Relative formula mass

• The A, values for elements are given in the periodic table
• Relative formula mass

  The sum of the relative atomic masses of the atoms in a substance
• Steps to calculate M.

  • Work out how many atoms of each element there are in the chemical formula
  • Add together the A, values for all the atoms of each element present
• Atoms have very little mass so their relative atomic masses are used
• M.


  Relative formula mass of a substance
• Relative atomic mass


  The relative mass of an element's atoms compared to the mass of a carbon-12 atom
• A,

  Relative atomic mass of an element
• M, of CO₂ 12+16+16=44