Assertion: deuterium | /r/HasAspect | a mass of 2.014 u
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Source sentences:
text: The reason deuterium has a distinct chemical symbol may be its large mass difference with protium (¹H); deuterium has a mass of 2.014 u, compared to the mean hydrogen atomic weight of 1.007947 u, and protium's mass of 1.007825 u.