The [?] are a family of gases that are found in Group [?] of the periodic table. This is to the right of the table, which means that all the halogens are [?]. When they are gases, the molecules have atoms.

All the halogens have seven outer shell [?], which means that they only need to gain electron to get a [?] gas structure. Gaining one electron is much easier than losing seven electrons. So the halogens form [?] ions when they react with metals.

If they react with other non-metals, they form [?] bonds. Chlorine reacts with hydrogen to make hydrogen gas. The bond is covalent. Hydrogen chloride reacts with water to form acid. Then the hydrogen and chlorine dissociate into [?] rather than staying as molecules. Because most of the molecules dissociate, hydrochloric acid is a acid with a [?] of 1.

[?] is the most reactive of the gases; is the least reactive. So the trend down the group is for the elements to be reactive.

Chlorine will [?] iodine and from their compounds. Fluorine will displace all the other halogens from their .