A molecule that is composed of only one kind of atom is called a diatomic element.

Here are some examples:

* Hydrogen (H2)

* Oxygen (O2)

* Nitrogen (N2)

* Fluorine (F2)

* Chlorine (Cl2)

* Bromine (Br2)

* Iodine (I2)

These elements exist as diatomic molecules because they are more stable in this form than as single atoms.