An Allegory is used to tell a story that has characters, a setting, as well as other types of symbols, that have both literal and figurative meanings.
Chlorine is counted among this group along with hydrogen (H 2), iodine (I 2), bromine (Br 2), oxygen (O 2), nitrogen (N 2) and fluorine (Fl 2). With seven electrons in its outermost orbit--one electron short of a stable eight-- the element chlorine exists in nature as a diatomic molecule. This arrangement allows two chlorine atoms to share their outermost orbit electrons, achieving stability, compared to the single atom.
Valence electrons by definition are the number of electrons in the valence shell. The atomic number of Chlorine is 17. Hence the configuration of electrons would be 2,8,7. Hence the number of valence electrons in Chlorine is 7. However if you talk about valency that would be number of electrons an atom has to gain/loose to achieve the stable state.