Editing Halogen (section)

==== Molecules ====

===== Diatomic halogen molecules =====

The stable halogens form [[homonuclear]] [[diatomic]] [[molecules]].
Due to relatively weak intermolecular forces, chlorine and fluorine form part of the group known as "elemental gases".

{| class="wikitable" style="margin: 1em auto 1em auto; text-align:center;"
|-
! halogen || molecule || structure || model || ''d''(X−X) / pm<br />(gas phase) || ''d''(X−X) / pm<br />(solid phase)
|-
| [[fluorine]] || F<sub>2</sub> || [[Image:Difluorine-2D-dimensions.png|45px]] || [[Image:Fluorine-3D-vdW.png|45px]] || 143 || 149
|-
| [[chlorine]] || Cl<sub>2</sub> || [[Image:Dichlorine-2D-dimensions.png|70px]] || [[Image:Chlorine-3D-vdW.png|63px]] || 199 || 198
|-
| [[bromine]] || Br<sub>2</sub> || [[Image:Dibromine-2D-dimensions.png|80px]] || [[Image:Bromine-3D-vdW.png|72px]] || 228 || 227
|-
| [[iodine]] || I<sub>2</sub> || [[Image:Diiodine-2D-dimensions.png|70px]] || [[Image:Iodine-3D-vdW.png|84px]] || 266 || 272
<!--don't add astatine; it's not proven to form At2 molecules-->
|}

The elements become less reactive and have higher melting points as the atomic number increases. The higher melting points are caused by stronger [[London dispersion force]]s resulting from more electrons.