Why do atomic masses of most of the elements in atomic mass units involve fractions?

Explanation

To understand why the atomic masses of most elements in atomic mass units involve fractions, we can break down the explanation into a series of steps:

### Step-by-Step Solution:

1. **Definition of Atomic Mass:**
- Atomic mass is defined as the average mass of an element's atoms, measured in atomic mass units (amu).

2. **Isotopes of Elements:**
...