Here's why:

* Thermal conductivity is the ability of a material to transfer heat energy.

* Materials with strong bonds (like the ionic bonds in sodium chloride) tend to be good thermal conductors. This is because the atoms within the material are able to vibrate and transfer energy efficiently.

However, the thermal conductivity of sodium chloride is relatively low compared to metals like copper or aluminum. This is because the ionic bonds are not as strong as the metallic bonds in those materials.

Here's a comparison:

* Copper: 401 W/mK

* Aluminum: 237 W/mK

* Sodium chloride: 5.9 W/mK

Therefore, while sodium chloride does have thermal conductivity, it is not a particularly good conductor of heat.