Health

How dangerous is vaping? The science remains hazy

Is vaping a useful tool for quitting smoking or just a new way of harming your health? Countries around the world are beginning to consider this question and India on Wednesday announced a total ban on the sale of e-cigarettes,

Pediatrics

Researchers refine guidelines for pediatric brain injuries

When a child suffers a head trauma, medical professionals are in high gear to prevent further damage to a developing brain. Measuring and regulating the child's level of carbon dioxide is critical to ensuring the brain is ...

Medical research

Scars: Gone with the foam

A scar on the elbow that is strained with every movement, or a foot, on which a wound simply does not want to close—poorly healing injuries are a common cause of health restrictions. And although millions of people are ...

Cardiology

Damaged hearts rewired with nanotube fibers

Thin, flexible fibers made of carbon nanotubes have now proven able to bridge damaged heart tissues and deliver the electrical signals needed to keep those hearts beating.

Health

How climate change could make your allergies worse

Sprouting daffodils, magnolias, and cherry blossoms serve as cues to put away puffy coats and say goodbye to winter. But for more than 50 million Americans (myself included), the beautiful flowers also signal something else: ...

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Carbon

Carbon (pronounced /ˈkɑrbən/) is the chemical element with 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. There are three naturally occurring isotopes, with 12C and 13C being stable, while 14C is radioactive, decaying with a half-life of about 5730 years. Carbon is one of the few elements known since antiquity. The name "carbon" comes from Latin language carbo, coal, and, in some Romance and Slavic languages, the word carbon can refer both to the element and to coal.

There are several allotropes of carbon of which the best known are graphite, diamond, and amorphous carbon. The physical properties of carbon vary widely with the allotropic form. For example, diamond is highly transparent, while graphite is opaque and black. Diamond is among the hardest materials known, while graphite is soft enough to form a streak on paper (hence its name, from the Greek word "to write"). Diamond has a very low electrical conductivity, while graphite is a very good conductor. Under normal conditions, diamond has the highest thermal conductivity of all known materials. All the allotropic forms are solids under normal conditions but graphite is the most thermodynamically stable.

All forms of carbon are highly stable, requiring high temperature to react even with oxygen. The most common oxidation state of carbon in inorganic compounds is +4, while +2 is found in carbon monoxide and other transition metal carbonyl complexes. The largest sources of inorganic carbon are limestones, dolomites and carbon dioxide, but significant quantities occur in organic deposits of coal, peat, oil and methane clathrates. Carbon forms more compounds 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.

Carbon is one of the least abundant elements in the Earth's crust, but the fourth most abundant element in the universe by mass after hydrogen, helium, and oxygen. It is present in all known lifeforms, and in the human body carbon is the second most abundant element by mass (about 18.5%) after oxygen. This abundance, together with the unique diversity of organic compounds and their unusual polymer-forming ability at the temperatures commonly encountered on Earth, make this element the chemical basis of all known life.

This text uses material from Wikipedia, licensed under CC BY-SA