1. What is Atomic Mass?

Atomic mass is the weighted average mass of an element's isotopes, taking into account the natural abundance of each isotope. It's measured in atomic mass units (amu) and appears on the periodic table for each element.

2. How Does the Calculator Work?

The calculator uses the atomic mass equation:

Where:

• \( fraction_i \) — Fractional abundance of isotope i (dimensionless)
• \( mass_i \) — Mass of isotope i (amu)

Explanation: The equation calculates a weighted average where each isotope's contribution is proportional to its natural abundance.

3. Importance of Atomic Mass Calculation

Details: Atomic mass is fundamental in chemistry for stoichiometric calculations, determining molar masses, and understanding isotopic composition of elements.

4. Using the Calculator

Tips: Enter the fractional abundance (between 0 and 1) and mass (in amu) for each isotope. Click "Add Another Isotope" for elements with multiple isotopes. The sum of all fractions should equal 1 for accurate results.

5. Frequently Asked Questions (FAQ)

Q1: What's the difference between atomic mass and atomic weight?
A: They are essentially the same - both refer to the weighted average mass of an element's isotopes. "Atomic weight" is the older term.

Q2: Why is atomic mass not a whole number?
A: Most elements have multiple isotopes with different masses. The atomic mass reflects the average of these isotopes based on their natural abundance.

Q3: How do I get the fractional abundances?
A: Fractional abundances are typically found in chemistry reference materials or can be calculated by dividing percentage abundance by 100.

Q4: What if my fractions don't add up to exactly 1?
A: The calculator will still work, but for real-world accuracy, the sum should be 1 (or 100% if using percentages).

Q5: Why is carbon-12 used as the standard for atomic mass?
A: Carbon-12 was chosen as the reference (defined as exactly 12 amu) because it's a stable, abundant isotope that forms many compounds.