What is the mass number of a fluorine atom with 8 neutrons?

The atomic number is nine, because there are 9 protons. The mass number is 19, because an element does not have a charge, unless it forms to an ion. Therefore, if protons and neutrons have an amu of 1, the equation is as follows: Mass number (19)- Atomic number (9)= 10. There are 10 Neutrons and 9 protons.