LT II chap 4

• Important compounds

  • water (H2O)
  • sodium chloride (NaCl)
  • Carbon dioxide (CO2)
  • Sulfuric acid (H2SO4)
  • ethanol (C2H6O)
  • ammonia (NH3)
  • methane (CH4)
• Molecular formula


  Indicates actual number of atoms of each element in 1 molecule
• Empirical formula


  Simplest whole number ratio of atoms of each element present in a chemical compound
• Molecular and empirical formulas consist of non-metallic and/or metallic elements represented by their relative numbers present in the simplest possible whole number ratio
• Molecular and empirical formulas consist of metallic, non-metallic, and/or metalloid elements
• Relative atomic mass


  Average mass of atoms of an element
• Relative formula mass


  Sum of the relative atomic masses of the elements in a compound
• Mole


  Unit used to measure amount of substance
• Avogadro's number is 6.022 x 10^23
• In chemical reactions, matter is neither created nor destroyed. The total mass of all products is equal to the total mass of all reactants.
• All samples of a given compound, regardless of source or preparation, contain the same elements in identical proportions by mass.
• Dalton's atomic theory


  • Each element is composed of extremely small particles called atoms
  • All atoms of a given element are identical in mass and other properties, but atoms of one element are different from atoms of all other elements
  • Atoms of one element cannot change into atoms of a different element by chemical reactions
  • Atoms are neither created nor destroyed in chemical reactions, but they change their way of connecting with other atoms
  • Compounds are formed when atoms of more than one element combine, and a given compound always contains the same kinds of atoms in the same whole number ratio
• Chemical equation


  Representation of a chemical reaction using chemical formulas
• Combustion


  Reaction of a substance with oxygen, usually yielding carbon dioxide and water
• Complete combustion of hydrocarbon compounds yields carbon dioxide and water
• Mass (m)


  Measured in grams (g)
• Amount of substance (n)

  Measured in moles (mol)
• Molar mass (M)


  Mass per mole of a substance, measured in grams per mole (g/mol)