Which compound has the bond with the smallest dipole moment?

Question

Quizplus · Accepted Answer

11ecba2d_11dd_1a2e_a3bf_ad192398f5a1_MD0008_00 A covalent bond is formed by shared valence electrons between two atoms (usually two nonmetals). However, differences in electronegativity can result in unequal electron sharing. In such an arrangement, a polar covalent bond results, wherein the electrons in the bond are pulled closer to the atom of greater electronegativity (giving it a partial negative charge) and away from the atom of lesser electronegativity (giving it a partial positive charge). This separation of charges across the bond results in a vector quantity called a dipole moment. Therefore, the magnitude of the dipole moment increases as the difference in electronegativity between the two atoms in the bond increases. The compounds H₂O, H₂S, H₂Se, and H₂Te each contain bonds with hydrogen. The difference among these compounds is which of the Group 16 elements (oxygen group, or chalcogens) is bonded to hydrogen. Because electronegativity tends to decrease moving down a group (column) on the periodic table, tellurium is the least electronegative of the four chalcogens. As a result, the electronegativity difference between hydrogen and tellurium in the H−Te bond is the smallest of these four hydrogen-chalcogen bonds, and therefore it has the smallest dipole moment. (Choices A, B, and C) Electronegativity increases when moving up a column on the periodic table. As a result, the electronegativity difference (and dipole moment) of the hydrogen-chalcogen bond increases moving up the column. Therefore, the ranking of the dipole moments for each of the four bonds (from largest to smallest) is as follows: H−O > H−S > H−Se > H−Te. Educational objective: The difference in electronegativity between two covalently bonded atoms is proportional to (and indicative of) the magnitude of the dipole moment along the bond between the atoms. Larger differences in electronegativity invoke larger dipole moments between atoms.

Which Compound Has the Bond with the Smallest Dipole Moment