Carbon is the sixth most common element in the universe and the fourth most common element in the solar system. In this process, a small sample of carbon-14 is placed above the conveyor belt carrying the steel sheet. A detection device is placed below the sheet. The detection device counts the amount of radiation passing through the sheet. If the sheet gets thicker, Less radiation gets through. If the sheet gets thinner, more radiation gets through. The detector records how much radiation passes through the sheet. If the amount becomes too high or too low, the conveyor belt is turned off.

The machine making the sheet is adjusted to produce steel of the correct thickness. The most important use of carbon-14 is in finding the age of old objects (see accompanying sidebar for more information). Extraction Diamond, graphite, and other forms of carbon are taken directly from mines in the earth. Diamond and graphite can also be made in laboratories. Synthetic diamonds, for example, are made by placing pure carbon under very high pressures (about 800,000 pounds per square inch) and temperatures (about 2,700°C). The carbon is heated and squeezed in the same way organic material is heated and squeezed in the earth. Today, about a third of all diamonds used are synthetically produced. Carbon-14 dating W hen an organism is alive, it takes in carbon dioxide from the air around it. Most of that carbon dioxide is made of carbon-12, but a tiny portion consists of carbon-14. So the living organism always contains a very small amount of radioactive carbon, carbon-14. A detector next to the living organism would record radiation given off by the carbon-14 in the organism. When the organism dies, it no longer takes in carbon dioxide.

No new carbon-14 is added, and the old carbon-14 slowly decays into nitrogen. The amount of carbon-14 slowly decreases as time goes on. Over time, less and less radiation from carbon-14 is produced. The amount of carbon-14 radiation detected for an organism is a measure, therefore, of how long the organism has been dead. This method of determining the age of an organism is called carbon-14 dating. The decay of carbon-14 allows archaeologists (people who study old civilizations) to find the age of once-living materials. Measuring the amount of radiation remaining indicates the approximate age. Uses There are many uses for carbon's two key allotropes, diamond and graphite. Diamonds are one of the most beautiful and expensive gemstones in the world. But they also have many industrial uses. Because they are so hard they are used to polish, grind, and cut glass, metals, and other materials. The bit on an oil-drilling machine may be made of diamonds. The tool used to make thin tungsten wires is also made of diamonds. Synthetic diamonds are more commonly used in industry than in jewelry.

Industrial diamonds do not have to be free of flaws, as do jewelry diamonds. Graphite works well as pencil lead because it rubs off easily. It is also used as a lubricant. Graphite is added to the space between machine parts that rub against each other. The graphite allows the parts to slide over each other smoothly. Graphite is also used as a refractory. Refractory material can withstand very high temperatures by reflecting heat away from itself. Refractory materials are used to line ovens used to maintain high temperatures. Graphite is used in nuclear power plants. A nuclear power plant converts nuclear energy to electrical power. Graphite acts as a moderator by slowing down the neutrons used in the nuclear reaction. Graphite is used to make black paint, in explosives and matches, and in certain kinds of cathode ray tubes, like the ones used in television sets. Amorphous forms of carbon have many uses. These include the black color in inks, pigments (paints), rubber tires, stove polish, typewriter ribbons, and phonograph records. One form of carbon is known as activated charcoal. The term activated means that the charcoal has been ground into a very fine powder.

In this form, charcoal can remove impurities from liquids that pass through. For example, activated charcoal removes color and odor from oils and water solutions. The decay of carbon-14 allows archaeologists (people who study old civilizations) to find the age of once-living materials. Compounds Carbon dioxide (CO 2 ) is used to make carbonated beverages (it's the fizz in soda pop and beer), in fire extinguishers, and as a propellant in aerosol products. A propellant is a gas that pushes liquids out of a spray can, such as those used for deodorant or hair spray. Carbon dioxide can also be frozen to a solid called dry ice. It is widely used as a way of keeping objects cold. Solid carbon dioxide is most commonly known as dry ice. Carbon monoxide (CO) is another compound formed between carbon and oxygen. Carbon monoxide is a very toxic gas produced when something burns in a limited amount of air. Carbon monoxide is always formed when gasoline burns in the engine of an automobile and is a common part of air pollution. Old heating units can produce carbon monoxide. This colorless and odorless gas can cause headaches, illness, coma, or even death.

Carbon monoxide has a few important industrial uses. It is often used to obtain a pure metal from the ore of that metal: It would take a very large book to describe all the uses of organic compounds, which are divided into a number of families. An organic family is a group of organic compounds with similar structures and properties. The largest organic family is the hydrocarbons, compounds that contain only carbon and hydrogen. Methane, or natural gas (CH 4 ), ethane (C 2 H 6 ), propane (C 3 H 8 ), ethylene (C 2 H 4 ), and benzene (C 6 H 6 ) are all hydrocarbons. Hydrocarbons are used as fuels. Gas stoves burn natural gas, which is mostly methane. Propane gas is a popular camping fuel, used in small stoves and lanterns. Another important use of hydrocarbons is in the production of more complicated organic compounds. Buckyballs and nanotubes In the 1980s, chemists discovered a new allotrope of carbon. The carbon atoms in this allotrope are arranged in a sphere-like form of 60 atoms.

