Answer:
atomic number
number of protons
number of electrons
Step-by-step explanation:
Fluorine is the first member of the halogen group. It has an atomic number, Z = 9 and atomic mass (A) = 19. The element is represented as: ₉F¹⁹
Atomic number (Z) = number of protons = number of electrons for a neutral atom
Atomic mass (A) = number of protons + number of electrons
Thus the number 9 represents:
-The atomic number
-number of protons
-number of electrons