Chapter 4: Problem 23
Among \(\mathrm{NaP}, \mathrm{NaCl}, \mathrm{NaBr}\) and \(\mathrm{Nal}\), the \(\mathrm{NaF}\) has highest melting point because (1) It has maximum ionic character. (2) It has minimum ionic character. (3) It has associated molecules. (4) It has least molecular weight.
Short Answer
Step by step solution
Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Ionic Character
Fluorine is the most electronegative element and forms very strong ionic bonds with sodium. This makes NaF the compound with the highest ionic character among the sodium halides. As a result, the bonds in NaF are very strong, leading to a high melting point.
When comparing ionic character, it's important to look at both the size of the ions and their charges. Generally, smaller ions with higher charges will have stronger attractions and thus higher ionic character.
Melting Point
In the case of sodium halides, NaF has the highest melting point because of its strong ionic bonds. The small size of the fluoride ion and the high electronegativity of fluorine contribute to these strong bonds. Thus, more energy (higher temperature) is needed to break these bonds and melt the compound.
This concept emphasizes the linkage between ionic character and melting point: the greater the ionic character, the higher the melting point.
Ionic Bonding Strength
In sodium halides, the strength of the ionic bond decreases as we move from fluorine to iodine in the halide group. NaF has the strongest ionic bond because fluoride ions are small and highly electronegative. This results in a high degree of electrostatic attraction between the sodium and fluoride ions.
The stronger the ionic bonding in a compound, the higher the energy required to break these bonds during melting. This explains why NaF, with its strong ionic bonds, has a much higher melting point than NaCl, NaBr, and NaI. Ionic bonding strength is therefore a critical factor in understanding the melting points of various sodium halides.