1. What is Atomic Mass?

The atomic mass (also called relative atomic mass) of an element is the weighted average of the masses of its naturally occurring isotopes, taking into account their relative abundances. It's expressed in atomic mass units (u).

2. How Does the Calculator Work?

The calculator uses the atomic mass formula:

Where:

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

Explanation: The calculator normalizes the abundances to sum to 100% if they don't already, then calculates the weighted average of the isotope masses.

3. Importance of Atomic Mass Calculation

Details: Atomic mass is fundamental in chemistry for stoichiometric calculations, determining molecular weights, and understanding chemical reactions. It's essential for laboratory work and industrial chemical processes.

4. Using the Calculator

Tips: Enter each isotope's mass and relative abundance. You can add multiple isotopes. Values must be positive numbers (mass > 0, abundance between 0-100).

5. Frequently Asked Questions (FAQ)

Q1: Why is atomic mass not a whole number?
A: Atomic mass is a weighted average of different isotopes, which have different masses and occur in different natural abundances.

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

Q3: How precise are typical atomic mass values?
A: Modern atomic mass values are typically reported to 4-6 decimal places, as measured by mass spectrometry.

Q4: Why do we use weighted average instead of simple average?
A: A weighted average accounts for the fact that some isotopes are much more common than others in nature.

Q5: Where can I find isotope abundance data?
A: The IUPAC publishes authoritative isotope abundance data in the Periodic Table of the Elements.