Carbon is one of the most important elements kn the universe. It forms the backbone of all long, complex molecules, and is estimated to make up about 18% of our bodies.
Like many elements, carbon atoms were created within the core of a star and once it exploded at the end of its life, they were expelled into space before finding their way down to Earth.
Carbon’s importance comes from its chemical attributes. It is the most common element whose atoms have four electrons in their outer shell.
This means that carbon can form up to four bonds with other atoms. It’ll often use two of them to form bonds with other carbon atoms, creating long chains while having two bonds left over to interact with other atoms.
This opens the door for an extraordinary range of possible molecules, and makes it by far the most important element for all known forms of life. It also has an entire branch of chemistry to itself called ‘organic chemistry’.
Here are some examples of simple carbon chains.
It doesn’t take too much imagination to picture enormously complicated molecules strung together with carbon like in the image below.
Chains with different shapes create substances with totally different attributes. Carbon forms graphite, diamonds, carbon nanotubes, and many other substances just by arranging its own atoms differently.
These are called different ‘allotropes’ of carbon, meaning they are both made from the same material but the atoms have arranged themselves in different ways.
We’ve discovered over 10 million types of carbon molecules (more than any other element) but it’s estimated that this is just a fraction of the total possible number.
This huge range of molecules is the basis of life as we know it, and it is why life is said to be ‘carbon-based’.
For example, carbon chains are the backbone of essential molecules like carbohydrates, fats, sugars, proteins, alcohols, as well as DNA and RNA.
For such an important element, it’s fortunate that it is so abundant. The ‘carbon cycle’ is what we call the movement of carbon across the Earth, often moving from one molecule to the next and through countless living creatures over millions of years.
When a sapling plant grows, it needs carbon to make sugars, DNA, and other molecules for its new branches and leaves. So it will absorb carbon dioxide out of the air through its leaves, reconfigure it into the molecules it needs, and keeps growing. Most of the mass of a plant comes out of the air in this way.
When an animal eats a plant it absorbs its sugars and other molecules, breaks some of them down, and exhales carbon dioxide. When you exercise and lose a few kilograms of fat, most of it is exhaled as carbon dioxide.
Carbon travels extensively across the Earth, through the atmosphere and oceans just as easily as through plants and animals. It is one of the crucial ingredients that makes Earth an oasis for life.