Understanding Isotopes: Same Protons, Different Neutrons

  Isotopes. Isotopes are the same except extra neusons. They have the same number of protons but different number of neutrons. Same atomic number, * different mass number Carbon 12 Carbon 13 12 13 C. C6 6 6 protons 6 procons 6 electrons 6 electrons 6 nevtrons 7 neutrons Relative Sum of (isotope abundance x isotope mass no.) Atomic = Mass Sum of abundances of all the isotopes (Ar) Example CU-63- - abundance of 69.2% CU-65- - abundance of 30.8% (69.2x63) +(30.8x65) = 6361.6 =63.616 69.2 + 30.8 100 =63.6