Carbon is the sixth element listed on the Periodic Table of the Elements. Represented by the symbol C, carbon is the single most important element to the existence of life as we know it. Carbon is present in every living thing on Earth and is the second most abundant element found in humans. Carbon possesses a number of special chemical and physical properties that make it unusually suitable for the formation of complex compounds necessary for life.
A stable carbon atom possesses six protons, six neutrons and six electrons, resulting in an atomic mass of 12.011 and the sixth position on the Periodic Table of the Elements. Four of the electrons are found in the outer shell of the atom while the other two are located in the inner shell. Solid-state molecules consisting of only bonded carbon atoms are arranged in a tetrahedral or hexagonal shape, depending on the physical form of the substance.
Carbon burns in oxygen to create carbon dioxide and carbon monoxide. Carbon can also form carbides when heated with oxides; for example, calcium oxide heated with carbon forms calcium carbide and carbon monoxide. In addition, carbon compounds such as carbon monoxide act as a reducing agent to metallic oxides. For example, applying extreme heat from a source such as a furnace to ferric oxide in a carbon monoxide environment reduces the ferric oxide to iron.
Carbon is allotropic, meaning it exists in multiple physical forms, despite the fact that they are chemically similar. You can find carbon as graphite, diamond or carbon residue left behind when carbon-based compounds are subjected to heat. Graphite, which exists in a sheet-like structure, is soft and conducts electricity. Graphite is also more likely to take part in chemical reactions. By contrast, diamond is extremely hard, does not conduct electricity and is inert. Carbon residue includes coal, charcoal and other substances that humans use for energy.
Carbon is capable of forming chains of carbon in single, double and triple bonds with other carbon atoms. Called catenation, this process is the basis for the creation of organic compounds and the study of organic chemistry. Although other elements such as silicon or germanium are capable of limited catenation, carbon is able to form chains of unlimited size. In addition, only carbon is able to catenate double and triple bonds whereas other elements are limited to single bonds.