Isotopes

• Isotopes - atoms of the same element with the same number of protons (and electrons) but different number of neutrons - same atomic number, but different mass numbers.
• The relative atomic mass (Ar) - the weighed average of the masses of all of the isotopes of an element - calculated using mass number and abundance of each isotope.
• Equation:

  • Ar = (mass x % of isotope 1) + (mass x % of isotope 2) / 100