The form resembles a building invented by American architect Buckminster Fuller (1895-1983). The building is known as a geodesic dome. Each of the points on the dome is occupied by one carbon atom. The discoverers named the new form of carbon buckminsterfullerene in honor of Fuller. That name is too long to use in everyday conversation so it is usually shortened to fullerene or buckyball. The discovery of the fullerene molecule was very exciting to chemists. They had never seen a molecule like it. They have been studying ways of working with this molecule. One interesting technique has been to cut open just one small part of the molecule. Then they cut open a small part on a second molecule. Finally, they join the two buckyballs together. They get a double-buckyball. Repeating this process over and over could result in triple-buckyballs, quadruple-buckyballs, and so on. As this process is repeated, the buckyball becomes a long narrow tube called a nanotube. Nanotubes are long, thin, and extremely tiny tubes somewhat like a drinking straw or a long piece of spaghetti. Scientists are beginning to find ways of using nanotubes.

One idea is to run a thin chain of metal atoms through the center of a nanotube. This allows it to act like a tiny electrical wire. Nanotubes may completely change many devices that will be made in the future. Other organic families contain carbon, hydrogen, and oxygen. Methyl alcohol (wood alcohol) and ethyl alcohol (grain alcohol) are the most common members of the alcohol family. Methyl alcohol is used to make other organic compounds and as a solvent (a substance that dissolves other substances). Ethyl alcohol is used for many of the same purposes. It is also the alcohol found in beer, wine, and hard liquor, such as whiskey and vodka. All alcohols are poisonous but some alcohols are more poisonous than others. If not drunk in moderation, alcoholic beverages can damage the body and brain. And, if drunk in large quantities, they can cause death. Methyl alcohol is more toxic than ethyl alcohol. People who have drunk methyl alcohol by mistake have died. The list of everyday products made from organic compounds is very long.

It includes drugs, artificial fibers, dyes, artificial colors and flavors, food additives, cosmetics, plastics of all kinds, detergents, synthetic rubber, adhesives, antifreeze, pesticides and herbicides, synthetic fuels, and refrigerants. Health effects Carbon is essential to life. Nearly every molecule in a living organism contains carbon. The study of carbon compounds that occur in living organisms is called biochemistry (bio- = life + -chemistry ). Carbon can also have harmful effects on organisms. For example, coal miners sometimes develop a disease known as black lung. The name comes from the appearance of the miner's lungs. Instead of being pink and healthy, the miner's lungs are black. The black color is caused by coal dust inhaled by the miner. The longer a miner works digging coal, the more the coal dust is inhaled. That worker's lungs become more and more black. Color is not the problem with black lung disease however. The coal dust in the lungs blocks the tiny holes through which oxygen gets into the lungs. As more coal dust accumulates, more holes are plugged up, making it harder for the miner to breathe. Many miners eventually die from black lung disease because they lose the ability to breathe. Carbon is essential to life.

Nearly every molecule in a living organism contains carbon. Carbon monoxide poisoning is another serious health problem. Carbon monoxide is formed whenever coal, oil, or natural gas bums. For example, the burning of gasoline in cars and trucks produces carbon monoxide. Today, almost every person in the United States inhales some carbon monoxide every day. Small amounts of carbon monoxide are not very dangerous. But larger amounts cause a variety of health problems. At low levels, carbon monoxide causes headaches, dizziness, nausea, and loss of balance. At higher levels, a person can lose consciousness. At even higher levels, carbon monoxide can cause death. Also read article about Carbon from Wikipedia User Contributions: named by Antoine Lavoisier in 1772 History & Etymology Carbon is of prehistoric knowledge as diamond as well as graphite. That diamonds were known at least as early as 1200 B.C. seems probable according to ancient Hindu writings. The earliest authentic reference to the diamond is ascribed to one Manilius near the 1st century AD.

The name diamond derives from a corruption of the Greek word "adamas" (the invincible) (Or: from the Latin adámas, adámantis, which is itself a Greek word, adamas, adamantos, meaning in these languages "hard steel"). The first recognition of graphite is obscured in antiquity. It was confused with other minerals of similar appearance, chiefly molydenite (MoS2). One name for graphite is "plumbago", like lead; and until modern times it was thought to contain lead. Also carbon in the forms of charcoal and soot must have been known to the earliest humans. In Roman times charcoal was made by the same chemistry as it is today, by heating wood in a pyramid covered with clay to exclude air. The woodcut shows two stages in the manufacture of wood charcoal. In 1704 Sir Isaac Newton (1642-1727) proposed that diamonds must be combustible. In 1772 Antoine Lavoisier (1743-1794) demonstrated that charcoal, graphite, and diamond contain the same substance. Lavoisier called the element carbone to distinguish it from "charbon" (French) for charcoal.

