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Jump to main content. Periodic Table. Glossary Allotropes Some elements exist in several different structural forms, called allotropes. Glossary Group A vertical column in the periodic table. Fact box. Glossary Image explanation Murray Robertson is the artist behind the images which make up Visual Elements. Appearance The description of the element in its natural form. Biological role The role of the element in humans, animals and plants.
Natural abundance Where the element is most commonly found in nature, and how it is sourced commercially. Uses and properties. Image explanation. There are a number of pure forms of this element including graphite, diamond, fullerenes and graphene. Diamond is a colourless, transparent, crystalline solid and the hardest known material.
Graphite is black and shiny but soft. The nano-forms, fullerenes and graphene, appear as black or dark brown, soot-like powders. Carbon is unique among the elements in its ability to form strongly bonded chains, sealed off by hydrogen atoms.
These hydrocarbons, extracted naturally as fossil fuels coal, oil and natural gas , are mostly used as fuels. A small but important fraction is used as a feedstock for the petrochemical industries producing polymers, fibres, paints, solvents and plastics etc.
Impure carbon in the form of charcoal from wood and coke from coal is used in metal smelting. It is particularly important in the iron and steel industries. Graphite is used in pencils, to make brushes in electric motors and in furnace linings. Activated charcoal is used for purification and filtration. It is found in respirators and kitchen extractor hoods. Carbon fibre is finding many uses as a very strong, yet lightweight, material. It is currently used in tennis rackets, skis, fishing rods, rockets and aeroplanes.
Industrial diamonds are used for cutting rocks and drilling. Diamond films are used to protect surfaces such as razor blades. The more recent discovery of carbon nanotubes, other fullerenes and atom-thin sheets of graphene has revolutionised hardware developments in the electronics industry and in nanotechnology generally. In , as a result of combusting fossil fuels with oxygen, there was ppm. Atmospheric carbon dioxide allows visible light in but prevents some infrared escaping the natural greenhouse effect.
This keeps the Earth warm enough to sustain life. However, an enhanced greenhouse effect is underway, due to a human-induced rise in atmospheric carbon dioxide. This is affecting living things as our climate changes. Biological role. Carbon is essential to life. This is because it is able to form a huge variety of chains of different lengths.
It was once thought that the carbon-based molecules of life could only be obtained from living things. However, in , urea was synthesised from inorganic reagents and the branches of organic and inorganic chemistry were united. Living things get almost all their carbon from carbon dioxide, either from the atmosphere or dissolved in water.
Photosynthesis by green plants and photosynthetic plankton uses energy from the sun to split water into oxygen and hydrogen. The oxygen is released to the atmosphere, fresh water and seas, and the hydrogen joins with carbon dioxide to produce carbohydrates. Some of the carbohydrates are used, along with nitrogen, phosphorus and other elements, to form the other monomer molecules of life. Living things that do not photosynthesise have to rely on consuming other living things for their source of carbon molecules.
Their digestive systems break carbohydrates into monomers that they can use to build their own cellular structures. Respiration provides the energy needed for these reactions. In respiration oxygen rejoins carbohydrates, to form carbon dioxide and water again. The energy released in this reaction is made available for the cells. Natural abundance. Carbon is found in the sun and other stars, formed from the debris of a previous supernova.
It is built up by nuclear fusion in bigger stars. It is present in the atmospheres of many planets, usually as carbon dioxide.
On Earth, the concentration of carbon dioxide in the atmosphere is currently ppm and rising. Graphite is found naturally in many locations. Diamond is found in the form of microscopic crystals in some meteorites. In combination, carbon is found in all living things. It is also found in fossilised remains in the form of hydrocarbons natural gas, crude oil, oil shales, coal etc and carbonates chalk, limestone, dolomite etc.
Help text not available for this section currently. Elements and Periodic Table History. Carbon occurs naturally as anthracite a type of coal , graphite, and diamond. More readily available historically was soot or charcoal. Ultimately these various materials were recognised as forms of the same element.
