Isotopes and Average Atomic Mass

Front

What is an isotope?

Back

Isotopes are variants of a chemical element that have the same number of protons but different numbers of neutrons, resulting in different atomic masses.

Front

How is average atomic mass calculated?

Back

Average atomic mass is calculated by taking the weighted average of the atomic masses of an element's isotopes, based on their relative abundances.

Front

What is the significance of the average atomic mass in chemistry?

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The average atomic mass helps predict the behavior of elements in chemical reactions and is used in stoichiometry to calculate the amounts of reactants and products.

Front

What does it mean if an isotope is more abundant?

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If an isotope is more abundant, it means that a larger percentage of the element's atoms are that particular isotope, which influences the average atomic mass.

Front

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

Back

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 mass 20 amu and 50% of mass 22 amu?

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Average atomic mass = (0.50 * 20) + (0.50 * 22) = 21 amu.

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What is the average atomic mass of chlorine if it has isotopes 35Cl (75%) and 37Cl (25%)?

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Average atomic mass = (0.75 * 35) + (0.25 * 37) = 35.5 amu.

Front

What is the formula for calculating average atomic mass?

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Average Atomic Mass = Σ (isotope mass × fractional abundance) for all isotopes.

Front

If an element has two isotopes, A and B, with masses 10 amu and 12 amu, and abundances 80% and 20%, what is the average atomic mass?

Back

Average atomic mass = (0.80 * 10) + (0.20 * 12) = 10.4 amu.

Front

What is the average atomic mass of an element with isotopes: 90% of mass 14 amu and 10% of mass 16 amu?

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Average atomic mass = (0.90 * 14) + (0.10 * 16) = 14.2 amu.