1. What is Average Atomic Mass?

The average atomic mass of an element is the weighted average of the atomic masses of its naturally occurring isotopes, 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 — The mass of each isotope in atomic mass units (amu)
• Fractional Abundance — The natural abundance of each isotope as a decimal (must sum to 1)

Explanation: The calculator sums the products of each isotope's mass and its relative abundance to determine the weighted average mass.

3. Importance of Average Atomic Mass

Details: Average atomic mass is crucial for chemical calculations, stoichiometry, and understanding element properties. It explains why atomic weights on the periodic table aren't whole numbers.

4. Using the Calculator

Tips:

• Enter isotope masses in atomic mass units (amu)
• Enter fractional abundances as decimals between 0 and 1 (must sum to 1)
• Click "Add Another Isotope" for elements with multiple isotopes
• Ensure the total abundance equals exactly 1

5. Frequently Asked Questions (FAQ)

Q1: Why isn't the average atomic mass a whole number?
A: Most elements have multiple isotopes with different masses. The average is weighted by their natural abundances.

Q2: What's the difference between mass number and average atomic mass?
A: Mass number is the sum of protons and neutrons in a specific isotope (always a whole number). Average atomic mass is the weighted average of all naturally occurring isotopes.

Q3: How precise should my isotope masses be?
A: For most calculations, 4 decimal places (e.g., 15.9949 amu for oxygen-16) provides sufficient accuracy.

Q4: What if my abundances don't sum to exactly 1?
A: The calculator will show an error. Normalize your abundances so they sum to 1 (divide each by the total).

Q5: Can I use percentage abundances instead of fractions?
A: Yes, but convert them to fractions first (e.g., 75% = 0.75).