IB Chemistry Standard Level (SL) Practice Exam

When there is an unequal distribution of charge in a molecule, a polar bond is formed. This occurs when two atoms with differing electronegativities share electrons in a covalent bond. The atom with the higher electronegativity attracts the shared electrons more strongly, resulting in a partial negative charge on that atom and a partial positive charge on the other atom. This separation of charge creates a dipole moment, characteristic of polar bonds.

In contrast, nonpolar bonds occur when electrons are shared equally between atoms, typically between two atoms of the same element or those with very similar electronegativities. Ionic bonds, on the other hand, form when there is a complete transfer of electrons from one atom to another, leading to the creation of charged ions rather than an unequal sharing of electrons. Covalent bonds generally refer to a broader category of bonding that can include both polar and nonpolar bonds, but they do not specify the unequal charge distribution that characterizes polar bonds. Therefore, the presence of an unequal distribution of charge in a molecule distinctly identifies it as having polar bonds.