Atomic mas 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 numberEx

Answer

To determine the atomic mass of an element, we follow these steps:

### Step-by-Step Solution:

1. **Understanding Atomic Mass**:
- Atomic mass is defined as the average relative mass of an element's isotopes, weighted by their natural abundance.

2. **Identify Isotopes**:
- For example, consider the element Carbon. It has isotopes such as Carbon-12 (C-12) and Carbon-13 (C-13).

3. **Obtain Masses of Isotopes**:
- The mass of Carbon-12 is approximately 12 atomic mass units (amu), and the mass of Carbon-13 is approximately 13 amu.

4. **Determine Natural Abundance**:
- Next, we need to know the natural abundance of these isotopes. For Carbon, C-12 makes up about 98.89% of natural carbon, while C-13 makes up about 1.11%.

5. **Calculate Weighted Average**:
- The atomic mass can be calculated using the formula:
\[ \text{Atomic Mass} = \left( \text{Fraction of C-12} \times \text{Mass of C-12} \right) + \left( \text{Fraction of C-13} \times \text{Mass of C-13} \right) \]
- Plugging in the values:
\[ \text{Atomic Mass} = \left( 0.9889 \times 12 \right) + \left( 0.0111 \times 13 \right) \]

6. **Perform the Calculation**:
- Calculate each term:
- For C-12: \( 0.9889 \times 12 = 11.8668 \)
- For C-13: \( 0.0111 \times 13 = 0.1443 \)
- Now add these values together:
\[ \text{Atomic Mass} = 11.8668 + 0.1443 = 12.0111 \text{ amu} \]

7. **Conclusion**:
- Therefore, the atomic mass of Carbon is approximately 12.01 amu.