Understanding Relative Mass
You'll need to master several key definitions that all relate to comparing masses against carbon-12 as the standard. Think of carbon-12 as the "ruler" we use to measure everything else in chemistry.
Relative isotopic mass is simply the mass of one specific isotope compared to 1/12th of a carbon-12 atom. Meanwhile, relative atomic mass is more complex - it's the weighted average mass of all an element's isotopes, taking into account how common each one is.
To calculate relative atomic mass, use this formula: ((Isotopic mass × percentage abundance) + (Isotopic mass × percentage abundance))/100. You're basically finding the average, but giving more weight to the isotopes that appear more frequently.
Quick tip: Remember that relative atomic mass isn't just a simple average - it's weighted by how abundant each isotope is in nature!
