Formula

• Relative Formula Mass

  Sum of all of the the Relative Atomic Masses of all the atoms in that compounds Molecular Formula
• Empirical Formula

  simplest whole number ratio of atoms or ions of each element in a compound
• Calculating Relative Formula Mass


  1. (no. of atoms) x (Relative atomic mass)
  2. Repeat for every element in the compound
  3. Add together
• Calculating Empirical Formula (when given mass)

  Layout:

  1. mass
  2. RAM
  3. mass ÷ RAM
  4. ÷ by smallest value
  5. Round and put in no. ratio
  6. Put in Molecular Formula
• Mols

  Number of moles of a substance = mass of a substance (g) ÷ Ar (RAM) or Mr (RFM)