Here's why:
* Valence Electrons: These are the electrons in the outermost shell of an atom, and they're the ones involved in chemical bonding.
* Periodic Table Organization: The periodic table is organized based on the number of valence electrons an element has. Elements within the same group (vertical column) have the same number of valence electrons.
* Group 7 (Halogens): All elements in Group 7 have 7 valence electrons. This makes them highly reactive as they tend to gain one electron to achieve a stable octet (8 electrons) in their outermost shell.
In summary: Fluorine has 7 valence electrons, which is the defining characteristic of elements in Group 7 of the periodic table, also known as the halogens.
