A diatomic element is a molecule of an element consisting of two atoms. It is a form of homonuclear diatomic molcule. There are only 7 diatomic elements in total and only 5 diatomic elements at standard temperature and pressure (STP).
The following 5 element gases are found as diatomic molecules at room temperature and pressure:
- Hydrogen – H2
- Nitrogen – N2
- Oxygen – O2
- Fluorine – F2
- Chlorine – Cl2
Bromine and iodine commonly exist in liquid form, but also as diatomic gases at slightly higher temperatures, making a total of 7 diatomic elements.
- Bromine – Br2
- Iodine – I2
How To Remember the Diatomic Elements
An easy mnemonic device is:
Have No Fear Of Ice Cold Beer
The diatomic elements are the –ine halogens (fluorine, chlorine, bromine, iodine) and elements with a –gen ending (hydrogen, oxygen, nitrogen). Astatine is another halogen, but its behavior is not known.