Which statement concerning polarity is true? 1) Polarity is greatest when the difference in electronegativity of the two elements is large. 2) Polarity is greatest when both elements have high electronegativity. 3) Polarity is smallest when both elements have high electronegativity. 4) Polarity is smallest when the difference in electronegativity of the two large.
The correct answer and explanation is:
Correct Answer: 1) Polarity is greatest when the difference in electronegativity of the two elements is large.
Polarity in chemical bonds is determined by the difference in electronegativity between the two atoms involved. Electronegativity is a measure of how strongly an atom attracts shared electrons in a chemical bond. When one atom has a significantly higher electronegativity than the other, it pulls the shared electrons closer to itself. This uneven sharing creates a partial negative charge on the more electronegative atom and a partial positive charge on the less electronegative atom, resulting in a polar bond.
For example, in a bond between hydrogen and fluorine, fluorine has a much higher electronegativity than hydrogen. This large difference causes a highly polar bond. On the other hand, if two atoms have similar or equal electronegativities, the electrons are shared equally, and the bond is considered nonpolar. For example, a bond between two oxygen atoms in an O₂ molecule is nonpolar.
The greater the electronegativity difference, the more polarized the electron distribution becomes. This leads to a stronger dipole moment, which is a measure of polarity. Polar molecules tend to have higher boiling points, greater solubility in polar solvents like water, and display different chemical behavior than nonpolar ones.
Therefore, among the given options, the first statement is correct. Polarity is greatest not because both elements are highly electronegative, but because there is a significant difference between their electronegativities. When both elements have high or similar electronegativities, they may both attract electrons strongly, but if their values are close, the electron distribution remains relatively balanced and the bond stays less polar or nonpolar.