12.
Explanation
The percent ionic character in a molecule is influenced by the dipole moment and the electronegativity difference between the atoms involved. The percent ionic character can be estimated using the Pauling scale, which relates the observed dipole moment to the maximum possible dipole moment for a purely ionic bond.
Here's how these factors affect the percent ionic character in a molecule:
1. Dipole Moment (μ):
- The dipole moment is a measure of the polarity of a molecule. It arises due to the separation of positive and negative charges within the molecule.
- A larger dipole moment indicates a more polar bond or molecule, while a smaller dipole moment suggests a less polar or nonpolar bond.
- In the context of estimating ionic character, a larger dipole moment implies a higher degree of ionic character.
2. Electronegativity Difference (ΔEN):
- The electronegativity difference between two atoms in a bond or molecule reflects their relative abilities to attract electrons. The greater the difference, the more polar the bond or molecule becomes.
- A larger electronegativity difference implies a more polar bond or molecule, while a smaller difference suggests a less polar bond.
- For molecules with covalent bonds, a larger electronegativity difference indicates a higher percent ionic character.
3. Percent Ionic Character Estimation
- If the actual dipole moment (μ) is close to or approaching the maximum possible dipole moment (μ_max), the molecule has a high percent ionic character, indicating a more ionic nature.
In summary, both the dipole moment and the electronegativity difference contribute to the percent ionic character of a molecule. A larger dipole moment and a greater electronegativity difference result in a higher percent ionic character, indicating a stronger ionic character or polar nature of the molecule. This concept helps us understand the extent of ionic and covalent character in chemical bonds and molecules.