The melting point of sodium metal is 98°C and the melting point ofsodium chloride is 801°C.Explain the difference in the melting points of these two substances

The difference in the melting points of sodium metal and sodium chloride can be explained by the type of bonding and the structure of the two substances.

1. Sodium metal is a pure element and it has metallic bonding. Metallic bonding is the force of attraction between valence electrons and the metal ions. It is strong but not as strong as ionic bonding. The electrons in a metal lattice are delocalized and are free to move around. This means that they are not as tightly held together as ions in an ionic lattice. Therefore, less energy (in the form of heat) is required to break the bonds and melt sodium metal, resulting in a lower melting point.

2. Sodium chloride, on the other hand, is an ionic compound. It is made up of sodium ions and chloride ions. Ionic bonding is the electrostatic attraction between oppositely charged ions. These bonds are very strong. In addition, sodium chloride forms a crystalline lattice structure, which is very stable and requires a large amount of energy to break down. Therefore, sodium chloride has a much higher melting point than sodium metal.

In conclusion, the difference in the melting points of sodium metal and sodium chloride is due to the difference in the strength and nature of their bonding.