To calculate the atomic mass of Carbon-12, we first need to understand the context of isotopes. Carbon has two stable isotopes: Carbon-12 (C-12) and Carbon-13 (C-13). Carbon-12 is the more abundant isotope, comprising about 98.93% of all carbon found in nature, while Carbon-13 makes up the remaining 1.07%. The atomic mass of Carbon-13 is known to be 13.00335 atomic mass units (amu).
The atomic mass of C-12 is conventionally defined to be exactly 12 amu. This standard is used because the atomic mass of elements is often expressed relative to the mass of Carbon-12, which serves as a reference point in atomic mass calculations.
In summary, the atomic mass of Carbon-12 is 12 amu, and this definition is fundamental in the field of chemistry and helps maintain consistency in the measurement of atomic masses across different elements.