The atomic number of fluorine 19 is 9. This means that fluorine has 9 protons in its nucleus.
In the periodic table, each element is defined by its atomic number, which determines the element’s identity. For fluorine, the atomic number of 9 indicates it has 9 electrons when it is neutral, balancing the positive charge of the protons. Fluorine is a highly reactive element and is the most electronegative of all the elements, which means it has a strong tendency to attract electrons.