Question

when heat is being supplied to a solid what does the heat energy do the particles of solid

Answer 1

it loosens the particles of the object and changes it's State after a certain point of time.

Answer 2

The heat energy supplied to the solid increases the kinetic energy of the molecules, as a result they start vibrating and transfer the energy to adjacent molecules and this goes on. If the heat supplied is sufficient it may change state of substance from solid to liquid or gas.