- Carbon (C) is a nonmetal with atomic number 6, located in Group 14 of the periodic table.
- It is unique among elements for its unparalleled ability to form a vast variety of compounds, more than any other element, due to its tetravalent nature—possessing four valence electrons that allow it to form strong covalent bonds with itself and many other elements.
- Its atomic structure consists of six protons, typically six neutrons (in the most common isotope), and six electrons arranged in two shells (two in the inner shell and four in the outer shell).
- Carbon exists naturally as three isotopes: carbon-12 (¹²C), which accounts for about 98.9% of all carbon; carbon-13 (¹³C), a stable isotope making up about 1.1%; and carbon-14 (¹⁴C), a radioactive isotope used in radiocarbon dating with a half-life of about 5,730 years.
- Carbon is the fourth most abundant element in the universe by mass, after hydrogen, helium, and oxygen. It is formed in stars through the triple-alpha process, in which three helium-4 nuclei (⁴He) fuse to create a carbon-12 nucleus. On Earth, carbon is a fundamental component of all known life forms and the backbone of organic chemistry. It is found in a wide variety of forms, from atmospheric carbon dioxide (CO₂) and dissolved carbonate in oceans, to fossil fuels, minerals, and living organisms. Carbon cycles continuously through the biosphere, atmosphere, oceans, and lithosphere in processes collectively known as the carbon cycle, which is vital for regulating Earth’s climate.
- Historically, humans have known carbon in its elemental forms since ancient times, such as charcoal, soot, and graphite. Diamonds, another crystalline form of carbon, have been prized for millennia as gemstones and cutting tools. Antoine Lavoisier in the late 18th century recognized carbon as a distinct element, contributing to the modern understanding of chemical elements. Carbon’s allotropes include diamond, graphite, graphene, carbon nanotubes, and amorphous carbon—each with vastly different properties despite being composed solely of carbon atoms. Diamond is the hardest known natural material, an excellent electrical insulator, and an outstanding thermal conductor, while graphite is soft, opaque, and a good electrical conductor.
- The versatility of carbon’s chemical bonding underpins the immense diversity of organic compounds, from simple molecules like methane (CH₄) to complex biomolecules such as proteins, nucleic acids, and lipids. This versatility is central to the chemistry of life. Industrially, carbon is essential in steelmaking (as a strengthening component in alloys), in carbon black for rubber products, in activated carbon for filtration, and in graphite electrodes for electric arc furnaces. Carbon-based nanomaterials like graphene and carbon nanotubes are at the forefront of advanced material research due to their exceptional strength, conductivity, and lightweight nature.
- Carbon also plays a pivotal role in environmental and energy concerns. Carbon dioxide and methane are major greenhouse gases influencing Earth’s climate. Human activities, particularly the burning of fossil fuels and deforestation, have significantly increased atmospheric CO₂ levels, leading to global warming and climate change. Addressing these challenges involves both reducing carbon emissions and developing carbon capture and storage (CCS) technologies, as well as transitioning to renewable energy sources.
- Although carbon is essential to life and industry, certain forms and compounds can be hazardous. Inhalation of fine carbon particles, such as soot, can damage the lungs, while carbon monoxide (CO) is a colorless, odorless, and highly toxic gas that interferes with oxygen transport in the blood. These risks underscore the importance of managing carbon-related processes safely.
