The Precise Weight of a Mole of Some Pure Elements

question 45

Multiple Choice

The precise weight of a mole of some pure elements like silicon (Si) can vary slightly from the standard atomic mass, or even from sample to sample. Why?

• A) The element may undergo radioactive decay.
• B) The element may react with itself and gain or lose subatomic particles.
• C) The atoms of the element form chemical bonds with each other, and that changes the weight of the element.
• D) The element may have multiple stable isotopes, and the isotopic composition may vary from sample to sample.
• E) The amount of energy absorbed by the element affects the mass of its electrons, and thus the atomic mass can vary slightly.

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