Carbon

Carbon, ₆C

Graphite (left) and diamond (right), two allotropes of carbon
Carbon
Allotropes	graphite, diamond and more (see Allotropes of carbon)
Appearance	graphite: black, metallic-looking diamond: clear
Standard atomic weight Ar°(C)
	[12.0096, 12.0116][1] 12.011±0.002 (abridged)[2]
Carbon in the periodic table
Hydrogen Helium Lithium Beryllium Boron Carbon Nitrogen Oxygen Fluorine Neon Sodium Magnesium Aluminium Silicon Phosphorus Sulfur Chlorine Argon Potassium Calcium Scandium Titanium Vanadium Chromium Manganese Iron Cobalt Nickel Copper Zinc Gallium Germanium Arsenic Selenium Bromine Krypton Rubidium Strontium Yttrium Zirconium Niobium Molybdenum Technetium Ruthenium Rhodium Palladium Silver Cadmium Indium Tin Antimony Tellurium Iodine Xenon Caesium Barium Lanthanum Cerium Praseodymium Neodymium Promethium Samarium Europium Gadolinium Terbium Dysprosium Holmium Erbium Thulium Ytterbium Lutetium Hafnium Tantalum Tungsten Rhenium Osmium Iridium Platinum Gold Mercury (element) Thallium Lead Bismuth Polonium Astatine Radon Francium Radium Actinium Thorium Protactinium Uranium Neptunium Plutonium Americium Curium Berkelium Californium Einsteinium Fermium Mendelevium Nobelium Lawrencium Rutherfordium Dubnium Seaborgium Bohrium Hassium Meitnerium Darmstadtium Roentgenium Copernicium Nihonium Flerovium Moscovium Livermorium Tennessine Oganesson – ↑ C ↓ Si boron ← carbon → nitrogen
Atomic number (Z)	6
Group	group 14 (carbon group)
Period	period 2
Block	p-block
Electron configuration	[He] 2s2 2p2
Electrons per shell	2, 4
Physical properties
Phase at STP	solid
Sublimation point	3915 K ​(3642 °C, ​6588 °F)
Density (near r.t.)	graphite: 2.266 g/cm3[3][4] diamond: 3.515 g/cm3 amorphous: 1.8–2.1 g/cm3
Triple point	4600 K, ​10,800 kPa[5][6]
Heat of fusion	graphite: 117 kJ/mol
Molar heat capacity	graphite: 8.517 J/(mol·K) diamond: 6.155 J/(mol·K)
Atomic properties
Oxidation states	−4, −3, −2, −1, 0, +1,[7] +2, +3,[8] +4[9] (a mildly acidic oxide)
Electronegativity	Pauling scale: 2.55
Ionization energies	1st: 1086.5 kJ/mol 2nd: 2352.6 kJ/mol 3rd: 4620.5 kJ/mol (more)
Covalent radius	sp3: 77 pm sp2: 73 pm sp: 69 pm
Van der Waals radius	170 pm
Spectral lines of carbon
Other properties
Natural occurrence	primordial
Crystal structure	graphite: ​simple hexagonal (hP4)
Lattice constants	a = 246.14 pm c = 670.94 pm (at 20 °C)[3]
Crystal structure	diamond: ​face-centered diamond-cubic (cF8)
Lattice constant	a = 356.707 pm (at 20 °C)[3]
Thermal expansion	diamond: 0.8 µm/(m⋅K) (at 25 °C)[10]
Thermal conductivity	graphite: 119–165 W/(m⋅K) diamond: 900–2300 W/(m⋅K)
Electrical resistivity	graphite: 7.837 µΩ⋅m[11]
Magnetic ordering	diamagnetic[12]
Molar magnetic susceptibility	diamond: −5.9×10−6 cm3/mol[13]
Young's modulus	diamond: 1050 GPa[10]
Shear modulus	diamond: 478 GPa[10]
Bulk modulus	diamond: 442 GPa[10]
Speed of sound thin rod	diamond: 18,350 m/s (at 20 °C)
Poisson ratio	diamond: 0.1[10]
Mohs hardness	graphite: 1–2 diamond: 10
CAS Number	atomic carbon: 7440-44-0 graphite: 7782-42-5 diamond: 7782-40-3
History
Discovery	Egyptians and Sumerians[14] (3750 BCE)
Recognized as an element by	Antoine Lavoisier[15] (1789)
Isotopes of carbon v e
Main isotopes Decay abun­dance half-life (t1/2) mode pro­duct 11C synth 20.34 min β+ 11B 12C 98.9% stable 13C 1.06% stable 14C 1 ppt (1⁄1012) Preview warning: Infobox C isotopes: Abundance percentage not recognised "na=1 ppt (1⁄1012)" cat#% 5.70×103 y β− 14N
Category: Carbon view talk edit | references

Carbon (from Latin carbo 'coal') is a chemical element; it has symbol C and atomic number 6. It is nonmetallic and tetravalent—meaning that its atoms are able to form up to four covalent bonds due to its valence shell exhibiting 4 electrons. It belongs to group 14 of the periodic table.^[16] Carbon makes up about 0.025 percent of Earth's crust.^[17] Three isotopes occur naturally, ¹²C and ¹³C being stable, while ¹⁴C is a radionuclide, decaying with a half-life of about 5,730 years.^[18] Carbon is one of the few elements known since antiquity.^[19]

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. Carbon's abundance, its unique diversity of organic compounds, and its unusual ability to form polymers at the temperatures commonly encountered on Earth, enables this element to serve as a common element of all known life. It is the second most abundant element in the human body by mass (about 18.5%) after oxygen.^[20]

The atoms of carbon can bond together in diverse ways, resulting in various allotropes of carbon. Well-known allotropes include graphite, diamond, amorphous carbon, and fullerenes. The physical properties of carbon vary widely with the allotropic form. For example, graphite is opaque and black, while diamond is highly transparent. Graphite is soft enough to form a streak on paper (hence its name, from the Greek verb "γράφειν" which means "to write"), while diamond is the hardest naturally occurring material known. Graphite is a good electrical conductor while diamond has a low electrical conductivity. Under normal conditions, diamond, carbon nanotubes, 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 at standard temperature and pressure. 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 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, with about two hundred million having been described and indexed;^[21] and yet that number is but a fraction of the number of theoretically possible compounds under standard conditions.