Atomic Number: 6
Relative Atomic Mass: 12.01
Appearance: Black solid (or clear solid when in diamond form)
What do pencils, coal, diamonds, and every living thing on Earth have in common? They all contain carbon, the sixth element on the periodic table! Every living organism on the planet is a carbon-based life form and carbon is the second most abundant element in the human body (after oxygen). Humans have used carbon in its charcoal-like form since prehistoric times, and it was first used in its diamond form in China about 4500 years ago. However, more recently, a buildup of carbon dioxide in the atmosphere has also contributed to climate change.
Allotropism and nanotubes
The really cool thing about carbon is its allotropism. This means it can take on a variety of different forms—from the graphite in a pencil to the diamond in a specialized cutting tool—depending on how its atoms are arranged. Graphite arranges itself nicely into sheets, which is why it works so well for writing. By contrast, diamond has a lattice structure, which makes it one of the strongest substance ever discovered. A few other elements are also allotropic. For example, oxygen atoms can take the form of diatomic oxygen (O2) or ozone (O3).
Another carbon allotrope, fullerene, was only discovered in 1985. It is used for carbon nanotubes, which are the most important carbon-related discovery in the last thirty years. Fullerene used in carbon nanotubes has a buckyball structure that looks like a soccer ball. Nanotubes are also fluorescent, which means they emit a different wavelength of light than they initially absorb, causing them to glow a different colour.
Did you know? Graphene is the strongest substance ever discovered—even stronger than diamonds. It is made up of a one-atom-thick layer of carbon atoms in a honeycomb shape.
This means that doctors could inject carbon nanotubes into a patient to locate abnormalities, such as tumours. In fact, the use of injected nanotubes could replace the use of expensive, bulky machines like magnetic resonance imaging (MRI) scanners in hospitals, giving patients easier access to life-saving cancer diagnoses.
Carbon dioxide and climate change
In recent years, the threat of climate change has given carbon a bit of a bad name. When carbon bound to oxygen in the form of carbon dioxide (CO2) collects in the atmosphere, it creates a greenhouse effect that traps the sun’s UV rays and warms up the planet. Other greenhouse gases include methane (CH4), water vapour (H2O) and nitrous oxide (N2O). Like carbon dioxide, they trap infrared radiation so it can’t escape the atmosphere. Levels of greenhouse gases in the atmosphere have been steadily increasing since the industrial revolution began in the late 1700s.
Although global warming is a major threat, having a certain amount CO2 in the atmosphere is a good thing. Without it, life on Earth probably might not be possible at all. It’s the combination of Earth’s location in the solar system and the warming potential of CO2 in the atmosphere that creates an ideal environment for life. When there’s too much CO2 the planet gets too hot, the ice caps melt and and sea levels rise—with potentially disastrous consequences. But if there were too little CO2, the planet would cool and we might all freeze to death!
Did you know? “Perfect” diamonds are colourless, although structural or chemical impurities may cause them to have colour. Coloured diamonds can actually be used to detect magnetic fields.
Some researchers are trying to address global warming through a process called carbon capture. It involves removing huge amounts of CO2 from the atmosphere, liquefying it, and storing it underground. Similar to the way water softener pellets pull ions out of hard water, artificial trees are being designed to mimic the way that real trees pull carbon out of the atmosphere, but at a rate 1000 times faster. The carbon is held in artificial leaves, which can be washed to pull out the CO2, which is then compressed until the gas turns into a liquid.
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Whether it’s in diamonds, in you, or in the air, carbon is everywhere and life wouldn’t be possible without it. Medical research could lead to carbon nanotubes saving countless lives while making large, expensive medical equipment equipment obsolete. Nevertheless, climate change is a growing threat, as rising carbon dioxide levels in the atmosphere contribute to a greenhouse effect.
Do you think carbon capture is a good way of addressing this threat? What else can be done about the problem of carbon emissions?
News release discussing research into the potential of fullerene spheres to be used in medical imaging.
Article on reducing the amount of pollution caused by burning coal, including carbon capture and sequestration (CCS) systems.
General reflection on the importance of carbon for life on Earth.