What Are the 7 Diatomic Elements?

Diatomic Elements on the Periodic Table

An illustration of the mnemonic device 'have no fear of ice cold beer' used to memorize the diatomic elements

ThoughtCo.

Diatomic molecules consist of two atoms bonded together. In contrast, monatomic elements consist of single atoms (e.g., Ar, He). Many compounds are diatomic, such as HCl, NaCl, and KBr. Diatomic compounds consist of two different elements. There are seven pure elements that form diatomic molecules.

This is a list of the seven diatomic elements. The seven diatomic elements are:

  • Hydrogen (H2)
  • Nitrogen (N2)
  • Oxygen (O2)
  • Fluorine (F2)
  • Chlorine (Cl2)
  • Iodine (I2)
  • Bromine (Br2)

All of these elements are nonmetals, since the halogens are a special type of nonmetallic element. Bromine is a liquid at room temperature, while the other elements all gases under ordinary conditions. As the temperature is lowered or pressure is increased, the other elements become diatomic liquids.

Astatine (atomic number 85, symbol At) and tennessine (atomic number 117, symbol Ts) are also in the halogen group and may form diatomic molecules. However, some scientists predict tennessine may behave more like a noble gas.

How To Remember the Diatomic Elements

The elements ending with "-gen" including halogens form diatomic molecules. An easy-to-remember mnemonic for the diatomic elements is: Have No Fear Of Ice Cold Beer

Key Points

  • Diatomic elements are pure elements that form molecules consisting of two atoms bonded together.
  • There are seven diatomic elements: hydrogen, nitrogen, oxygen, fluorine, chlorine, iodine, bromine.
  • These elements can exist in pure form in other arrangements. For example, oxygen can exist as the triatomic molecule, ozone.