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Atomic Weight Formula:
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Atomic weight (also called relative atomic mass) is the average mass of atoms of an element, calculated using the relative abundance of isotopes in a naturally occurring element. It accounts for the fact that most elements exist as mixtures of isotopes with different masses.
The calculator uses the atomic weight formula:
Where:
Explanation: The formula calculates the weighted average of all naturally occurring isotopes of an element, where the weights are the relative abundances of each isotope.
Details: Atomic weight is fundamental in chemistry for stoichiometric calculations, determining molecular weights, and understanding chemical reactions. It's essential for laboratory work, industrial processes, and educational purposes.
Tips: Enter the percentage abundance and mass for each isotope. The sum of all percentages must equal 100%. You can calculate for elements with 2 or 3 isotopes. Mass should be entered in atomic mass units (u).
Q1: What is the difference between atomic weight and atomic mass?
A: Atomic mass refers to the mass of a single atom, while atomic weight is the weighted average of all naturally occurring isotopes of an element.
Q2: Why do percentages need to sum to 100%?
A: The percentages represent the relative abundance of all isotopes of the element in nature, so they must account for 100% of the element's composition.
Q3: What are atomic mass units (u)?
A: Atomic mass unit is defined as 1/12th the mass of a carbon-12 atom, approximately 1.66053906660 × 10⁻²⁷ kilograms.
Q4: Can I calculate for elements with more than 3 isotopes?
A: This calculator supports up to 3 isotopes. For elements with more isotopes, you would need to extend the calculation manually using the same formula.
Q5: Why are atomic weights not whole numbers?
A: Atomic weights are averages of different isotopes with different masses, and the abundance of each isotope affects the final weighted average.