The group of elements that has seven valence electrons are the halogens.

Here's why:

* Valence electrons: These are the electrons in the outermost energy level of an atom, which are involved in chemical bonding.

* Halogens: This group is found in Group 17 (VIIA) of the periodic table. They include fluorine (F), chlorine (Cl), bromine (Br), iodine (I), and astatine (At).

Having seven valence electrons makes halogens highly reactive. They tend to gain one electron to achieve a stable octet (eight valence electrons) and form negative ions with a charge of -1.