How do you find mass number of an isotope?
1 Answer
Jan 6, 2014
The mass number of an isotope is the total number of protons and neutrons in an atomic nucleus.
If you know that a nucleus has 6 protons and 6 neutrons, then its mass number is 12. If the nucleus has 6 protons and 7 neutrons, then its mass number is 13.
The symbol for an isotope lists the mass number as a superscript at the upper left. Thus, ₆¹²C represents a carbon isotope with mass number 12. ₆¹³C represents a carbon isotope with mass number 13.
