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Atomic Mass Equation:
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The Atomic Mass Calculator computes the weighted average mass of an element's isotopes based on their natural abundances. This value appears on the periodic table and is essential for chemical calculations.
The calculator uses the atomic mass equation:
Where:
Explanation: The equation calculates a weighted average where each isotope's contribution is proportional to its natural abundance.
Details: Accurate atomic mass is crucial for stoichiometric calculations, determining molar masses, and understanding chemical reactions at the molecular level.
Tips: Enter isotope masses in atomic mass units (amu) and abundances as percentages. The sum of all abundances must equal 100%. You can calculate with 2 or 3 isotopes.
Q1: Why is atomic mass not a whole number?
A: Atomic mass is a weighted average of all naturally occurring isotopes, accounting for their different masses and 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 isotopes.
Q3: How accurate are natural abundance values?
A: Natural abundances are experimentally determined and typically accurate to 2-4 significant figures, though they can vary slightly in different samples.
Q4: Can I use this for radioactive elements?
A: For elements with very short-lived isotopes, the atomic mass may represent the most stable isotope rather than a true weighted average.
Q5: Why does my calculation differ slightly from periodic table values?
A: Minor differences may occur due to rounding of isotope masses or abundances, or variations in natural samples.