Fluorine is an element that belongs to the halogen group in the periodic table. It has an atomic number of 9, and its electron configuration is 1s^2 2s^2 2p^5. Fluorine is highly electronegative, meaning it has a strong tendency to attract electrons towards itself when it forms chemical bonds. This property is due to its relatively small atomic size and high effective nuclear charge.

Fluorine has a total of 7 valence electrons, which are electrons in its outermost energy level (2s^2 2p^5). In order to achieve a stable electron configuration, fluorine tends to gain one electron to complete its octet. By gaining one electron, fluorine achieves a stable electron configuration similar to the nearest noble gas, neon (1s^2 2s^2 2p^6).

Fluorine's strong electronegativity and its tendency to gain electrons result in it having only one common oxidation state, which is -1. In this oxidation state, fluorine gains one electron to achieve a stable configuration of 1s^2 2s^2 2p^6. This oxidation state is commonly observed in compounds where fluorine acts as an anion, such as in the compound sodium fluoride (NaF). In NaF, fluorine gains an electron from sodium to form the F- ion.

It is important to note that although fluorine is highly electronegative and tends to gain electrons, it does not have the capability to lose electrons easily and form positive oxidation states. This is because fluorine's valence shell is almost full, and losing electrons would require a significant amount of energy.

In conclusion, fluorine has only one common oxidation state, which is -1. This is due to its strong electronegativity and its tendency to gain one electron to achieve a stable electron configuration.