How many valence electrons do the halogens possess?

The halogens posses seven valence electrons

Explanation:

Valence electrons are the electrons in the outermost orbitals of the atoms, which are the orbitals with the highest main energy level (principal quantum number).

Halogens are the elements of the group 17 of the periodic table: F, Cl, Br, I, At.

You can tell the number of valence electrons of the representative elements from the number of the group to which they belong. For the representative elements, the number of valence electrons equal the unit digit of the group number.

This table summarizes it:

Group number number of valence electrons

1 1

2 2

13 3

14 4

15 5

16 6

17 7

18 8

So, in conclusion, the halogens possess 7 valence electrons.