Why does sugar melt faster than salt?

Sugar is a molecule held together by covalent bonds (the electrons between the atoms that make up sugar are shared throughout the molecule). Salt is held together by ionic bonds (electrons are transferred from one atom to another to produce ions; a positive ion and a negative ion). These ions are basically like tiny magnets so they all stick to each other and are very hard to pull apart. Think about it, have you ever tried to separate strong magnets that were stuck together? It is not easy!

Now, the sugar (covalently bonded molecules) contain no ions; they do NOT act like little magnets so they are really easy to pull apart.

Now, when something melts, you are basically giving the molecules more energy so they can move around more and act like a liquid. Since the sugar molecules are not attracted to each other, it takes a lot less energy to pull them apart (melt them) so they melt at a lower temperature. The salt molecules, because they act like tiny magnets, are highly attracted to each other so it takes a lot of energy to separate them so they melt at a much higher temperature.

Sugar Melt Ice

In order for sugar to melt, you need to break the intermolecular forces that hold the sugar molecules together. However, when it does melt, only the intermolecular forces break, not the covalent bonds that are holding the atoms in the molecule together.

For salt to melt, you need to break the ionic bonds that hold the sodium ions and chloride ions together.

Ionic bonds are much stronger than the intermolecular forces (Hydrogen-bonds in this case). Therefore you need to put more energy (in the form of heat) in to salt to cause it to melt than you would need to put in to sugar.

I do physics, i believe the density, mass and/or volume in sugar is lower so it melts down much faster. :p

Basically, sugar is covalent while Nacl is ionic.. ionic bond is stronger than covalent.