Carl Wilhelm Scheele (1742-1786), in 1779, demonstrated that graphite oxidized to carbon dioxide providing its chemical constitution. The name graphite, which comes from the Greek verb γραφειν [graphein], to write, originated with Werner in 1789. Translations Also in several other languages the name of the element is derived from the native name for coal or charcoal: German: Kohl = coal, and Stoff = material. Dutch: kool = coal, and stof = material. Czech: uhel = coal. Magnesium - Element information, properties and uses | Periodic Table Chemistry in its element: magnesium (Promo) You're listening to Chemistry in its element brought to you by Chemistry World, the magazine of the Royal Society of Chemistry (End promo) Chris Smith Hello, this week we meet the substance whose chemical claim to fame is that its quite literally hit a bum note in the past as a cure for constipation. But its explosive role isn't just confined to the colon because it's also the basis of incendriary bombs and even the existence of life on earth.

And to tell the story of Magnesium, here's John Emsley. John Emsley It was once the destroyer of cities - now it's a saver of energy The summer of 1618 saw England gripped by drought, but as Henry Wicker walked across Epsom Common he was came across a pool of water from which thirsty cattle refused to drink. He found that the water tasted bitter and on evaporation it yielded a salt which had a remarkable effect: it acted as a laxative. This became the famous Epsom's salt (magnesium sulfate, MgSO4) and became a treatment for constipation for the next 350 years. The first person to propose that magnesium was an element was Joseph Black of Edinburgh in 1755, and an impure form of metallic magnesium was produced in 1792 by Anton Rupprecht who heated magnesia (magnesium oxide, MgO) with charcoal. He named the element austrium after his native Austria.

A small sample of the pure metal was isolated by Humphry Davy in 1808, by the electrolysis of moist MgO, and he proposed the name magnium based on the mineral magnesite (MgCO3) which came from Magnesia in Greece. Neither name survived and eventually it was called magnesium. Magnesium is essential to almost all life on Earth - it is at the heart of the chlorophyll molecule, which plants use to convert carbon dioxide into glucose, and then to cellulose, starch, and many other molecules which pass along the food chain. Humans take in around 300 mg of magnesium per day and we need at least 200 mg, but the body has a store of around 25 g of this element in its skeleton so there is rarely a deficiency. Almonds, brazil nuts, cashew nuts, soybeans, parsnips, bran, and even chocolate are all rich in magnesium. Some brands of beer contain a lot, such as Webster's Yorkshire Bitter - it may owe some of its flavour to the high levels of magnesium sulfate in the water used to brew it.

Magnesium is the seventh most abundant element in the Earth's crust, and third most abundant if the Earth's mantle is also taken into consideration because this consists largely of olivine and pyroxene, which are magnesium silicates. It is also abundant in sea water (1200 p.p.m.) so much so that this was the source of magnesium for bombs in World War II. The metal itself was produced by the electrolysis of the molten chloride. Once magnesium starts to burn it is almost impossible to extinguish, because it reacts exothermically with oxygen, nitrogen and water. It burns with a bright light and was used for photographic flash bulbs It made an ideal incendiary agent and in some air raids during World War II as many as half a million 2 kg magnesium bombs would be scattered over a city in the space of an hour. The result was massive conflagrations and firestorms. Bulk magnesium metal is not easily ignited so this had to be done by a thermite reaction at the heart of the bomb. The thermite reaction, between aluminium powder and iron oxide, releases more than enough heat to cause the magnesium casing of the bomb to burn fiercely.

Many minerals are known which contain magnesium; but the main ones are dolomite (calcium magnesium carbonate, CaMg(CO3)2) and magnesite which are mined to the extent of 10 million tonnes per year. Magnesite is heated to convert it to magnesia (MgO), and this has several applications: fertilizers; cattle feed supplement; a bulking agent in plastics; and for heat-resistant bricks for fireplaces and furnaces. The metal itself is being produced in increasing amounts. It was originally introduced for racing bicycles which were the first vehicles to use pure magnesium frames, giving a better combination of strength and lightness than other metals. (A steel frame is nearly five times heavier than a magnesium one.) For use as a metal, magnesium is alloyed with a few percent of aluminium, plus traces of zinc and manganese, to improve strength, corrosion resistance and welding qualities, and this alloy is used to save energy by making things lighter. It is found in car and aircraft seats, lightweight luggage, lawn mowers, power tools, disc drives and cameras. At the end of its useful life the magnesium in all these products can be recycled at very little cost.

Because it is an electropositive metal, magnesium can be act as a 'sacrificial' electrode to protect iron and steel structures because it corrodes away preferentially when they are exposed to water which otherwise would cause rusting Chris Smith So better bikes, better bombs and better bums. Thank you very much to science writer John Emsley for telling the tale of Magnesium. Next week the illuminating story of the element that spawned a light bulb but really needs to work on its image. Quentin Cooper If any element needs a change of PR this is the one. It's brittle, prone to ponginess and arguably the dunce of the periodic table. Even the man who discovered osmium treated it rather sniffily. It reeked - or at least some of its compounds did. Tennant described the "pungent and penetrating smell" as one of the new element's "most distinguishing characters". So he called it osmium - osme being the Greek for odour. Chris Smith That's Quentin Cooper who will be undressing osmium for us in next week's Chemistry in its element, I hope you can join us. I'm Chris Smith, thank you for listening, see you next time.

