PERCENT COMPOSITION AND CHEMICAL FORMULAS

• • Chemical symbols - abbreviations
  • Chemical formulas - abbreviations of molecules
  • Percent Composition - ratio of the mass of an element and mass of compound x 100 - percent by mass of each element in a compound
  • Mass - either given grams or amu
  • "What is the percent composition of the compound" - calculate each element's percentage composition
• Chemical Formula is expressed in 3 ways:

  1. Empirical Formula - simplest formula (HO)
  2. Molecular Formula - determines the actual number of elements in a compound (H2O2)
  3. Structural Formula - HO--OH
• Number of moles = subscript number