QQuestionChemistry
QuestionChemistry
Why is the atomic mass of iron, 55.845 amu , most similar to the mass of iron- 56, yet less than 56 amu ?
The atomic mass is the simple average of the masses of the two most abundant isotopes. Iron- 56 is the most abundant isotope, so the atomic mass of iron is most similar to the mass of iron- 56. The second most abundant isotope is iron- 54, which reduces the atomic mass to less than 56 amu .
The atomic mass is the weighted average of the masses of the two most abundant isotopes. Iron- 56 is the most abundant isotope, so the atomic mass of iron is most similar to the mass of iron- 56. The second most abundant isotope is iron- 54, which reduces the atomic mass to less than 56 amu .
The atomic mass is the weighted average of the masses of all of the isotopes. Iron- 56 is the most abundant isotope, so the atomic mass of iron is most similar to the mass of iron- 56. The second most abundant isotope is iron- 54, which reduces the atomic mass to less than 56 amu .
The atomic mass is the simple average of the masses of all of the isotopes. Iron- 56 is the most abundant isotope, so the atomic mass of iron is most similar to the mass of iron- 56. The second most abundant isotope is iron- 54, which reduces the atomic mass to less than 56 amu .
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Step 1:: Understand the concept of atomic mass and isotopes.
The atomic mass of an element is a weighted average of the masses of its isotopes, with the weighting being proportional to the isotopes' abundance. Isotopes are variants of an element that have different numbers of neutrons and, consequently, different masses.
Step 2:: Identify the relationship between atomic mass and isotopes' masses and abundances.
Even though iron- 56 is the most abundant isotope, the atomic mass of iron is not exactly 56 amu. This is because the atomic mass is a weighted average, and the second most abundant isotope, iron- 54, reduces the average value.
Step 3:: Analyze the given statement about the atomic mass of iron.
The atomic mass of iron is 55.845 amu, which is most similar to the mass of iron- 56 (55.9349 amu) but less than 56 amu. This is due to the weighted average effect of the second most abundant isotope, iron- 54 (53.9396 amu).
Step 4:: Summarize the explanation.
The atomic mass of iron is most similar to the mass of iron- 56 because iron- 56 is the most abundant isotope. However, the atomic mass is less than 56 amu due to the contribution of the second most abundant isotope, iron- 54, which reduces the average value through the weighted average calculation.
Final Answer
The atomic mass of iron is most similar to the mass of iron- 56 (55.9349 amu) because iron- 56 is the most abundant isotope. However, the atomic mass is less than 56 amu (55.845 amu) due to the contribution of the second most abundant isotope, iron- 54 (53.9396 amu), which reduces the average value through the weighted average calculation.
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