When ice melts, the heat energy gained from surroundings is used to weaken the bonds between particles. The movement of the particles changes from vibrating in fixed positions in the solid state to moving and sliding over one another freely in confined spaces in the liquid state. The arrangement of the particles changes from regularly arranged, tightly packed together in the solid state to irregularly arranged, close together in the liquid state.

The average kinetic energy of the particles remains constant, so temperature remains constant during melting.