Not surprisingly, diamond posed the greatest difficulty of identification. Naturalist Giuseppe Averani and medic Cipriano Targioni of Florence were the first to discover that diamonds could be destroyed by heating. In they focussed sunlight on to a diamond using a large magnifying glass and the gem eventually disappeared. Pierre-Joseph Macquer and Godefroy de Villetaneuse repeated the experiment in Then, in , the English chemist Smithson Tennant finally proved that diamond was just a form of carbon by showing that as it burned it formed only CO 2.
Atomic data. Bond enthalpies. Glossary Common oxidation states The oxidation state of an atom is a measure of the degree of oxidation of an atom. Oxidation states and isotopes. Glossary Data for this section been provided by the British Geological Survey. Relative supply risk An integrated supply risk index from 1 very low risk to 10 very high risk. Recycling rate The percentage of a commodity which is recycled. Substitutability The availability of suitable substitutes for a given commodity.
Reserve distribution The percentage of the world reserves located in the country with the largest reserves. Political stability of top producer A percentile rank for the political stability of the top producing country, derived from World Bank governance indicators. Political stability of top reserve holder A percentile rank for the political stability of the country with the largest reserves, derived from World Bank governance indicators.
Supply risk. Coal Diamond Graphite Coal. Relative supply risk 4. Relative supply risk 6. Relative supply risk 8. Young's modulus A measure of the stiffness of a substance.
A chemical reaction is needed to form a compound. Another chemical reaction is needed to separate the substances in a compound. Why is carbon so basic to life? This property allows carbon to form a huge variety of very large and complex molecules. In fact, there are nearly 10 million carbon-based compounds in living things! However, the millions of organic compounds can be grouped into just four major types: carbohydrates , lipids , proteins , and nucleic acids.
You can compare the four types in Table below. Each type is also described below. Carbohydrates , proteins, and nucleic acids are large molecules macromolecules built from smaller molecules monomers through dehydration reactions. In a dehydration reaction, water is removed as two monomers are joined together.
Is it possible to extract energy from leftovers? Can organic waste become useful? It may look like waste, but to some people it's green power. Find out how California dairy farms and white tablecloth restaurants are taking their leftover waste and transforming it into clean energy. The Significance of Carbon A compound found mainly in living things is known as an organic compound.
Compounds A compound is a substance that consists of two or more elements. Carbon Why is carbon so basic to life? Type of Compound Examples Elements Functions Monomer Carbohydrates sugars, starches carbon, hydrogen, oxygen provides energy to cells, stores energy, forms body structures monosaccharide Lipids fats, oils carbon, hydrogen, oxygen stores energy, forms cell membranes, carries messages Proteins enzymes, antibodies carbon, hydrogen, oxygen, nitrogen, sulfur helps cells keep their shape, makes up muscles, speeds up chemical reactions, carries messages and materials amino acid Nucleic Acids DNA, RNA carbon, hydrogen, oxygen, nitrogen, phosphorus contains instructions for proteins , passes instructions from parents to offspring, helps make proteins nucleotide Carbohydrates , proteins, and nucleic acids are large molecules macromolecules built from smaller molecules monomers through dehydration reactions.
Thus, propane, propene, and propyne follow the same pattern with three carbon molecules, butane, butene, and butyne for four carbon molecules, and so on. Double and triple bonds change the geometry of the molecule: single bonds allow rotation along the axis of the bond, whereas double bonds lead to a planar configuration and triple bonds to a linear one. These geometries have a significant impact on the shape a particular molecule can assume.
Hydrocarbon Chains : When carbon forms single bonds with other atoms, the shape is tetrahedral. When two carbon atoms form a double bond, the shape is planar, or flat. Single bonds, like those found in ethane, are able to rotate. Double bonds, like those found in ethene cannot rotate, so the atoms on either side are locked in place. The hydrocarbons discussed so far have been aliphatic hydrocarbons, which consist of linear chains of carbon atoms. Another type of hydrocarbon, aromatic hydrocarbons, consists of closed rings of carbon atoms.
