Carbon
Introduction
Carbon is a chemical element with the symbol C and atomic number 6. It is nonmetallic and tetravalent—making four electrons available to form covalent chemical bonds. It belongs to group 14 of the periodic table.
Properties and Characteristics
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.
Allotropes
Carbon has several allotropes, or different forms in which it can exist. These include graphite, one of the softest substances, and diamond, the hardest naturally occurring substance. It also includes the fullerene, carbon nanotubes, and graphene.
Occurrence
Carbon is the main element of organic chemistry, and it forms a vast number of compounds, more than any other element, with almost ten million pure organic compounds described to date, which in turn are a tiny fraction of such compounds that are theoretically possible under standard conditions.
Uses
Carbon is used in various forms in the manufacture of many synthetic organic chemicals and is employed in the form of activated charcoal for purifying gases and as a black pigment in printing ink, artist's oil paint and water colours, the rubber tire industry, and (in the form of lampblack) mascara. It is also used in automotive products and food colouring.
Biological Role
Carbon is a key component of all known life on Earth, representing approximately 45-50% of all dry biomass. Complex molecules are made up of carbon bonded with other elements, especially oxygen and hydrogen and frequently also with nitrogen, phosphorus and sulfur.
Environmental Impact
Carbon, in the form of carbon dioxide, is a greenhouse gas. When released into the atmosphere, it traps heat and contributes to global warming. The process of carbon sequestration seeks to remedy this by capturing and storing carbon dioxide.