One-dimensional objects morph into new dimensions

A line is the shortest distance between two points, but "A-line," a 4-D printing system developed at Carnegie Mellon University, takes a more circuitous route. One-dimensional, "line"-shaped plastic structures produced with ...

Energy & Green Tech

Emissions-free transport speeding up in Europe

Hydrogen-powered cars are seen as a potential solution to the pollution caused by gasoline and diesel engines, but the mass roll-out of fuel cell electric vehicles (FCEVs) hasn't yet materialized. As noted in a report by ...


Researchers invent low-cost alternative to Bitcoin

The cryptocurrency Bitcoin is limited by its astronomical electricity consumption and outsized carbon footprint. A nearly zero-energy alternative sounds too good to be true, but as School of Computer and Communication Sciences ...


Quantum sensing on a chip

MIT researchers have, for the first time, fabricated a diamond-based quantum sensor on a silicon chip. The advance could pave the way toward low-cost, scalable hardware for quantum computing, sensing, and communication.

Energy & Green Tech

Future maps: We have the blueprint for livable, low-carbon cities

Over the past seven years more than 100 research projects at the Co-operative Research center for Low Carbon Living, in collaboration with industry across Australia, have pondered a very big question: How do we build future ...

Energy & Green Tech

Carbon-neutral fuels from air and green power

Several challenges associated with the energy transition can be managed by coupling the sectors of electric power and mobility. Green power could be stored in the long term, fuels of high energy density could be used in a ...

Energy & Green Tech

Making local energy markets smarter

One of Europe's main challenges is creating a low-carbon energy system that's efficient and secure. Our electricity networks in particular need to be upgraded to a system of highly efficient, flexible networks that match ...


Clearing up the 'dark side' of artificial leaves

While artificial leaves hold promise as a way to take carbon dioxide—a potent greenhouse gas—out of the atmosphere, there is a "dark side to artificial leaves that has gone overlooked for more than a decade," according ...

page 1 from 11


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