CHEM 103 Chapter Notes - Chapter 2: Ionic Compound, Mass Spectrometry, Relative Atomic Mass
14 Sep 2016
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Chapter 2 notes, sections 2. 3-2. 7 (skipping 4b and 7b) Unified atomic mass ( u or amu ) = 1/12 the mass of an atom of carbon-12, the unit for quantifying the atomic masses of atoms and molecules. Both the neutron and the proton weigh roughly 1 amu, while the electron weighs nearly nothing (0. 000548579 amu) The relative masses of atoms can be determined very precisely by using an instrument called a mass spectrometer. Mass spectrum graphs show the abundance of an element"s isotopes, with spikes signaling where main percentages of that element"s variations of masses occur. Mass spectronomy analysis reveals that not all atoms of the same element have the same mass. Isotopes = atoms of the same element that have different numbers of neutrons. We usually refer to a particular isotopes by their mass number. Ex: the isotope of uranium with a mass number of 238 is called uranium-238.
