The relative atomic masses of many elements are not whole numbers because

Options

A. they cannot be determined very accurately
B. the atoms ionize during the determinations
C. of the existence of isotopes
D. of the presence of impurities

Answer

To answer the question "The relative atomic masses of many elements are not whole numbers because...", we can break down the explanation into the following steps:

### Step 1: Understanding Relative Atomic Mass
Relative atomic mass is defined as the weighted average mass of an atom of an element compared to 1/12th the mass of a carbon-12 atom.

### Step 2: The Role of Isotopes
Elements can exist in different forms called isotopes. Isotopes are atoms of the same element that have the same number of protons but different numbers of neutrons. This means they have different masses.

### Step 3: Isotopic Composition
The relative atomic mass of an element is calculated based on the isotopic composition of the sample. This means that the relative abundance of each isotope in a sample affects the overall average atomic mass.

### Step 4: Variability in Isotopic Abundance
The isotopic composition can vary depending on the source of the element. Different natural sources may have different ratios of isotopes, leading to variations in the calculated relative atomic mass.

### Step 5: Conclusion
Because of the presence of multiple isotopes and their varying abundances in different samples, the relative atomic masses of many elements are not whole numbers.

### Final Answer
The relative atomic masses of many elements are not whole numbers because they are calculated based on the weighted average of the atomic masses of isotopes, which vary in abundance depending on the source of the element.

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