Calculating Average Atomic Mass 2024

Front

What is average atomic mass?

Back

The weighted average of the masses of an element's isotopes, taking into account their relative abundances.

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How do you calculate average atomic mass?

Back

Multiply the mass of each isotope by its relative abundance (as a decimal), then sum these values.

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What is an isotope?

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Atoms of the same element that have the same number of protons but different numbers of neutrons, resulting in different masses.

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What is the significance of relative abundance in calculating average atomic mass?

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Relative abundance indicates how common each isotope is in nature, affecting the average atomic mass.

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If an isotope has a relative abundance of 100%, what is its contribution to average atomic mass?

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It contributes its full mass to the average atomic mass since it is the only isotope present.

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Calculate the average atomic mass of an element with isotopes: 75% of 10 amu and 25% of 12 amu.

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Average atomic mass = (0.75 * 10) + (0.25 * 12) = 10.5 amu.

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What is the average atomic mass of an element with isotopes: 50% of 20 amu and 50% of 30 amu?

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Average atomic mass = (0.50 * 20) + (0.50 * 30) = 25 amu.

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What is the average atomic mass of thallium (Tl) with isotopes Tl-203 (29.5%) and Tl-205 (70.5%)?

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Average atomic mass = (0.295 * 203) + (0.705 * 205) = 204.41 amu.

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What is the average atomic mass of an element with isotopes: 0.005% of 234.04 amu, 0.720% of 235.04 amu, and 99.275% of 238.05 amu?

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Average atomic mass = (0.00005 * 234.04) + (0.00720 * 235.04) + (0.99275 * 238.05) = 238.03 amu.

Front

What is the average atomic mass of iron (Fe) with isotopes: 6% of 54 amu, 92% of 56 amu, and 2% of 57 amu?

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Average atomic mass = (0.06 * 54) + (0.92 * 56) + (0.02 * 57) = 55.9 amu.