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Which elements commonly form homonuclear diatomic molecules?

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representations of molecular structure — molecule Several methods of representing a molecule's structure. In Lewis structures, element symbols represent atoms, and dots represent electrons surrounding them. A pair of shared electrons (covalent bond) may also be shown as a single dash. The ball-and-stick model better illustrates the spatial arrangement of the atoms. For aromatic compounds, the Kekulé structure is common, in which each bond is represented by a dash, carbon atoms are implied where two or more lines meet, and hydrogen atoms are usually omitted. Bond-line formulas, similar to the Kekulé structure, are often used for complex nonaromatic organic compounds. Sugars are often drawn as Fischer projections, in which the carbon “backbone” is drawn as a straight vertical line, with carbon atoms implied where horizontal lines intersect the vertical one.

Homonuclear diatomic molecules consist of two atoms of the same chemical element bonded together. Several elements commonly exist in this form, particularly as gases under standard conditions. These include:

Hydrogen ( $H_{2}$ )
Nitrogen ( $N_{2}$ )
Oxygen ( $O_{2}$ )
Fluorine ( $F_{2}$ )
Chlorine ( $C l_{2}$ )
Bromine ( $B r_{2}$ )
Iodine ( $I_{2}$ )

Additionally, other elements can form homonuclear diatomic molecules under specific or extreme conditions, such as lithium ( $L i_{2}$ ), carbon ( $C_{2}$ ), and helium ( $H e_{2}$ ). For instance, helium dimers are formed only at extremely low temperatures through van der Waals forces.12