1. What is Atomic Mass?

Atomic mass is the weighted average mass of all naturally occurring isotopes of an element, measured in atomic mass units (amu). It takes into account both the mass and relative abundance of each isotope.

2. How to Calculate Atomic Mass

The atomic mass is calculated using the formula:

Where:

• \( \text{Isotope Mass} \) — Mass of each isotope in atomic mass units (amu)
• \( \text{Abundance} \) — Relative abundance of each isotope as a fraction
• \( \sum \) — Summation of all isotope contributions

Explanation: The atomic mass is a weighted average where more abundant isotopes contribute more significantly to the overall mass.

3. Importance of Atomic Mass Calculation

Details: Atomic mass is fundamental in chemistry for stoichiometric calculations, determining molecular weights, and understanding chemical reactions and properties.

4. Using the Calculator

Tips: Enter the mass of each isotope in amu and their abundances as percentages. The calculator will convert percentages to fractions and compute the weighted average atomic mass.

5. Frequently Asked Questions (FAQ)

Q1: What is the difference between atomic mass and mass number?
A: Mass number is the total number of protons and neutrons in a specific isotope, while atomic mass is the weighted average of all naturally occurring isotopes.

Q2: Why is atomic mass not a whole number?
A: Atomic mass is a weighted average of different isotopes with different masses, so it typically results in a decimal value.

Q3: How do I convert abundance percentage to fraction?
A: Divide the percentage by 100. For example, 75% abundance becomes 0.75 as a fraction.

Q4: What if an element has more than two isotopes?
A: The same formula applies - simply add more terms for each additional isotope (mass × abundance).

Q5: Why is carbon-12 used as the standard for atomic mass?
A: Carbon-12 was chosen as the reference standard because it's a stable isotope and provides a consistent basis for mass measurements.