Practice question · Multiple choice
The periodic table lists the atomic mass of chlorine as 35.45 u, yet no single chlorine atom possesses this mass. What does this distinction imply when calculating macroscopic versus microscopic quantities of matter?
Hints
- What does the periodic table's value represent compared to the contents of an actual reaction flask?
- Can an individual nucleus contain a fractional combination of protons and neutrons?
Show the answer
A. The tabular value applies only to bulk samples containing isotopic mixtures
Why
Non-integer masses in bulk data arise strictly from mixed populations of discrete isotopes rather than fractional nucleons. Macroscopic measurements reflect these statistical blends, whereas single-atom interactions depend entirely on specific, integer-valued isotope masses.
Practise Atomic Models and Isotopes
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