Here's why:

* Halogens are located in Group 17 of the periodic table. They have 7 valence electrons, making them highly electronegative and eager to gain one more electron to achieve a stable octet.

* This strong desire to gain an electron makes them very reactive, particularly with metals.

* Examples of halogens include: fluorine (F), chlorine (Cl), bromine (Br), iodine (I), and astatine (At). All of these are gases at room temperature except for bromine, which is a liquid.

Let me know if you'd like to know more about the halogens!