Iodine and bromine are both non-metals in the same group (group 7) of the periodic table. When iodine and bromine react, they form a diatomic molecule, IBr, in which the iodine and bromine atoms are held together by a covalent bond.

A covalent bond is a type of chemical bond where two atoms share electron pairs to form a stable electron configuration. In the case of IBr, the iodine and bromine atoms each contribute one electron to the bond, forming a single covalent bond.

Covalent bonding is more common between non-metals than between metals and non-metals because non-metals have a lower electronegativity and are more willing to share electrons. In addition, the electronegativity difference between iodine and bromine is small, which also favors the formation of a covalent bond.