What Are the 7 Diatomic Elements?

Diatomic Elements on the Periodic Table

This is iodine, an example of a diatomic element. The halogens are elements that form diatomic molecules.
This is iodine, an example of a diatomic element. The halogens are elements that form diatomic molecules. Lester V. Bergman / Getty Images

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. There are seven 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