Sodium Chloride vs. Sodium Iodide

What's the Difference?

Sodium chloride and sodium iodide are both compounds that contain sodium as the cation. However, they differ in terms of the anion they contain. Sodium chloride consists of chloride ions, while sodium iodide contains iodide ions. This difference in anions leads to distinct properties and uses for these compounds. Sodium chloride is a white crystalline solid that is commonly known as table salt and is widely used as a seasoning and preservative in food. It is also used in various industrial processes such as water treatment and chemical production. On the other hand, sodium iodide is a white crystalline solid that is primarily used in medicine, particularly in the treatment of thyroid disorders. It is also used in organic synthesis and as a source of iodine in laboratory experiments.


AttributeSodium ChlorideSodium Iodide
Chemical FormulaNaClNaI
AppearanceWhite crystalline solidWhite crystalline solid
Molar Mass58.44 g/mol149.89 g/mol
Solubility in Water36 g/100 mL184 g/100 mL
Melting Point801 °C661 °C
Boiling Point1465 °C1304 °C
Crystal StructureCubicCubic
Electrical ConductivityPoor conductorPoor conductor
UsesTable salt, food seasoning, de-icing agentPhotographic film, medicine, iodized salt

Further Detail


Sodium chloride (NaCl) and sodium iodide (NaI) are both ionic compounds that contain sodium as the cation. These compounds are widely used in various industries and have important applications in everyday life. While they share some similarities, they also have distinct characteristics that set them apart. In this article, we will explore and compare the attributes of sodium chloride and sodium iodide.

Chemical Composition

Sodium chloride is composed of sodium cations (Na+) and chloride anions (Cl-). It forms a crystal lattice structure where each sodium ion is surrounded by six chloride ions, and vice versa. On the other hand, sodium iodide consists of sodium cations (Na+) and iodide anions (I-). Similar to sodium chloride, it also forms a crystal lattice structure, with each sodium ion surrounded by six iodide ions, and vice versa.


One of the key differences between sodium chloride and sodium iodide lies in their solubility in water. Sodium chloride is highly soluble in water, meaning it readily dissolves to form a clear, colorless solution. This property is due to the strong ionic bonds between sodium and chloride ions, which are easily broken by the polar nature of water molecules. On the other hand, sodium iodide is also soluble in water, but to a lesser extent compared to sodium chloride. This reduced solubility is attributed to the larger size of iodide ions, which makes it more difficult for water molecules to surround and separate them from the crystal lattice.

Physical Properties

Both sodium chloride and sodium iodide are white crystalline solids at room temperature. However, sodium chloride crystals are cubic in shape, while sodium iodide crystals are more elongated and have a hexagonal structure. In terms of density, sodium chloride has a density of 2.165 grams per cubic centimeter, whereas sodium iodide has a slightly higher density of 3.667 grams per cubic centimeter. This difference in density can be attributed to the larger size and mass of iodide ions compared to chloride ions.

Furthermore, sodium chloride has a melting point of 801 degrees Celsius and a boiling point of 1465 degrees Celsius. In contrast, sodium iodide has a lower melting point of 661 degrees Celsius and a higher boiling point of 1304 degrees Celsius. These variations in melting and boiling points can be explained by the differences in the strength of the ionic bonds between the sodium and halide ions in each compound.


Sodium chloride is perhaps most commonly known for its use as table salt, which is essential for human health and is widely used as a seasoning in food. It is also used in the production of various chemicals, such as chlorine and sodium hydroxide, which have numerous industrial applications. Additionally, sodium chloride is utilized in the medical field as a saline solution for intravenous fluids and as a disinfectant.

Sodium iodide, on the other hand, has important applications in the field of medicine and nuclear industry. It is commonly used as a supplement in iodized salt to prevent iodine deficiency disorders. Sodium iodide is also employed in diagnostic imaging, particularly in nuclear medicine, where it is used as a radioactive tracer. Furthermore, it plays a crucial role in the production of scintillation detectors, which are used to detect and measure radiation.

Health Considerations

While both sodium chloride and sodium iodide have their respective uses in the medical field, it is important to consider their potential health implications. Excessive consumption of sodium chloride, commonly found in processed foods, can contribute to high blood pressure and other cardiovascular problems. On the other hand, sodium iodide, when consumed in appropriate amounts, is essential for the proper functioning of the thyroid gland and overall thyroid health. However, excessive intake of iodine, often through supplements or iodine-rich foods, can lead to thyroid dysfunction and other health issues.


In conclusion, sodium chloride and sodium iodide are both important compounds with distinct attributes. While sodium chloride is highly soluble in water and widely used in various industries, sodium iodide has specific applications in medicine and nuclear industry. Their physical properties, such as crystal structure, density, and melting/boiling points, also differ. It is crucial to understand the characteristics and applications of these compounds to make informed decisions regarding their use and potential health implications.

Comparisons may contain inaccurate information about people, places, or facts. Please report any issues.