1. What is Average Atomic Mass?

The average atomic mass is the weighted average of the 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 average mass formula:

Where:

• \( Mass_i \) — Mass of isotope i (in atomic mass units, amu)
• \( Abundance_i \) — Natural abundance of isotope i (as a fraction)

Explanation: The calculator sums the products of each isotope's mass and its fractional abundance (percentage divided by 100).

3. Importance of Average Mass Calculation

Details: The average atomic mass is crucial in chemistry for stoichiometric calculations, determining molar masses of compounds, and understanding elemental properties.

4. Using the Calculator

Tips: Enter each isotope's mass in atomic mass units (amu) and its natural abundance as a percentage. The total of all abundances must equal 100%. You can add or remove isotope fields as needed.

5. Frequently Asked Questions (FAQ)

Q1: Why is the average mass not just the sum divided by number of isotopes?
A: Because isotopes occur with different natural abundances, we must weight each isotope's mass by how common it is.

Q2: How precise should my mass and abundance values be?
A: For most calculations, 4-5 significant figures are sufficient. High-precision work may require more digits.

Q3: Can I use this for radioactive isotopes?
A: Yes, but only if you're calculating for a specific sample at a specific time, as radioactive isotopes decay over time.

Q4: What if my abundances don't add up to exactly 100%?
A: The calculator will show an error. Natural abundances should always sum to 100% within small measurement errors.

Q5: Why do some elements have more isotopes than others?
A: The number of stable isotopes depends on nuclear stability, which varies with proton and neutron numbers.