Carbon

Carbon is a chemical element with the 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. It belongs to the p-block. Three isotopes occur naturally, 12C and 13C being stable, while 14C is a radionuclide, decaying with a half-life of about 5,730 years. Carbon is one of the few elements known since antiquity.

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.

The atoms of carbon can bond together in diverse ways, resulting in various allotropes of carbon. The best known allotropes are graphite, diamond, 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, while diamond is the hardest naturally occurring material known. Graphene, a single layer of graphite, is a semimetal with unusual electronic properties.

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 enormous variety of compounds, most forms of carbon are relatively nonreactive under normal conditions. At high temperatures, carbon combines with oxygen to form carbon dioxide and with hydrogen to form carbon monoxide.

In addition to its role in the biosphere, carbon is a key ingredient in many energy sources, notably fossil fuels like coal, oil, and natural gas. It is also found in many plastics, drugs, and other synthetic materials.

Uses of Carbon

Carbon is used in various forms in numerous fields:

- Diamond: Due to its extreme hardness and high thermal conductivity, diamond is used in cutting, grinding, and drilling tools, as well as in heat sinks. - Graphite: Employed in high-temperature lubricants, batteries, and lightweight structural materials. - Activated carbon: Used in water purification, gas purification, and in medical applications to treat poisonings and overdoses. - Carbon fiber: Known for its high strength-to-weight ratio, used in the manufacturing of composite materials for aerospace, automotive, and sporting goods. - Carbon black: Used as a reinforcing filler in tires and other rubber products and as a pigment in inks, coatings, and plastics.

Environmental Impact

Carbon plays a dual role in the Earth's environment. It is crucial for life, yet its emission in the form of carbon dioxide (CO2), a greenhouse gas, from burning fossil fuels is a major driver of global warming and climate change. Efforts to reduce carbon emissions and enhance carbon sequestration are vital to mitigating climate change.

See Also

- Carbon cycle - Carbon footprint - Carbon sequestration - Greenhouse gas

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