Relative formula mass

• How can we find the mass number of any element?

  By looking in the top left corner of its nuclear symbol
• What does the mass number represent?

  The number of protons plus the number of neutrons in the nucleus
• What is relative atomic mass?

  Simplification of the mass of an atom. Relative atomic mass is the mean relative mass of the isotopes of an element. The relative atomic mass of an element compares the mass of an atom of an element with the mass of an atom of carbon. Denoted with Ar
• What is relative formula mass?

  The relative formula mass of a compound is the sum of all the masses of all elements in the chemical formula
• How do you calculate the relative formula mass of a compound?

  By adding together the relative atomic masses of all the atoms in its molecular formula
• What are the steps to calculate the relative formula mass of a compound?

  1. Identify the molecular formula of the compound.
  2. Find the relative atomic mass (ar) of each element from the periodic table.
  3. Multiply the ar of each element by the number of atoms of that element in the formula.
  4. Sum all the values to get the relative formula mass (mr).
• What is the process to find the percentage mass of an element in a compound?

  1. Identify the relative atomic mass (ar) of the element.
  2. Multiply the ar by the number of atoms of that element.
  3. Divide by the relative formula mass (mr) of the compound.
  4. Multiply by 100 to convert to a percentage.
• What is an isotope?


  Atoms with the same number of protons/electrons but with different number of neturons. An atoms mass could come up as half a neutron - 0.5 as the isotopes come in different abundances