Final answer:
When two identical atoms form a covalent bond, it is a nonpolar covalent bond due to the equal sharing of electrons resulting from identical electronegativities. This type of bond is seen in diatomic molecules such as O₂ and H₂, distinguishing it from polar covalent and other types of covalent bonds.
Step-by-step explanation:
If two covalently bonded atoms are identical, the bond is a nonpolar covalent bond. This occurs because atoms of the same element have the same electronegativity, and thus, they share the bonding electron pair equally. For example, the diatomic molecule oxygen (O₂) forms a nonpolar covalent bond as both oxygen atoms attract the shared electrons with the same force, leading to an equal distribution.
Pure covalent bonds, also known as nonpolar covalent bonds, are characteristic of molecules where the bonded atoms have identical electronegativities. No atom attracts the bonding pair more than the other. Hence, such a bond cannot be polar or ionic.
Contrary to this, a polar covalent bond forms between atoms that have different electronegativities, leading to an unequal sharing of electron pairs and a resulting dipole. Thus, for two identical atoms, the covalent bond formed is nonpolar, not polar covalent, dipole covalent, or coordinate covalent.