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Sodium fluoride is an inorganic ionic compound, dissolving in water to give separated Na + and F − ions. Like sodium chloride , it crystallizes in a cubic motif where both Na + and F − occupy octahedral coordination sites ; [ 33 ] [ 34 ] its lattice spacing, approximately 462 pm , is smaller than that of sodium chloride (564 pm).
With other atoms, fluorine forms either polar covalent bonds or ionic bonds. Most frequently, covalent bonds involving fluorine atoms are single bonds, although at least two examples of a higher order bond exist. [2] Fluoride may act as a bridging ligand between two metals in some complex molecules.
Bonds with partially ionic and partially covalent characters are called polar covalent bonds. [2] Ionic compounds conduct electricity when molten or in solution, typically not when solid. Ionic compounds generally have a high melting point, depending on the charge of the ions they consist of. The higher the charges the stronger the cohesive ...
The circumstances under which a compound will have ionic or covalent character can typically be understood using Fajans' rules, which use only charges and the sizes of each ion. According to these rules, compounds with the most ionic character will have large positive ions with a low charge, bonded to a small negative ion with a high charge. [25]
This is because the greater covalent character of the bonds in AgCl and AgBr reduces the bond length and hence the apparent ionic radius of Ag +, an effect which is not present in the halides of the more electropositive sodium, nor in silver fluoride in which the fluoride ion is relatively unpolarizable.
Fluoride is sold in tablets for cavity prevention. Fluoride-containing compounds, such as sodium fluoride or sodium monofluorophosphate are used in topical and systemic fluoride therapy for preventing tooth decay. They are used for water fluoridation and in many products associated with oral hygiene. [31]
Ionic interactions involve the attraction of ions or molecules with full permanent charges of opposite signs. For example, sodium fluoride involves the attraction of the positive charge on sodium (Na +) with the negative charge on fluoride (F −). [9]
Thus sodium chloride (with a low positive charge (+1), a fairly large cation (~1 Å) and relatively small anion (0.2 Å) is ionic; but aluminium iodide (AlI 3) (with a high positive charge (+3) and a large anion) is covalent. Polarization will be increased by: High charge and small size of the cation, due to ionic potential Å Z+/r+ ...