Carbon C (Element)

Carbon belongs to the 14th group of the periodic table. The entire earth’s core is made up of only about 0.025 percent of carbon. Hence we can also say at the earth’s core we can find the purest form of carbon. A radionuclide is a compound where among the three isotopes 12C and 13C are the stable ones, while 14C is a radionuclide. One of the few elements known since antiquity is carbon. The two known allotropes of carbon are graphite and diamond. 

The appearance of graphite is black, and metallic-looking whereas diamond is looking. In the periodic table, the Atomic number of carbon is 6, it is placed in period 2 and the p-block of the blocks column in the periodic table. The 15th most abundant element present in the Earth’s crust is Carbon C, and also is the 4th most abundant element on earth by mass after hydrogen, helium, and oxygen. 

Carbon usually serves as a common element of all known life because of its uncommon diversity of all organic compounds, and its ability to form polymers at different temperatures commonly encountered on the surface of the Earth. After oxygen, by mass carbon is the second most abundant element in the human body. The atoms of carbon can bond together in manifold ways, resulting in the formation of various allotropes of carbon such as graphite, diamond, amorphous carbon, and fullerenes. 

Allotropes

In the periodic table, the purest form of carbon or atomic carbon is a species with a very short lifespan. Thus, the carbon is needed to be equilibrated in numerous multi-atomic structures with diverse molecular configurations known as allotropes. The three well-known allotropes of carbon formed are amorphous carbon, graphite, and diamond. Fullerenes were once considered exotic, but nowadays they are commonly synthesised and used in research. 

The fullerenes mainly include buckyballs, carbon nanotubes, carbon nanotubes, and nanofibers. Various other exotic allotropes have also been discovered, for example, lonsdaleite, glassy carbon, carbon nanofoam, and also linear acetylenic carbon known as carbyne.

A two-dimensional sheet of carbon with atoms arranged in a hexagonal lattice is what we call graphene. In conclusion from the research of 2009, graphene is discovered to be the strongest material ever tested. Graphene requires some further technological development to carry out the process of separating it from graphite before it is economical for industrial processes. 

If the process seems successful, graphene could even be used in the construction of a space elevator. Even to safely store hydrogen for use in a hydrogen-based engine in cars it could also be used to satisfy these processes. 

The amorphous form of carbon is mainly seen as an assortment of carbon atoms in a non-crystalline, irregular, glassy state, not formed in a macrostructure of crystals. The amorphous form is mainly seen in a powder form with the main constituent of substances such as charcoal, lampblack (soot), and activated carbon. Carbon takes the form of graphite, at normal pressure whereas, at very high pressures, a more compacted allotrope is formed from the purest form of carbon is diamond. 

Another synthetic crystalline formed from carbon with a formation of a graphite-like structure is fullerenes. Fullerenes are made of mainly flat hexagonal cells only. However, in some cases, the formation of fullerenes may be pentagons, nonplanar hexagons, or even heptagons of carbon atoms.

Occurrence

Carbon is a pretty abundant component present in the Sun, stars, comets, and some other atmospheres of most planets. Microscopic diamonds are present in some meteorites that were formed when the Solar System was still a protoplanetary disk. Microscopic diamonds can also be formed by the immense pressure and extremely high temperature at the sites of meteorite impacts. 

More than 20% of the carbon present in the universe is PAH-associated (complex compounds of carbon and hydrogen without oxygen).  PAHs recently seem to have been formed “a couple of billion years” after the Big Bang, and the theories are widespread throughout the universe.

There is an estimation made by scientists that the solid earth contains approximately 730 ppm of carbon, with 2000 ppm in the core and 120 ppm in the combined mantle and crust as a whole. Thus, the mass of the earth will be 5.972×1024 kg, which results in 4360 million gigatonnes of carbon. This concludes that there is much more on the surface than the amount of carbon in the oceans or atmosphere (below). 

Do you know what carbon sequestration is? the long-term storage of carbon in various mediums such as plants, soils, geologic formations, and also the ocean. 

Carbon sequestration can occur both naturally or as a result of anthropogenic activity (such as the burning of fossil fuels has helped in releasing carbon from its long-term geologic storage in the form of coal, petroleum, other natural gases and has delivered it to the atmosphere as carbon dioxide gas) that mainly refers to the storage of carbon that consists of immediate potential to change into carbon dioxide gas.

Isotopes

Isotopes of carbon are known as atomic nuclei that contain six protons plus several neutrons (varying from 2 to 16). Carbon consists of mainly two stable, naturally occurring isotopes. On earth, the isotope carbon-12 (12C) forms 98.93% of the carbon,  while carbon-13 (13C) forms only the remaining 1.07% of the carbon. 

However, in carbon compounds, the concentration of 12C is further seen to be increased in biological materials because biochemical reactions discriminate against 13C. One of the naturally occurring radioisotopes mainly created in the upper atmosphere (lower stratosphere and upper troposphere) is Carbon-14 (14C) which is formed by the interaction of nitrogen with cosmic rays. 

There are mainly 15 isotopes of carbon that we know of and one of the shortest-lived of these is 8C which decays due to photon emission and alpha decay and has a half-life of 1.98739 × 10−21 s. The exotic 19 C is known for exhibiting a nuclear halo, which means its radius is appreciably larger than would be expected if the nucleus were a sphere of constant density.

Conclusion

Currently, the most commercially viable diamond deposits are in Russia, Botswana, Australia, and the Democratic Republic of Congo. In 2005, Russia’s diamond production, also from the purest form of carbon, was almost one-fifth of the global diamond output, as reported by the British Geological Survey. 

Australia owns the richest diamondiferous pipe with an average production reaching peak levels of 42 metric tons which means 41 long tons; 46 short tons per year in the 1990s.