Diatomic Elements — Importance & Examples

We know that chemistry is all about stability. Atoms and molecules want to be in the lowest energy state. Almost all the elements on the periodic table are stable as individual atoms. However, there are seven elements called diatomic elements. Diatomic means that the molecule contains two atoms. The diatomic elements are Hydrogen (H), Nitrogen (N), Oxygen (O), fluorine (F), Chlorine (Cl), Bromine (Br), and Iodine (I). In nature, the diatomic elements only exist as $H_{2}$, $N_{2}$, $O_{2}$, $F_{2}$, $Cl_{2}$, $Br_{2}$, and $I_{2}$.

Why do the Diatomic Elements from?

The diatomic elements have high electronegativities. They are more stable when they bond with themselves. You will notice that five of the seven (hydrogen and the halogens) are only one electron away from a full octet. By covalent bonding with themselves, they complete their octets. The same is true of nitrogen and oxygen. However, nitrogen can share three of its valance electrons, so it will triple bond with itself. Oxygen can share two of its valance electrons so it will double bond with itself.

Physical Properties of the Diatomic Elements

Five of the seven diatomic elements are gasses at room temperature. The two exceptions are Bromine and Iodine. Bromine is a liquid and Iodine is solid. Remember, intermolecular forces cause the physical properties of covalently bonded molecules. The diatomic elements only experience Van der Waal's forces. Bromine and Iodine, have enough electrons to create strong temporary dipoles. Temporary dipoles are caused by the London Dispersion Effect.

Chemical Properties of the Diatomic Elements

A variety of different reactions use diatomic elements. Remember that as we move down the periodic table, bond length increases. Because $Br_{2}$ and $I_{2}$ have large bond lengths, they have lower bond energy. So, $Br_{2}$ and $I_{2}$ are more reactive than the other diatomic elements. Overall, a few reactions are energetically favorable and happen spontaneously. However, the diatomic elements are very stable so often chemists use a catalyst to lower the activation energy.

Diatomic Elements: What are diatomic elements?

Diatomic elements are elements that prefer to bond with themselves.

What are the Diatomic Elements?

by Tyler DeWitt

In this video, Dr. Dewitt answers what diatomic elements are and demonstrates their Lewis structures.

All the diatomic elements pair up, forming a molecule. You cannot find a single atom of these elements.

You can memorize the seven diatomic elements by remembering: “ Have no fear of ice cold beer.” The first letter of each word in the phrase corresponds to the seven elements: Hydrogen, nitrogen, fluorine, oxygen, iodine, chlorine, and bromine.

None of the diatomic elements by themselves has a full valence shell. However, when two diatomic elements come together, they share electrons which allows both atoms have a full valence shell.