CHEM 001A Lecture Notes - Lecture 3: Isotope, Magnesium Oxide, Unified Atomic Mass Unit
Document Summary
Atomic mass units (amu) : unit used to express the relative masses of atoms and. 6 protons + 6 neutrons = 12 amu. Named for the english chemist john dalton. X : elemental symbol: a one or two letter symbol to identify the type of nucleus. identity of the element. atom. The 1997 mission of mars included a small robot, the sojourner, that analyzed the composition of martian rocks. magnesium oxide from a boulder was found to have the following isotopic composition: Is the average atomic mass of magnesium on mars the same as on earth (24. 31. 16 o = 15. 9948 amu (39. 9872 amu)(. 7870) + (40. 9886 amu)(. 1013) + (41. 9846 amu)(0. 1117) = 40. 31 amu. Law of definite proportions (or constant composition) : a given compound always contains its component elements in a fixed ratio (by mass) that does not depend on its source and method of preparation.
