Isotopes & relative atomic mass

• Isotopes are different forms of the same element that have the same number of protons but different number of neutrons
• Because isotopes have different number of neutrons different isotopes will have different masses
• Relative atomic mass is the calculation of the average mass of all the isotopes that make up an element
• Isotope abundance is how common or rare the isotope is
• Relative atomic mass equation

  Sum of ( isotope abundance x isotope mass) / sum of abundance of all isotopes

  
• Relative atomic mass symbol is Ar
• • The symbol for an isotope is the chemical symbol (or word) followed by a dash and then the mass number
  • So, C-14 is the isotope of carbon which contains 6 protons and 6 electrons, but the 14 signifies that it has 8 neutrons (14 - 6 = 8)
  • 6 is the number of protons
  • It can also be written as 14C
• • Isotopes display the same chemical characteristics
  • This is because they have the same number of electrons in their outer shells, and this is what determines their chemistry
• isotopes hydrogen

  Structure of isotopes hydrogen