(Promo) Chemistry in its element is brought to you by the Royal Society of Chemistry and produced by thenakedscientists.com . There's more information and other episodes of Chemistry in its element on our website at chemistryworld.org/elements . (End promo) Carbon - Element information, properties and uses | Periodic Table Chemistry in its element: carbon (Promo) You're listening to Chemistry in its element brought to you by Chemistry World, the magazine of the Royal Society of Chemistry. (End promo) Chris Smith Hello, this week to the element that unites weddings, wars, conflicts and cremations and to explain how, here's Katherine Holt. Katherine Holt Any chemist could talk for days about carbon. It is after all an everyday, run-of-the-mill, found-in-pretty-much-everything, ubiquitous element for us carbon-based life forms. An entire branch of chemistry is devoted to its reactions. In its elemental form it throws up some surprises in the contrasting and fascinating forms of its allotropes. It seems that every few years a new form of carbon comes into fashion - A few years ago carbon nanotubes were the new black (or should I say 'the new bucky-ball') - but graphene is oh-so-now!

But today I'm going to talk about the most glamorous form that carbon can take - diamond. For millennia diamond has been associated with wealth and riches, as it can be cut to form gemstones of high clarity, brilliance and permanence. Diamonds truly are forever! Unfortunately, diamond also has a dark side - the greed that diamond induces leads to the trade of so-called 'conflict diamonds' that support and fund civil wars. Mans desire for diamond has led alchemists and chemists over many centuries to attempt to synthesise the material. After many fraudulous early claims diamond was finally synthesised artificially in the 1950s. Scientists took their inspiration from nature by noting the conditions under which diamond is formed naturally, deep under the earth's crust. They therefore used high temperatures (over 3000oC) and high pressures (>130 atms) to turn graphite into carbon. This was an impressive feat, but the extreme conditions required made it prohibitively expensive as a commercial process. Since then the process has been refined and the use of metal catalysts means that lower temperatures and pressures are required.

Crystals of a few micron diameter can be formed in a few minutes, but a 2-carat gem quality crystal may takes several weeks. These techniques mean its now possible to artificially synthesise gemstone quality diamonds which, without the help of specialist equipment, cannot be distinguished from natural diamond. It goes without saying that this could cause headaches among the companies that trade in natural diamond! It is possible to turn any carbon based material into a diamond - including hair and even cremating remains! Yes - you can turn your dearly departed pet into a diamond to keep forever if you want to! Artificial diamonds are chemically and physical identical to the natural stones and come without the ethical baggage. However, psychologically their remains a barrier - if he really loves you he'd buy you real diamond - wouldn't he? From the perspective of a chemist, materials scientist or engineer we soon run out of superlatives while describing the amazing physical, electronic and chemical properties of diamond. It is the hardest material known to man and more or less inert - able to withstand the strongest and most corrosive of acids. It has the highest thermal conductivity of any material, so is excellent at dissipating heat. That is why diamonds are always cold to the touch.

Having a wide band gap, it is the text book example of an insulating material and for the same reason has amazing transparency and optical properties over the widest range of wavelengths of any solid material. You can see then why diamond is exciting to scientists. Its hardness and inert nature suggest applications as protective coatings against abrasion, chemical corrosion and radiation damage. Its high thermal conductivity and electrical insulation cry out for uses in high powered electronics. Its optical properties are ideal for windows and lenses and its biocompatibility could be exploited in coatings for implants. These properties have been known for centuries - so why then is the use of diamond not more widespread? The reason is that natural diamond and diamonds formed by high pressure high temperature synthesis are of limited size - usually a few millimeters at most, and can only be cut and shaped along specific crystal faces. This prevents the use of diamond in most of the suggested applications. However, about 20 years ago scientists discovered a new way to synthesise diamond this time under low pressure, high temperature conditions, using chemical vapour deposition. If one were to consider the thermodynamic stability of carbon, we would find that at room temperature and pressure the most stable form of carbon is actually graphite, not diamond.

Strictly speaking, from a purely energetic or thermodynamic point of view, diamond should spontaneously turn into graphite under ambient conditions! Clearly this doesn't happen and that is because the energy required to break the strong bonds in diamond and rearrange them to form graphite requires a large input of energy and so the whole process is so slow that on the scale of millennia the reaction does not take place. It is this metastability of diamond that is exploited in chemical vapour deposition. A gas mixture of 99 % hydrogen and 1 % of methane is used and some activation source like a hot filament employed to produce highly reactive hydrogen and methyl radicals. The carbon-based molecules then deposit on a surface to form a coating or thin film of diamond. Actually both graphite and diamond are initially formed, but under these highly reactive conditions, the graphitic deposits are etched off the surface, leaving only the diamond. The films are polycrystalline, consisting of crystallites in the micron size range so lack the clarity and brilliance of gemstone diamond. While they may not be as pretty, these diamond films can be deposited on a range of surfaces of different size and shapes and so hugely increase the potential applications of diamond.

