### Formula:
$$\text{Average Atomic Mass}=\sum_{ }^{ }(\text{Isotopic Mass}\times\text{Fractional Abundance})$$
### Terminologies:
- **Average Atomic Mass** → Weighted average mass of naturally occurring isotopes of an element.
- **Isotopic Mass** → Mass of a particular isotope of an element.
- **Fractional Abundance** → Relative amount of an isotope present in nature.
### Usage:
- Used to calculate atomic mass of elements having multiple isotopes.