Average Atomic Mass Formula:
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Definition: Average atomic mass is the weighted average of the atomic masses of all naturally occurring isotopes of an element.
Purpose: It helps chemists and physicists understand the composition of elements and perform accurate calculations in chemical reactions.
The calculator uses the formula:
Where:
Explanation: The formula calculates a weighted average based on the relative abundance (ratio terms) of each isotope.
Details: The average atomic mass appears on the periodic table and is crucial for stoichiometric calculations in chemistry.
Tips: Enter the ratio terms (relative abundances) and atomic masses for both isotopes. The ratio terms don't need to sum to 100 - they represent relative proportions.
Q1: What are atomic mass units (u)?
A: 1 atomic mass unit is defined as 1/12th the mass of a carbon-12 atom (approximately 1.6605 × 10⁻²⁷ kg).
Q2: How do I find isotope ratios?
A: Isotope ratios are typically determined through mass spectrometry and can be found in scientific literature.
Q3: Can I calculate for more than two isotopes?
A: Yes, simply extend the formula: (m×a + n×b + p×c + ...)/(m + n + p + ...).
Q4: Why is the average not just a simple mean?
A: Because different isotopes occur in different natural abundances, so we need a weighted average.
Q5: How precise should my inputs be?
A: Use as many decimal places as available, especially for the atomic masses which are known to high precision.