Challenges still remain to understand the complex chemistry of the intercrystalline boundaries and surface chemistry of the films and to learn how best to exploit them. This material will be keeping chemists, materials scientists, physicists and engineers busy for many years to come. However, at present we can all agree that there is more to diamond than just a pretty face! Chris Smith Katherine Holt extolling the virtues of the jewel in carbon's crown. Next week we're heading to the top of group one to hear the story of the metal that revolutionised the treatment of manic depression. Matt Wilkinson Its calming effect on the brain was first noted in 1949, by an Australian doctor, John Cade, of the Victoria Department of Mental Hygiene. He had injected guinea pigs with a 0.5% solution of lithium carbonate, and to his surprise these normally highly-strung animals became docile. Cade then gave his most mentally disturbed patient an injection of the same solution. The man responded so well that within days he was transferred to a normal hospital ward and was soon back at work. Chris Smith And it's still used today although despite 50 years of medical progress we still don't know how it works.

That was Matt Wilkinson who will be here with the story of Lithium on next week's Chemistry in its Element, I do hope you can join us. I'm Chris Smith, thank you for listening and goodbye. (Promo) Chemistry in its element is brought to you by the Royal Society of Chemistry and produced by thenakedscientists.com . There's more information and other episodes of Chemistry in its element on our website at chemistryworld.org/elements . (End promo) Carbon - expert written, user friendly element information Appearance and Characteristics Harmful effects: Pure carbon has very low toxicity. Inhalation of large quantities of carbon black dust (soot/coal dust) can cause irritation and damage to the lungs. Characteristics: Carbon can exist with several different 3 dimensional structures in which its atoms are arranged differently (allotropes). Three common crystalline allotropes are graphite, diamond, and (usually) fullerenes. Graphene has a 2D crystal structure.(Fullerenes can sometimes exist in amorphous form.)(9) Carbon can also exist in an amorphous state.

Many allotropes commonly described as amorphous, however, such as glassy carbon, soot, or carbon black usually have enough structure to not be truly amorphous. Although crystalline nanotubes have been observed, they are generally amorphous.(10) The structures of eight allotropes are shown at the bottom of this page. Interestingly, graphite is one of the softest substances and diamond was thought, until recently, to be the hardest naturally occurring substance. An extremely rare allotrope of carbon, lonsdaleite, has been calculated, in pure form, to be 58% stronger than diamond. Lonsdaleite is a diamond-like carbon network which has graphite’s hexagonal structure. It is made when meteorites containing graphite hit another body, such as Earth. The high temperatures and pressures of the impact transform the graphite into lonsdaleite. Carbon has the highest melting/sublimation point of all the elements and, in the form of diamond, has the highest thermal conductivity of any element. Diamond’s high thermal conductivity is the origin of the slang term ‘ice.’ At typical room temperatures your body temperature is higher than the room’s – including any large diamonds you may just happen to have lying around.

If you touch any of these diamonds, their high thermal conductivity carries heat away from your skin faster than any other material. Your brain interprets this rapid transfer of heat energy away from your skin as meaning you are touching something very cold – so diamonds at room temperature can feel like ice. Uses of Carbon Carbon (in the form of coal, which is mainly carbon) is used as a fuel. Graphite is used for pencil tips, high temperature crucibles, dry cells, electrodes and as a lubricant. Diamonds are used in jewelry and – because they are so hard – in industry for cutting, drilling, grinding, and polishing. Carbon black is used as the black pigment in printing ink. Carbon can form alloys with iron , of which the most common is carbon steel. The 14C radioactive isotope is used in archaeological dating. Carbon compounds are important in many areas of the chemical industry – carbon forms a vast number of compounds with hydrogen , oxygen , nitrogen and other elements.

Abundance and Isotopes Abundance earth’s crust: 200 parts per million by weight, 344 parts per million by moles Abundance solar system: 3000 parts per million by weight, 300 parts per million by moles Cost, pure: $2.4 per 100g Cost, bulk: $ per 100g Source: Carbon can be obtained by burning organic compounds with insufficient oxygen. The four main allotropes of carbon are graphite, diamond, amorphous carbon and fullerenes. Natural diamonds are found in kimberlite from ancient volcanoes. Graphite can also be found in natural deposits. Fullerenes were discovered as byproducts of molecular beam experiments in the 1980s. Amorphous carbon is the main constituent of charcoal, soot (carbon black), and activated carbon. Isotopes: 13 whose half-lives are known, with mass numbers 8 to 20. Naturally occurring carbon is a mixture of two isotopes and they are found in the percentages shown: 12C (99%) and 13C (1%).

Isotope 14C, with a half-life of 5730 years, is widely used to date carbonaceous materials such as wood, archeological specimens, etc. for ages up to about 40 000 years. References 1. Robert E. Krebs, The history and use of our earth’s chemical elements: a reference guide., (2006) p192. Greenwood Publishing Group 2. Mary Elvira Weeks, The discovery of the elements. I. Elements known to the ancient world., J. Chem. Educ., 1932, 9 (1), p4 3. Jessica Elzea Kogel, Industrial minerals & rocks: commodities, markets, and uses., (2006) p507. SME. 4. Amanda S. Barnard, The diamond formula: diamond synthesis–a gemological perspective., (2000) p3. Butterworth-Heinemann 5. Robert M. Hazen, The diamond makers., (1999) p145. Cambridge University Press. 6. Jonathan W. Steed, Jerry L.

