The average atomic mass of iron, often represented by the symbol Fe, is approximately 55.85 atomic mass units (amu).
This value is a weighted average that takes into account the relative abundances of the various isotopes of iron found in nature. Iron has several isotopes, with iron-56 being the most abundant, making up about 91.75% of naturally occurring iron. The presence of other isotopes, such as iron-54, iron-57, and iron-58, contributes to the overall average but to a lesser extent.
Understanding atomic mass is crucial in chemistry, as it helps in calculating the amount of substance needed in chemical reactions. The average atomic mass is not a whole number because it reflects the proportion of each isotope’s mass, weighted by its natural abundance.