The halogen group is the 7th column in the periodic table, which means halogens need a single electron more for their valence shell. This means that all halogens are highly reactive, like the elements ofGroup I: Alkali metals​. Halogens can even react with their containers, like F, fluorine (fluori)​ does with glass bottles.

• nonmetals
• feature solids, liquids and gases
• highly reactive
  • form ions of charge 1−
• highly toxic, yet used as sanitizers
  • Cl, chlorine (kloori)​ in pools
  • Povidone-iodine​ in hospitals
• diatomic as gases