Final answer:
The bond type in diatomic molecules depends on the specific molecules involved. Nonpolar covalent bonds are typical in homonuclear diatomic molecules, while polar covalent or ionic bonds may occur in heteronuclear diatomic molecules, depending on electronegativity differences.
Step-by-step explanation:
The true statement about elements that exist as diatomic molecules is that the type of bond depends on the specific molecule. In a diatomic molecule where both atoms are of the same element, the bond is typically a nonpolar covalent bond, meaning the electrons are shared equally between the atoms with no charge separation. As no difference in electronegativity exists between the identical atoms, the bond is nonpolar.
However, if the diatomic molecule consists of two different atoms, such as in hydrogen fluoride (HF), the bond can be a polar covalent bond. In this case, one atom has a higher electronegativity and therefore a greater attraction for the shared electrons, creating a partial positive charge on one end and a partial negative charge on the other, establishing a dipole moment.
Covalent bonds can either be polar or nonpolar, and the type of atoms involved often informs this. For example, bonds between two nonmetals tend to be covalent, and if there's an electronegativity difference, they are polar covalent bonds. Conversely, a very large electronegativity difference, generally between a metal and a nonmetal, would result in an ionic bond.