Atwood, Supramolecular Chemistry., (2009) p423. Wiley. 8. What do we need to make a tire? 9. Ming Gao and Hui Zhang, Preparation of an amorphous fullerene film ., Physics Letters A Volume 213, Issues 3-4, 22 April 1996, Pages 203-206 10. Ron Dagani, Nanotube Magic , Materials Research , April 16, 2001 Volume 79, Number 16 CENEAR 79 16 pp.6. Cite this Page For online linking, please copy and paste one of the following: <a href="">Carbon</a> or <a href="">Carbon Element Facts</a> To cite this page in an academic document, please use the following MLA compliant citation: "Carbon." Chemicool Periodic Table. Chemicool.com. 25 July. 2014. Web.

< carbon group element | chemical elements | Britannica.com Carbon group element Alternative Titles: Group 14 element, Group IVa element Related Topics Carbon group element, any of the six chemical elements that make up Group 14 (IVa) of the periodic table—namely, carbon (C), silicon (Si), germanium (Ge), tin (Sn), lead (Pb), and flerovium (Fl). Modern version of the periodic table of the elements. Encyclopædia Britannica, Inc. Except for germanium and the artificially produced flerovium, all of these elements are familiar in daily life either as the pure element or in the form of compounds , although, except for silicon, none is particularly plentiful in the Earth’s crust. Carbon forms an almost infinite variety of compounds, in both the plant and animal kingdoms. Silicon and silicate minerals are fundamental components of the Earth’s crust; silica (silicon dioxide) is sand. Tin and lead, with abundances in the crust lower than those of some so-called rare elements, are nevertheless common in everyday life.

They occur in highly concentrated mineral deposits, can be obtained easily in the metallic state from those minerals, and are useful as metals and as alloys in many applications. Germanium, on the other hand, forms few characteristic minerals and is most commonly found only in small concentrations in association with the mineral zinc blende and in coals. Although germanium is indeed one of the rarer elements, it assumed importance upon recognition of its properties as a semiconductor (i.e., limited ability to conduct electricity). Comparative chemistry In the periodic table , the elements with eight electrons outermost form the group known as the noble gases (Group 18 [0]), the least reactive of the elements. The carbon group elements (Group 14), with four electrons, occupy a middle position. Elements to the left of Group 14 have fewer than four electrons in the valence shell and tend to lose them (with their negative charges) to become positively charged ions, represented by the symbol for the element with a superscript indicating the number and sign of the charges; such elements are called metals.

The nonmetals (except boron) are in the groups to the right of Group 14; each has more than four electrons in its outermost shell and tends to acquire electrons to complete its octet, forming negatively charged ions. Similar Topics osmium (Os) Chemical reactions result from the exchange of electrons among atoms. In general, if a metal loses its few valence electrons to a nonmetal, the resulting oppositely charged ions are attracted to one another and form a bond, classified as ionic or electrovalent. Two nonmetals, neither of which can actually lose its valence electrons in chemical reaction, may nevertheless share them in pairs in such a way that what is called a covalent bond results. Metal atoms will bond to one another in a third type of bond, which releases their valence electrons in a way that allows them to conduct electricity. All the carbon group atoms, having four valence electrons, form covalent bonds with nonmetal atoms; carbon and silicon cannot lose or gain electrons to form free ions, whereas germanium, tin, and lead do form metallic ions but only with two positive charges.

Even lead, the most metallic of the carbon group atoms, cannot actually lose all four of its valence electrons, because, as each one is removed, the remainder are held more strongly by the increased positive charge. Because the distinction between covalent and ionic (electrovalent) bonds is often a matter of convenience for the chemist, and because the actual bond structure within a molecule may be quite complicated, it is often useful instead simply to count the total number of electrons an element gains or loses in bonding without regard to the nature of the bonds. This number is called the oxidation number , or oxidation state, of the element; many elements have more than one oxidation state possible, each oxidation state being found in different compounds. The oxidation state of an element is conventionally written as a Roman numeral following the name of the element in a compound—for example, lead(II) means lead in the +2 oxidation state. An alternative system of representation uses an Arabic number after the element name; thus, lead in the +2 state is written lead(+2). With the chemical symbol of the element, the oxidation state may be written as a superscript, as in Pb2+.

When the compounds are ionic, the oxidation state is also the actual ionic charge. Covalent bonds generally are considered to be formed by interaction of the orbitals (in most cases, only the s, p, and d orbitals) in specific and varied ways. The most common are called sigma and pi bonds, written σ and π, respectively. The sigma bonds are symmetrical with respect to the axis of the bond, whereas the pi bonds are not. Examples of sigma and pi bonding as well as of ionic bonding can be found among the compounds of the elements of the carbon group. General properties of the group Britannica Stories Ringling Bros. Folds Its Tent The properties of the carbon group elements and those of their compounds are intermediate between properties associated with the elements of the adjacent boron and nitrogen groups. In all groups the metallic properties, resulting from the tendency to hold valence electrons more loosely, increase with atomic number . Within the carbon group, more than in any other, the change from nonmetallic to metallic character with increasing atomic number is particularly apparent. Carbon is a true nonmetal in every sense. Lead is a true metal. Silicon is almost completely nonmetallic; tin is almost completely metallic.

