1. What is Average Atomic Mass?

The average atomic mass (or average isotopic mass) is the weighted mean 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 weighted average formula:

Where:

• Isotope Mass — Mass of each isotope in atomic mass units (amu)
• Relative Abundance — Natural abundance of each isotope as a percentage

Explanation: The calculator sums the products of each isotope's mass and its relative abundance, then divides by the total abundance.

3. Importance of Average Mass Calculation

Details: Understanding average atomic mass is crucial for chemical calculations, stoichiometry, and understanding why atomic weights aren't whole numbers on the periodic table.

4. Using the Calculator

Tips: Enter at least one isotope mass and abundance. You can enter up to three isotopes. Abundance values should sum to 100% for accurate natural abundance calculations.

5. Frequently Asked Questions (FAQ)

Q1: Why are atomic masses not whole numbers?
A: Most elements have multiple isotopes with different masses. The atomic mass reflects the weighted average of these isotopes.

Q2: How many isotopes should I include?
A: Include all significant isotopes. For many elements, 2-3 isotopes account for nearly all natural abundance.

Q3: What if my abundance values don't sum to 100%?
A: The calculator will still work, but for natural abundance calculations, they should sum to 100% for accuracy.

Q4: Why is the average mass closer to some isotopes than others?
A: The average is weighted by abundance. More abundant isotopes influence the average more than rare ones.

Q5: Can I use this for radioactive elements?
A: Yes, but for radioactive elements, isotopic composition may vary depending on source and age.