Why Aren't All Atomic Masses Whole Numbers?

The video explains that atomic masses are not always whole numbers due to isotopes, which are atoms of the same element with different numbers of neutrons. Using chlorine as an example, the video shows how the relative abundance of isotopes affects the calculation of relative atomic mass. A formula is provided to calculate this weighted mean mass. Another example with bromine is given to reinforce the concept. The video concludes by emphasizing that the relative atomic mass is a weighted mean of isotopes, explaining why these values are not whole numbers.

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