Here are some examples:

* H₂ (Hydrogen)

* O₂ (Oxygen)

* N₂ (Nitrogen)

* Cl₂ (Chlorine)

* Br₂ (Bromine)

* I₂ (Iodine)

* F₂ (Fluorine)

* CO (Carbon Monoxide)

* NO (Nitric Oxide)

There are also diatomic molecules made up of two different atoms (like CO and NO).