The halogens are five non-metallic elements found in group 17 of the periodic table. The term "halogen" means "salt-former" and compounds containing halogens are called "salts". All halogens have 7 electrons in their outer shells, giving them an oxidation number of -1. The halogens exist, at room temperature, in all three states of matter:

• Solid- Iodine, Astatine
• Liquid- Bromine
• Gas- Fluorine, Chlorine

• Fluorine
• Chlorine
• Bromine
• Iodine
• Astatine