Question

how can the tightly packed particles in ice become loosely packed by melting to water

Answer 1

Dear student!

An ice melts when we supply heat to the system. Due to the supply of this external heat the kinetic energy of molecules increases which is converted into the form of vibration between the intermolecular bonds which creates the rigidity in ice.

This vibration occurs to bear the energy within the system and so due to this vibration the bonds become loose and the force of attraction decreases which increases the distance between the molecules and the solid ice starts melting to water.