Carbon From Wikipedia, the free encyclopedia This article is about the chemical element. For other uses, see Carbon (disambiguation). This is a good article. Click here for more information.Page semi-protected Carbon 6C - ↑ C ↓ Si boron ← carbon → nitrogen Carbon in the periodic table Appearance diamond: clear graphite: black Spectral lines of Carbon General properties Name, symbol, number carbon, C, 6 Pronunciation /ˈkɑrbən/ Element category polyatomic nonmetal sometimes considered a metalloid Group, period, block 14, 2, p Standard atomic weight 12.011(1) Electron configuration [He] 2s2 2p2 2, 4 Physical properties Phase solid Density (near r.t.) amorphous:[1] 1.8–2.1 g·cm−3 Density (near r.t.) diamond: 3.515 g·cm−3 Density (near r.t.) graphite: 2.267 g·cm−3 Sublimation point 3915 K, 3642 °C, 6588 °F Triple point 4600 K, 10800[2][3] kPa Heat of fusion 117 (graphite) kJ·mol−1 Molar heat capacity diamond: 6.155 J·mol−1·K−1 Molar heat capacity graphite: 8.517 J·mol−1·K−1 Atomic properties Oxidation states 4, 3[4], 2, 1[5], 0, −1, −2, −3, −4[6] Electronegativity 2.55 (Pauling scale) Ionization energies (more) 1st: 1086.5 kJ·mol−1 2nd: 2352.6 kJ·mol−1 3rd: 4620.5 kJ·mol−1 Covalent radius sp3: 77 pm sp2: 73 pm sp: 69 pm Van der Waals radius 170 pm Miscellanea Crystal structure diamond Carbon has a diamond crystal structure (diamond, clear) simple hexagonal Carbon has a Simple Hexagonal crystal structure (graphite, black) Magnetic ordering diamagnetic[7] Thermal conductivity diamond: 900-2300 W·m−1·K−1 Thermal conductivity graphite: 119-165 W·m−1·K−1 Thermal expansion (25 °C) (diamond) 0.8[8] µm·m−1·K−1 Speed of sound (thin rod) (20 °C) (diamond) 18350 m·s−1 Young's modulus diamond: 1050[8] GPa Shear modulus diamond: 478[8] GPa Bulk modulus diamond: 442[8] GPa Poisson ratio diamond: 0.1[8] Mohs hardness diamond: 10 graphite: 1-2 CAS registry number 7440-44-0 History Discovery Egyptians and Sumerians[9] (3750 BC) Recognized as an element by Antoine Lavoisier[10] (1789) Most stable isotopes Main article: Isotopes of carbon iso NA half-life DM DE (MeV) DP 11C syn 20 min β+ 0.96 11B 12C 98.9% 12C is stable with 6 neutrons 13C 1.1% 13C is stable with 7 neutrons 14C trace 5730 y β− 0.15 0 14N v t e · references Carbon (from Latin: carbo "coal") is the chemical element with symbol C and atomic number 6. As a member of group 14 on the periodic table, it is nonmetallic and tetravalent—making four electrons available to form covalent chemical bonds. There are three naturally occurring isotopes, with 12C and 13C being stable, while 14C is radioactive, decaying with a half-life of about 5,730 years.[11] Carbon is one of the few elements known since antiquity.[12] There are several allotropes of carbon of which the best known are graphite, diamond, and amorphous carbon.[13] The physical properties of carbon vary widely with the allotropic form. For example, diamond is highly transparent, while graphite is opaque and black. Diamond is the hardest naturally-occurring material known, while graphite is soft enough to form a streak on paper (hence its name, from the Greek word "γράφω" which means "to write"). Diamond has a very low electrical conductivity, while graphite is a very good conductor. Under normal conditions, diamond, carbon nanotube and graphene have the highest thermal conductivities of all known materials. All carbon allotropes are solids under normal conditions, with graphite being the most thermodynamically stable form. They are chemically resistant and require high temperature to react even with oxygen. The most common oxidation state of carbon in inorganic compounds is +4, while +2 is found in carbon monoxide and other transition metal carbonyl complexes. The largest sources of inorganic carbon are limestones, dolomites and carbon dioxide, but significant quantities occur in organic deposits of coal, peat, oil and methane clathrates. Carbon forms a vast number of compounds, more than any other element, with almost ten million compounds described to date,[14] which in turn are a tiny fraction of such compounds that are theoretically possible under standard conditions. Carbon is the 15th most abundant element in the Earth's crust, and the fourth most abundant element in the universe by mass after hydrogen, helium, and oxygen. It is present in all known life forms, and in the human body carbon is the second most abundant element by mass (about 18.5%) after oxygen.[15] This abundance, together with the unique diversity of organic compounds and their unusual polymer-forming ability at the temperatures commonly encountered on Earth, make this element the chemical basis of all known life. On 21 February 2014, NASA announced a greatly upgraded database for tracking polycyclic aromatic hydrocarbons (PAHs) in the universe. According to scientists, more than 20% of the carbon in the universe may be associated with PAHs, possible starting materials for the formation of life. PAHs seem to have been formed shortly after the Big Bang, are widespread throughout the universe, and are associated with new stars and exoplanets.[16] Contents [hide] 1 Characteristics 1.1 Allotropes 1.2 Occurrence 1.3 Isotopes 1.4 Formation in stars 1.5 Carbon cycle 2 Compounds 2.1 Organic compounds 2.2 Inorganic compounds 2.3 Organometallic compounds 3 History and etymology 4 Production 4.1 Graphite 4.2 Diamond 5 Applications 5.1 Diamonds 6 Precautions 7 Bonding to carbon 8 See also 9 References 10 External links Characteristics Theoretically predicted phase diagram of carbon The different forms or allotropes of carbon (see below) include the hardest naturally occurring substance, diamond, and also one of the softest known substances, graphite. Moreover, it has an affinity for bonding with other small atoms, including other carbon atoms, and is capable of forming multiple stable covalent bonds with such atoms. As a result, carbon is known to form almost ten million different compounds; the large majority of all chemical compounds.[14] Carbon also has the highest sublimation point of all elements. At atmospheric pressure it has no melting point as its triple point is at 10.8 ± 0.2 MPa and 4,600 ± 300 K (~4,330 °C or 7,820 °F),[2][3] so it sublimes at about 3,900 K.[17][18] Carbon sublimes in a carbon arc which has a temperature of about 5,800 K (5,530 °C; 9,980 °F). Thus, irrespective of its allotropic form, carbon remains solid at higher temperatures than the highest melting point metals such as tungsten or rhenium. Although thermodynamically prone to oxidation, carbon resists oxidation more effectively than elements such as iron and copper that are weaker reducing agents at room temperature. Carbon compounds form the basis of all known life on Earth, and the carbon-nitrogen cycle provides some of the energy produced by the Sun and other stars. Although it forms an extraordinary variety of compounds, most forms of carbon are c