Many elements have fractional atomic masses. This is because:
Correct answer: D. Atomic masses are average masses of isotopes proportional to their abundance
- A. Mass of atom is itself reactional
- B. Atomic masses are average masses of isobars
- C. Atomic masses are average masses of isotopes
- D. Atomic masses are average masses of isotopes proportional to their abundance
Explanation
Atomic masses are typically reported as weighted averages that take into account the abundance of each isotope of an element. Most elements exist as a mixture of isotopes, and these isotopes have different masses. The atomic mass of an element listed on the periodic table is a weighted average of the masses of its naturally occurring isotopes. The weighting is based on the abundance of each isotope in nature. Since isotopes have different masses, the atomic mass is not a whole number, and it may appear as a fractional value.
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About Fundamental Concepts of Chemistry
Mole calculations connect mass, number of particles and Avogadro's number, while balanced equations provide the mole ratios used in stoichiometry. Questions cover limiting and excess reactants, theoretical yield and percentage yield, including identifying which reactant is consumed first and comparing the actual product with the maximum possible product.
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