Ring structures are found in hydrocarbons, sometimes with the presence of double bonds, which can be seen by comparing the structure of cyclohexane to benzene.
The benzene ring is present in many biological molecules including some amino acids and most steroids, which includes cholesterol and the hormones estrogen and testosterone. The benzene ring is also found in the herbicide 2,4-D. Benzene is a natural component of crude oil and has been classified as a carcinogen.
Some hydrocarbons have both aliphatic and aromatic portions; beta-carotene is an example of such a hydrocarbon. Hydrocarbon Rings : Carbon can form five-and six membered rings. Single or double bonds may connect the carbons in the ring, and nitrogen may be substituted for carbon. Isomers are molecules with the same chemical formula but have different structures, which creates different properties in the molecules.
The three-dimensional placement of atoms and chemical bonds within organic molecules is central to understanding their chemistry. Structural isomers such as butane and isobutane differ in the placement of their covalent bonds.
Both molecules have four carbons and ten hydrogens C 4 H 10 , but the different arrangement of the atoms within the molecules leads to differences in their chemical properties. For example, due to their different chemical properties, butane is suited for use as a fuel for cigarette lighters and torches, whereas isobutane is suited for use as a refrigerant and a propellant in spray cans. Geometric isomers, on the other hand, have similar placements of their covalent bonds but differ in how these bonds are made to the surrounding atoms, especially in carbon-to-carbon double bonds.
In the simple molecule butene C 4 H 8 , the two methyl groups CH 3 can be on either side of the double covalent bond central to the molecule. When the carbons are bound on the same side of the double bond, this is the cis configuration; if they are on opposite sides of the double bond, it is a trans configuration.
In the trans configuration, the carbons form a more or less linear structure, whereas the carbons in the cis configuration make a bend change in direction of the carbon backbone.
Isomers : Molecules that have the same number and type of atoms arranged differently are called isomers. Cis and Trans Fatty Acids : These space-filling models show a cis oleic acid and a trans eliadic acid fatty acid. Notice the bend in the molecule cause by the cis configuration. In triglycerides fats and oils , long carbon chains known as fatty acids may contain double bonds, which can be in either the cis or trans configuration. Fats with at least one double bond between carbon atoms are unsaturated fats.
When some of these bonds are in the cis configuration, the resulting bend in the carbon backbone of the chain means that triglyceride molecules cannot pack tightly, so they remain liquid oil at room temperature. On the other hand, triglycerides with trans double bonds popularly called trans fats , have relatively linear fatty acids that are able to pack tightly together at room temperature and form solid fats.
In the human diet, trans fats are linked to an increased risk of cardiovascular disease, so many food manufacturers have reduced or eliminated their use in recent years. In contrast to unsaturated fats, triglycerides without double bonds between carbon atoms are called saturated fats, meaning that they contain all the hydrogen atoms available.
Saturated fats are a solid at room temperature and usually of animal origin. Enantiomers share the same chemical structure and bonds but differ in the placement of atoms such that they are mirror images of each other. Stereoisomers are a type of isomer where the order of the atoms in the two molecules is the same but their arrangement in space is different.
Optical isomers are stereoisomers formed when asymmetric centers are present; for example, a carbon with four different groups bonded to it. Enantiomers are two optical isomers i. Every stereocenter in one isomer has the opposite configuration in the other. Compounds that are enantiomers of each other have the same physical properties except for the direction in which they rotate polarized light and how they interact with different optical isomers of other compounds.
The amino acid alanine is example of an entantiomer. The two structures, D-alanine and L-alanine, are non-superimposable. In nature, only the L-forms of amino acids are used to make proteins. Some D forms of amino acids are seen in the cell walls of bacteria, but never in their proteins.
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