1. What is Average Atomic Mass?

The average atomic mass is the weighted average 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:

• \( \text{abundance} \) — Natural abundance of the isotope (%)
• \( \text{isotope} \) — Atomic mass of the isotope (amu)
• The sum is over all naturally occurring isotopes

Explanation: Each isotope's contribution is weighted by its natural abundance, then summed and divided by 100 (since abundances are percentages).

3. Importance of Average Atomic Mass

Details: The average atomic mass is crucial for chemical calculations, stoichiometry, and understanding element properties. It differs from mass number because it accounts for all naturally occurring isotopes.

4. Using the Calculator

Tips: Enter at least one isotope mass and its abundance. You can enter up to three isotopes. Ensure abundances sum to approximately 100% for accurate results.

5. Frequently Asked Questions (FAQ)

Q1: Why don't abundances always sum to exactly 100%?
A: Natural variations and measurement uncertainties can cause slight deviations from 100%.

Q2: How many isotopes can an element have?
A: Elements can have from 1 (monoisotopic) to over 30 isotopes (e.g., tin has 10 stable isotopes).

Q3: Why is average atomic mass not a whole number?
A: It's a weighted average of different isotope masses, which often includes fractional atomic mass units.

Q4: Can I use this for radioactive elements?
A: For elements with very long-lived isotopes (like uranium), yes. For highly radioactive elements, the concept is less meaningful.

Q5: How precise should my inputs be?
A: For most purposes, 4 decimal places for mass and 2 for abundance are sufficient.