1. What is Average Atomic Mass?

The average atomic mass is the weighted average of the atomic masses of all naturally occurring isotopes of an element, taking into account their relative abundances. It's the value you see on the periodic table for each element.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• Isotope Mass — Mass of each isotope in atomic mass units (u)
• Abundance — Natural abundance of each isotope in percentage (%)
• The sum of all abundances must equal 100%

Explanation: Each isotope's contribution to the average mass is proportional to its natural abundance.

3. Importance of Average Atomic Mass

Details: The average atomic mass is crucial for chemical calculations, stoichiometry, and understanding the composition of elements in nature. It affects molecular weights and all mass-related calculations in chemistry.

4. Using the Calculator

Tips: Enter the mass and natural abundance for each isotope. Add as many isotopes as needed. The total abundance must equal 100%. Masses should be in atomic mass units (u), abundances in percent (%).

5. Frequently Asked Questions (FAQ)

Q1: Why doesn't the average mass equal any of the isotope masses?
A: The average is a weighted value that accounts for all naturally occurring isotopes and their relative abundances.

Q2: What if my abundances don't add up to exactly 100%?
A: The calculator requires the total to be 100% within a small margin of error. Natural abundances typically sum to 100%.

Q3: How precise should my isotope masses be?
A: For most purposes, 4-6 decimal places are sufficient, as this matches the precision of most published isotope masses.

Q4: Can I use this for radioactive elements?
A: For elements with very short-lived isotopes, the concept of "natural abundance" may not apply well.

Q5: Why is the average mass important in chemistry?
A: It determines the molar mass of elements, which is essential for all stoichiometric calculations and chemical formulas.