The Element Carbon

The element Carbon is one of the most important for life. This is because of the way it can bond to other elements to form an infinite variety of molecules, as explained below.

Isotopes of Carbon

All carbon atoms contain 6 protons in their nuclei and therefore attract six electrons in their neutral unbound state. As with all the other elements, the isotopes are versions of the carbon atom that have different numbers of neutrons in the nucleus.

The most common form of Carbon is 12-Carbon. The "12" refers to the total number of nuclear particles, both protons and neutrons. Since we know that Carbon has 6 protons, this most common isotope therefore also has 6 protons in the nucleus. This version of Carbon accounts for almost 99% of the carbon atoms in any sample.

Many Carbon isotopes have been identified. The total range of number of neutrons is from 2 to 16, giving a total if 15 isotopes. Of all these isotopes, only 12-Carbon, 13-Carbon and 14-Carbon occur naturally. Of these, 14-Carbon is unstable and the nucleus is prone to decay. This isotope has a half-life of approximately 5700 years and is regularly used for dating fossil remains and soil and ice core samples.


The Electron Structure of Carbon

Carbon has a total of 6 electrons. If we put these into the electron subshell filling pattern we end up with an electron configuration of 1s2 2s2 2p2. This means that the element Carbon has four outer shell electrons which we can use to make an electron dot diagram that looks like the one to the left.

Elements are most stable when they have 8 electrons in their outer electron shell. However, elements are unable to gain or lose more than three electrons to achieve this, so Carbon can do neither of these things. It overcomes its need for an extra four electrons by SHARING electrons with other atoms.

We can gain a more detailed understanding of the electron structure of the element Carbon by looking at the layered view of the subshells, as shown below. The outer electron shell, which consists of the 2s and 2p subshells combined, is considered as a whole for the purposes of filling and therefore bonding.

This sharing process requires separate treatment as its variations and implications are very wide ranging. The bonding of carbon has resulted in all our fossil fuels, be they coal or oil and gas.

Carbon also has a range of allotropes, or pure forms. Some of these are naturally occurring such as graphite and diamond, whereas others can be manufactured. Examples of this last category are carbon nanotubes, buckeyballs and so on. The potential for use of Carbon allotropes in solar cells has only begun to be investigated. Several experimental varieties of quantum dot solar cells have been constructed that have been able to generate electrical current with incredibly small amounts of physical materials. These cells, along with other varieties of quantum dot circuits, are in the very early stages of development and are not yet close to commercial viability.