Final answer:
A normal fluorine atom (19F) contains 9 protons, 10 neutrons, and 9 electrons, as determined by its atomic number (9) and mass number (19).
Step-by-step explanation:
The element fluorine, represented by the symbol 19F, has an atomic number of 9. This tells us that a neutral fluorine atom has 9 protons. Since the number of electrons in a neutral atom is equal to the number of protons, fluorine also has 9 electrons. The mass number of fluorine is 19, which is the sum of protons and neutrons in the atom's nucleus. To find the number of neutrons, we subtract the atomic number from the mass number: 19 (mass number) - 9 (atomic number) = 10 neutrons.
Therefore, a normal fluorine atom (19F) contains 9 protons, 10 neutrons, and 9 electrons.