Difference Between Sodium Fluoride and Fluoride

Main Difference – Sodium Fluoride vs Fluoride

Sodium fluoride is a chemical compound. Fluoride is an anion. These two chemical species are very important in different applications. For example, sodium fluoride is used as a medication. When considering the chemical structure of sodium fluoride, it is composed of sodium cations and fluoride anions. Therefore, sodium fluoride is a good source of fluoride anions. Sometimes, the term fluoride is used to describe any compound that is composed of a metal cation and fluoride anion. In other words, metal fluorides are known as fluorides in general use. However, the term fluoride is actually used for the anion. The main difference between sodium fluoride and fluoride is that sodium fluoride is a neutral compound whereas fluoride is an anion.

Key Areas Covered

1. What is Sodium Fluoride
      – Definition, Properties, and Reactions
2. What is Fluoride
      – Definition, Properties, and Reactions
3. What is the Difference Between Sodium Fluoride and Fluoride
      – Comparison of Key Differences

Key Terms: Anion, Fluoride, Sodium Fluoride (NaF)

What is Sodium Fluoride

Sodium fluoride is an ionic compound composed of Na⁺ ions and F^– ions. The chemical formula of sodium fluoride is given as NaF. The molar mass of sodium fluoride is about 42 g/mol. It appears as a greenish white solid at room temperature. Sodium fluoride is an odorless compound. Since it is an ionic compound, the melting point and boiling point are very high. The melting point of sodium fluoride is 993⁰C. The boiling point is about 1700⁰C. When the solid sodium fluoride is heated, it forms a toxic gas: hydrogen fluoride (HF).

Sodium fluoride is naturally found in a rare mineral called Villiaumite in small quantities. Therefore, the industrial production is the major source of the sodium fluoride. It is commonly prepared by the reaction between hydrofluoric acid and a base such as sodium hydroxide.

HF  +   NaOH   →    NaF     +   H₂O

Sodium fluoride is soluble in water. When it is dissolved in water, it gives aqueous sodium ions and fluoride ions. Therefore, the aqueous solutions of sodium fluoride can conduct electricity. The ions in the solution cause the conductivity of the solution. Since sodium fluoride is a sodium salt, it has a salty taste.

Figure 1: NaF is an Ionic Compound

Sodium fluoride is a medication used to prevent cavities in teeth. It makes teeth stronger and resistant to decay from bacterial activities. Therefore, toothpaste is often composed of sodium fluorides. However, excessive amounts of sodium fluoride cause the teeth to become yellowish. In addition, sodium fluoride is a good cleaning agent.

What is Fluoride

Fluoride is an inorganic anion. It is formed from the element fluorine. The chemical symbol for fluoride is F^–. The molar mass is about 19 g/mol. Fluorine atoms are composed of 7 electrons in their outermost orbitals. Therefore, they lack one electron in order to get a stable electronic configuration (if there are 8 electrons in the outermost orbital of an atom, it is very stable). When one electron is obtained from outside, there aren’t enough positive charges in the nucleus to neutralize the incoming electron. Hence, it forms an anion having -1 electrical charge. This anion is the fluoride ion.

Figure 2: Fluorine atom needs one more electron to fill its outermost orbital.

Fluoride ions can be found as a component in some minerals. For example, fluorite is composed of CaF₂ units. There fluoride ions are in combination with calcium ions.

Fluoride ions sometimes react as a base. Then it can combine with H⁺ by giving electrons to hydrogen atoms. Reaction between water and fluoride ions produces hydrogen fluoride (HF). This is a reversible reaction.

As fluoride ions are good for teeth, water plants add some amount of fluoride ions to the water.

Difference Between Sodium Fluoride and Fluoride

Definition

Sodium Fluoride: Sodium fluoride is an ionic compound composed of Na⁺ ions and F^– ions.

Fluoride: Fluoride is an inorganic anion.

Electrical Charge

Sodium Fluoride: Sodium fluoride is a neutral compound.

Fluoride: Fluoride ions are negatively charged compounds.

Molar Mass

Sodium Fluoride: The molar mass of sodium fluoride is about 42 g/mol.

Fluoride: The molar mass of fluoride is about 19 g/mol.

Basic Units

Sodium Fluoride: One unit of sodium fluoride compound is composed of a Na⁺ ion and F^– ion.

Fluoride: One unit of fluoride is composed of F^– ion.

Conclusion

Fluorides are very important components in our daily food since fluoride ions are a good medication for healthy teeth. As the amount of fluoride present in the food that we consume daily is minute, fluoride ions added to water. Thus, drinking water is composed of fluoride ions. Sodium fluoride is used in toothpaste production. The main difference between sodium fluoride and fluoride is that sodium fluoride is a neutral compound whereas fluoride is an anion.

References:

1. “Fluoride.” Wikipedia, Wikimedia Foundation, 19 Aug. 2017, Available here. Accessed 29 Aug. 2017.
2. “Sodium fluoride Formula – Sodium Fluoride Uses, Properties, Structure and Formula.” Math, Available here. Accessed 29 Aug. 2017.

Image Courtesy:

1. “Sodium-fluoride-3D-ionic” By Benjah-bmm27 – Own work (Public Domain) via Commons Wikimedia
2. “Electron shell 009 Fluorine – no label” By Pumbaa (original work by Greg Robson) – File:Electron shell 009 Fluorine.svg (CC BY-SA 2.0 uk) via Commons Wikimedia