Melting Point
The melting point of a crystalline solid is the temperature at which it changes state from solid to liquid. When considered as the temperature of the reverse change from liquid to solid, it is referred to as the freezing point. Under standard atmospheric pressure different pure crystalline solids will each melt at a different specific temperature; thus melting point is a characteristic of a substance and can be used to identify it.

Boling Point
The boiling point of a substance is the temperature at which it can change its state from a liquid to a gas throughout the bulk of the liquid at a given pressure. A liquid may change to a gas at temperatures below the boiling point through the process of evaporation. Any change of state from a liquid to a gas at boiling point is considered vaporization.

Density
Density is a measure of mass per unit of volume. The higher an object's density, the higher its mass per volume. The average density of an object equals its total mass divided by its total volume. Density is a measure of mass per unit of volume. The higher an object's density, the higher its mass per volume. The average density of an object equals its total mass divided by its total volume.