Germanium is metallic in appearance and in a number of its other physical properties (see Table), but the properties of many of its compounds are those of derivatives of nonmetals. These changes are consequences of increase in atomic size with substantial screening of the larger nuclear charge by intervening electronic shells, as evidenced by decrease in ionization energy (energy required to remove an electron) and electronegativity power to attract electrons with increasing atomic number.

Some properties of the carbon group elements carbon density (grams per cubic centimetre) 1.9–2.3 (graphite), 3.15–3.53 (diamond) 2.33 (25 °C) mass number of most common isotopes (terrestrial abundance, percent) 12 (98.89), 13 (1.11) 28 (92.23), 29 (4.68), 30 (3.09) radioactive isotopes (mass numbers) heat of fusion (calories per mole/kilojoules per mole) 25,100 (105) heat of vaporization (kilojoules per mole) 715 heat of sublimation (kilocalories per gram atom) 170 heat capacity (joules per gram Kelvin) 0.709 ionization energy (kilojoules per mole) first white metallic (beta), gray (alpha) bluish white metallic density (grams per cubic centimetre) 5.32 (25 °C) mass number of most common isotopes (terrestrial abundance

, percent) 70 (20.84), 72 (27.54), 73 (7.73), 74 (36.28), 76 (7.61) 112 (0.97), 114 (0.66), 115 (0.34), 116 (14.54), 117 (7.68), 118 (24.22), 119 (8.59), 120 (32.58), 122 (4.63), 124 (5.79) 204 (1.4), 206 (24.1), 207 (22.1), 208 (52.4) radioactive isotopes (mass numbers) 60–69, 71, 75–89 100–111, 113, 121, 123, 125–137 181–20

5, 209–215 heat of fusion (calories per mole/kilojoules per mole) 7,600 (31.8) heat of vaporization (kilojoules per mole) 334 heat of sublimation (kilocalories per gram atom) — heat capacity (joules per gram Kelvin) 0.32 ionization energy (kilojoules per mole) first Periodic Table of the Elements In the solid state, elemental carbon, silicon, germanium, and gray tin (defined as alpha [α] tin) exist as cubic crystals, based upon a three-dimensional arrangement of bonds.

Each atom is covalently bonded to four neighbouring atoms in such a way that they form the corners of a tetrahedron (a solid consisting of four three-sided faces). A practical result is that no discrete small molecules of these elements, such as those formed by nitrogen, phosphorus , or arsenic , can be distinguished; instead, any solid particle or fragment of one of these elements, irrespective of size, is uniformly bonded throughout, and, therefore, the whole fragment can be considered as a giant molecule. Decreasing melting points , boiling points , and decreasing heat energies associated with fusion (melting), sublimation (change from solid to gas), and vaporization (change from liquid to gas) among these four elements, with increasing atomic number and atomic size, indicate a parallel weakening of the covalent bonds in this type of structure. The actual or probable arrangement of valence electrons is often impossible to determine, and, instead, relative energy states of the electrons, in the ground, or least energetic, state of the atom are considered. Thus, the same trend of nonmetallic toward metallic states is indicated by decreasing hardness and decreasing single-bond energy between atoms.

Carbon crystallizes in two forms, as diamond and as graphite; diamond stands apart from all other elemental forms in the extreme stability of its crystal structure, whereas graphite has a layer structure. As may be expected, cleavage between layers of graphite is much easier to effect than rupture within a layer. The crystal structures of white beta (β) tin and elemental lead are clearly metallic structures. In a metal, the valence electrons are free to move from atom to atom, and they give the metal its electrical conductivity. Electron configurations Facebook Twitter YouTube Instagram Pinterest The ground-state electronic configurations of atoms of these carbon group elements show that each has four electrons in its outermost shells. As has been explained, if n represents the outermost shell (n being two for carbon, three for silicon, etc.), then these four electrons are represented by the symbols ns2np2. Such a configuration suggests the importance of referring to the relatively stable noble-gas-atom configuration preceding each element in determining the properties of the element, in particular its chemical properties.

The loss of four electrons by either a carbon atom or a silicon atom to give ions having a positive charge of four (or +4, written C4+ or Si4+) with the electron configurations of the preceding noble-gas atoms is precluded by the sizable ionization energies. Ions of +4 charge do not exist, nor is there any evidence that carbon or silicon ions of charge +2 can form by the loss of only two unpaired (np, or outermost) electrons. Electron loss by atoms of the heavier elements of the family is easier, but it cannot lead to ions with noble-gas-atom configurations because of the presence of underlying (i.e., d10) arrangements of electrons inside the outermost shell. It is again unlikely that the +4 ions of germanium, tin, and lead (in symbols Ge4+, Sn4+, and Pb4+) exist in known compounds, but it is true that the inertness of the ns2 pair of electrons (which are, in terms of energy states, closer to the nucleus than the np2 pair) increases substantially with increasing atomic number in the family and thus allows the np2 electrons to be removed separately, to form at least the ions, Sn2+ and Pb2+.

