The seven elements that form diatomic molecules when not part of a compound are:

* Hydrogen (H): H₂

* Nitrogen (N): N₂

* Oxygen (O): O₂

* Fluorine (F): F₂

* Chlorine (Cl): Cl₂

* Bromine (Br): Br₂

* Iodine (I): I₂

These elements are known as diatomic elements because they exist naturally as molecules containing two atoms of the same element bonded together.