This exothermic reaction is used in the iron and steel industry to smelt iron and to control the carbon content of steel: Carbon combines with some metals at high temperatures to form metallic carbides, such as the iron carbide cementite in steel and tungsten carbide, widely used as an abrasive and for making hard tips for cutting tools.The system of carbon allotropes spans a range of extremes: Atomic carbon is a very short-lived species and, therefore, carbon is stabilized in various multi-atomic structures with different molecular configurations called allotropes.The three relatively well-known allotropes of carbon are amorphous carbon, graphite, and diamond.Once considered exotic, fullerenes are nowadays commonly synthesized and used in research; they include buckyballs, The amorphous form is an assortment of carbon atoms in a non-crystalline, irregular, glassy state, not held in a crystalline macrostructure.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.Carbon is the sixth element, with a ground-state electron configuration of 1s, of which the four outer electrons are valence electrons.Its first four ionisation energies, 1086.5, 2352.6, 4620..7 k J/mol, are much higher than those of the heavier group-14 elements.
At normal pressures, carbon takes the form of graphite, in which each atom is bonded trigonally to three others in a plane composed of fused hexagonal rings, just like those in aromatic hydrocarbons.
Graphite is much more reactive than diamond at standard conditions, despite being more thermodynamically stable, as its delocalised pi system is much more vulnerable to attack.
For example, graphite can be oxidised by hot concentrated nitric acid at standard conditions to mellitic acid, C Carbon sublimes in a carbon arc, which has a temperature of about 5,800 K (5,530 °C; 9,980 °F).
Although it forms an extraordinary variety of compounds, most forms of carbon are comparatively unreactive under normal conditions.
At standard temperature and pressure, it resists all but the strongest oxidizers.
"coal") is a chemical element with symbol C and atomic number 6.