Oxidation states of +2 and +4 can be assigned in covalent compounds of each of these elements with elements that are more electronegative (i.e., having greater affinity for electrons). Catenation Editor Picks: Exploring 10 Types of Basketball Movies Carbon is unique among the elements in the almost infinite capacity of its atoms to bond to each other in long chains, a process called catenation (Latin catena, chain). This characteristic reflects the strength of the bond between adjacent carbon atoms in the molecule, both in relationship to similar bonds involving other elements of the carbon family and in relationship to bonds between carbon atoms and atoms of many other elements. Only the carbon–hydrogen, carbon–fluorine, and carbon–oxygen single bonds (C−H, C−F, and C−O) are stronger than the carbon–carbon single bond (C−C), and each of these is weaker than the carbon–carbon multiple bonds (C=C or C≡C). On the other hand, the silicon–silicon single bond (Si−Si) is weaker than other single bonds involving an atom of other elements with the silicon atom.

The same is undoubtedly true of the germanium–germanium and tin–tin single bonds (Ge−Ge, Sn−Sn) in relationship to single covalent bonds between atoms of these elements and atoms of other elements. Experimentally, there appears to be no practical upper limit to catenation involving carbon. This phenomenon in three dimensions produces the diamond and in two dimensions the layers in graphite. Catenation is also exhibited to a high degree by elemental silicon, germanium, and tin, but it is strictly limited in compounds of these elements; silicon may have up to 14 atoms in a chain; germanium, 9; and tin, 2 or 3 only, largely in hydrides (compounds containing hydrogen). Double and triple bonds in catenated arrangements are limited to carbon. Trending Topics Eyjafjallajökull volcano Catenation, via single or multiple bonds or both, combined with several other factors allows carbon to form more compounds than any other element.

These factors are: (1) the stability of certain carbon bonds, in particular of the C−H bond; (2) the existence of carbon in both sp2 and sp3 hybridizations; (3) the ability of carbon to form both chain and cyclic compounds (in which the chain of atoms is joined end to end to form a ring) based upon either carbon atoms alone or carbon atoms in combination with those of other nonmetals (e.g., oxygen , sulfur , nitrogen) and either upon single- or multiple-bond arrangements; and (4) the capability of many carbon compounds to exist in isomeric forms (isomers are molecules with identical numbers of the same atoms bonded in different arrangements; such molecules have quite different properties). All but a very few carbon compounds are called organic compounds, and they are discussed in the article chemical compound . Atomic size Reference has been made to some of the physical properties of the carbon group elements. Most of the variations in properties from carbon through lead parallel increase in atomic size and are comparable with those of elements in the boron, nitrogen, oxygen, and fluorine groups. The general trends are roughly those found for the adjacent boron group and nitrogen group elements.

The significantly higher melting and boiling points of the carbon group elements reflect their tendency to exist as giant molecules, as opposed to the tendencies of elements in the adjacent families to exist as smaller, discrete molecules. As is true of the lightest element in each group of elements, the physical properties of carbon differ substantially from those of the other members of its family. To a large degree, these differences reflect the substantially higher concentration of the positive charge on the carbon nucleus relative to the size of the carbon atom. That is, the nucleus of carbon holds only six electrons in two shells and, therefore, holds them close; the nucleus of lead, on the other hand, has 82 electrons distributed in six shells. The attraction between the nucleus of lead and its outermost electrons is less than in carbon, because intervening shells in lead shield the outer electrons. Structural differences between diamond and graphite produce profound differences between them in hardness, conductivity, density , heat capacity, and other properties. Inasmuch as graphite is a unique crystalline formation among the elements, its properties should not be compared directly with those of the other elements in the family.

Reactions With a given reagent, diamond is generally less reactive than graphite and, thus, requires more rigorous conditions for reaction, such as a higher temperature; the ultimate products, however, are the same. Crystalline silicon is less reactive than finely divided and, possibly, amorphous silicon. Elemental germanium resembles silicon quite closely. Tin and lead behave in general as metals and thus yield at least some ionic products in reactions that are quite different from those of the other elements. Elemental carbon is of particular importance as a high-temperature reducing agent (a reagent that donates electrons) in metallurgical processing for metal oxides, a reaction that frees the metal. For example, tin can be obtained from its ore cassiterite by reduction with carbon in the form of charcoal . Thus to cite only a few of carbon’s more important applications, carbon is used directly in the production of elemental phosphorus, arsenic, bismuth , tin, lead, zinc, and cadmium , and indirectly, as carbon monoxide , in the production of iron . Elemental silicon, in the iron–silicon alloy ferrosilicon, is also a strong reducing agent and has been used as such to liberate magnesium from its oxide.

Question: What chemical element is named from the French for charcoal?
Answer: Carbon