Atomic mass of an element is

Options

A. Actual mass of one atom of the element
B. Relative mass of an atom of the element
C. Average relative mass of different atoms of the element
D. Always a whole number

Answer

**Step-by-Step Solution:**

1. **Understanding Atomic Mass**: Atomic mass is a measure of the mass of an atom, typically expressed in atomic mass units (amu). It reflects the total number of protons and neutrons in the nucleus of an atom.

2. **Definition of Atomic Mass**: The atomic mass of an element is defined as the average mass of the atoms of an element, taking into account the relative abundances of its isotopes.

3. **Average Atomic Mass**: To calculate the average atomic mass, we consider the isotopes of the element and their respective masses and natural abundances. The formula used is:
\[ \text{Average Atomic Mass} = \sum \left( \text{(mass of isotope)} \times \text{(abundance of isotope)} \right) \]
where the sum is taken over all isotopes of the element.

4. **Relative Mass**: Atomic mass is often expressed as a relative mass compared to the mass of carbon-12, which is defined as exactly 12 amu. This means that atomic mass is a dimensionless quantity that compares the mass of an atom to that of carbon-12.

5. **Conclusion**: Therefore, the atomic mass of an element is best defined as the average relative mass of the different isotopes of that element.

**Final Answer**: The atomic mass of an element is defined as the average relative mass of the different isotopes of that element.

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