Carbon-12 is used as the standard reference for relative atomic mass because it has certain properties that make it a suitable choice. Relative atomic mass is a concept that compares the masses of atoms of different elements to a reference standard. Here's why carbon-12 is commonly used for this purpose:
Abundance: Carbon-12 is the most abundant isotope of carbon, accounting for about 98.9% of all carbon atoms found in nature. This high abundance ensures that carbon-12 is readily available for use in measurements and comparisons.
Stability: Carbon-12 is a stable isotope, meaning it does not undergo radioactive decay. Its stability allows for accurate and consistent measurements over time.
Consistency: The atomic mass of an element is a weighted average of the masses of its naturally occurring isotopes, taking into account their relative abundances. Carbon-12 has a mass of exactly 12 atomic mass units (amu), which provides a convenient and consistent reference point for comparing the masses of other elements.
Universality: Carbon is a fundamental element found in all living organisms and many other substances. Using carbon-12 as the reference is practical because it allows scientists to compare atomic masses across a wide range of elements.
By defining the atomic mass unit (amu) as precisely one-twelfth the mass of a carbon-12 atom, scientists can accurately determine the relative atomic masses of other elements and isotopes. This choice of carbon-12 as the reference standard provides a consistent basis for atomic mass measurements in the field of chemistry.