CHEM 1040 Chapter Notes - Chapter 2: Numeral Prefix, Electron Rest Mass, Cadmium Iodide
12 Sep 2016
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2. 1 elements, compounds, and mixtures: an atomic overview. Elements and compounds are called substances, matter with fixed compositions: mixtures are not substances because they have a variable composition. Molecule an independent structure of two or more atoms bonded together: oxygen is a diatomic (tow-atom) molecule. 2. 2 the observations that led to an atomic view of matter. Law of mass conservation the total mass of substances does not change during a chemical reaction: matter cannot be created or destroyed, mass before and after a reaction is exactly the same. Mass fraction = mass of element in the compound / mass of compound: percent by mass: the fraction by mass expressed as a percentage (multiplied by. Mass percent = mass fraction x 100: each compound has a fixed mass fraction and mass percent, mass of element = mass of compound in sample x mass of element in compound / mass of compound. 2. 4 the observations that led to the nuclear atom model.
