CHE 2A Lecture Notes - Lecture 2: Chemical Formula, Sodium Chloride, Hydrogen Peroxide
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CHE 2A Full Course Notes
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Che2a lecture 2 counting and weighing atoms and molecules; chemical compounds and chemical formulas. Atomic mass: weighted average mass of its isotopes, does not refer to the mass of specific atom unless the element is monoisotopic (having only one isotope found in nature; 26 elements) Amount: refers to the number of atoms, molecules, or ions. Quantity: refers to mass of matter in a sample, usually expressed in grams of kilograms. Quantity same quantities, different amounts same amounts, different quantities. Counting by weighing: to find the number of molecules in a sample, divide the mass of the sample by the mass of one molecule. Dozen: one dozen items is 12 identical items. Ionic or covalent compound is the mass of the chemical unit in amu. Molecular compound: made up of discrete units called molecules, molecules, consists of a certain number of atoms held together with strong covalent bonds. Ionic network compounds: made up of ions.