Textbook Question
Argon has three naturally occurring isotopes, with mass numbers 36, 38, and 40.d. Why is the atomic mass of argon listed on the periodic table not a whole number?
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4. Atoms and Elements
Atomic Mass (Simplified)
Multiple Choice
In the simplified atomic mass scale, what is the mass of one atom of carbon-12?
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Verified step by step guidance1
Understand that the atomic mass unit (amu) is defined based on the carbon-12 isotope, where one atom of carbon-12 is assigned exactly 12 amu by definition.
Recall that the atomic mass scale is a relative scale where the mass of one atom of carbon-12 is the standard reference point.
Recognize that the mass of one atom of carbon-12 is therefore exactly 12 amu, which means it serves as the baseline for measuring atomic masses of other elements.
Note that other values like 6 amu, 1 amu, or 24 amu do not correspond to the mass of a single carbon-12 atom in this scale.
Conclude that the mass of one atom of carbon-12 in the simplified atomic mass scale is 12 amu.
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