Based on the information above, do you think that fluorine has common isotopes? justify your answer.

Answer is: fluorine does not have common isotopes, because its average atomic mass is 19.

Fluorine has only one isotope occurs naturally in abundance, the stable isotope F-19.

This isotope has:

1) n(p⁺) = 9; fluorine has atomic number Z = 9 (total number of protons).

2) n(e⁻) = 9; in an element, number of electrons and protons are the same.

3) n(n°) = 10; mass number of this isotope is A = 19. Mass nummber is total number of protons and neutrons in a nucleus, so number of neutrons is:  

n(n°) = A-Z.

n(n°) = 19-9.

n(n°) =10.