The carbon-12 it is the most abundant isotope of the element carbon, with 98.93% abundance. In addition, it is the main responsible for all the properties and applications attributed to the element carbon..
The 12C, with an atomic mass of exactly 12 daltons, serves as a reference for establishing the atomic masses of the rest of the nuclides. The atom of 12C consists of six protons, neutrons, and electrons; however, the mass of the electrons is considered negligible.
Elements usually have atomic masses expressed as whole numbers, followed by decimals, because elements can have several stable isotopes.
Therefore, the atomic masses of the elements are expressed as the weighted average of the atomic masses of their different isotopes. Considering that the 12C has an abundance of 98.93%, and the 13C an abundance of 1.15%, the atomic mass of carbon is 12.011 daltons.
The atomic mass of an element is expressed as the average of the atomic masses of its different atoms in relation to one twelfth of the mass of the element. 12C, known as a unified atomic mass unit; previously abbreviated as "uma", and currently as "u".
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In the image above, the notation or nuclear symbol for the carbon-12 isotope was shown..
Describing it is the same as establishing the characteristics of the carbon atom par excellence. Its atomic number 6 indicates the number of protons in its nucleus. The number 12 is equal to the sum of the protons and neutrons, and is therefore the atomic mass; which is proportional to the nuclear mass.
And although this notation does not show it, there are 6 electrons that counteract the positive charge of the protons in the nucleus. From the point of view of chemical bonds, four of these six electrons are the ones that establish the foundations of life as we know it..
Dalton's research (1810) indicated that water contained a percentage of oxygen of 87.7% and of hydrogen of 12.5%. But, Dalton pointed out that the formula for the water was OH. Davy and Berzelius (1812) corrected the formula for water to HtwoOR.
Subsequently, Berzelius found the following water composition: oxygen 88.8% and hydrogen 11.2%. He considered that the atomic weight of hydrogen is 1 g, and that of oxygen 16 g.
Then, they realized that using the atomic weight of 1 g for hydrogen, the atomic weight of oxygen would be 15.9 g. This reason, among others, led to the establishment of the atomic mass of oxygen of 16 g as a reference standard for the atomic masses of the different chemical elements..
Oxygen was used as a reference standard from the end of the 19th century until 1961, when it was decided to use carbon as a reference standard for the establishment of the atomic masses of the different elements..
Before 1959, IUPAP and IUPAC used the element oxygen to define the mole as follows: 1 mole is the number of oxygen atoms present in 16 g.
Talk about 12C is to refer to carbon as a whole; or at least 98% of its essence, which is enough for such an approximation. That is why this isotope itself has no use, while the element as such, and the solids that it integrates, cover hundreds of applications..
However, it should be noted that living organisms have a special preference for this isotope over 13C; that is, the percentage of 13C or the relation 12C /13C varies according to ecosystems, regions, or animal species.
This may perhaps be because molecules with too many carbon atoms 13C, heavier, hinder or impair metabolic processes and the functioning of the body's cells; even if the percentage of 13C in living beings was just over 1%.
Therefore, the 12C is the isotope of carbon responsible for life. And the 14C the “time meter” of its remains, thanks to its radioactive decay.
Another indirect utility of 12C is to create "contrast" for the nuclear magnetic resonance spectroscopy technique of the 13C, with which the carbon structure of organic compounds can be elucidated (discovered and constructed).
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