Here are the essential concepts you must grasp in order to answer the question correctly.
Isotopes
Isotopes are variants of a chemical element that have the same number of protons but different numbers of neutrons, resulting in different mass numbers. For argon, the isotopes with mass numbers 36, 38, and 40 represent the different forms of argon found in nature. Understanding isotopes is crucial for grasping why the atomic mass is not a whole number.
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Atomic Mass
Atomic mass is the weighted average mass of an element's isotopes, measured in atomic mass units (amu). It reflects the relative abundance of each isotope in nature. Since argon has multiple isotopes, the atomic mass listed on the periodic table accounts for these variations, leading to a non-integer value.
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Weighted Average
A weighted average is a calculation that takes into account the relative importance or frequency of different values. In the case of argon, the atomic mass is calculated by multiplying the mass of each isotope by its natural abundance and then summing these products. This method results in a decimal value rather than a whole number, illustrating the concept of averaging in the context of isotopes.
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