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Ch.2 - Atoms & Elements
Tro - Chemistry: A Molecular Approach 4th Edition
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Tutti i libri di testoTro 4th EditionCh.2 - Atoms & ElementsProblema 76
Capitolo 2, Problema 76

An element has four naturally occurring isotopes with the masses and natural abundances given here. Find the atomic mass of the element and identify it.
Isotope Mass (amu) Abundance (%)
1 135.90714 0.19
2 137.90599 0.25
3 139.90543 88.43
4 141.90924 11.13

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First, we need to understand that the atomic mass of an element is the weighted average of the masses of its isotopes. The weight of each isotope is its abundance. So, we will multiply the mass of each isotope by its abundance to get a 'weighted' mass.
Next, convert the abundances from percentages to fractions by dividing each by 100. For example, the abundance of the first isotope would be 0.19/100 = 0.0019.
Then, multiply the mass of each isotope by its corresponding abundance (now in fraction form). For example, the weighted mass of the first isotope would be 135.90714 * 0.0019.
Add up all the weighted masses. This will give you the atomic mass of the element.
Finally, compare the calculated atomic mass with the atomic masses of known elements to identify the element. You can use a periodic table for this comparison.

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Isotopes

Isotopes are variants of a chemical element that have the same number of protons but different numbers of neutrons, resulting in different atomic masses. For example, carbon has isotopes like carbon-12 and carbon-14. Understanding isotopes is crucial for calculating the average atomic mass of an element based on its isotopic composition.
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Isotopes

Atomic Mass Calculation

The atomic mass of an element is calculated by taking the weighted average of the masses of its isotopes, considering their natural abundances. This is done using the formula: Atomic Mass = (mass1 × abundance1) + (mass2 × abundance2) + ... + (massn × abundancen). This concept is essential for determining the overall atomic mass from the provided isotopic data.
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Calculating Atomic Mass

Natural Abundance

Natural abundance refers to the relative percentage of each isotope of an element found in nature. It is expressed as a percentage and is critical for accurately calculating the average atomic mass. In the given question, the abundances of the isotopes must be used to weight their respective masses in the atomic mass calculation.
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Nature of Energy
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