How are elements classified in the periodic table?
In order of increasing proton number.
As you move left to right on the periodic table there is one proton that is added to the nucleus element.
This should tell you that the identity of an element is based on the number of protons. If you were thinking that, you're exactly right.
They are also in order of electron affinity, or the ability to take an electron. This trend is up and to the right, so Florine is the most electronegative, or has the highest electron affinity.