describe the difference in terms of arrangement of molecule, volume & density of each phases of matter.?

Answer 1

Water would be a good example of a molecule that exhibits all the phases of matter. In it's most energetic phase, it is hot enough to strip one or more electons from the field orbiting the H20 cluster and its atoms and is ionized. Ionized molecules (and dissociated atoms) bounce off each other but do not combine and thus act like a very hot gas. Energy is held in the velocity of the of the molecules and the average velocity accounts for the temperature of the whole. Ionized gas can expand to fill its container but may be cooled by contact with any walls. It is often held suspended within magnetic fields (bottles) and is the least dense form of matter.

If the water is cooled to steam, there is very little ionization but the molecules still bounce off each other like speeding bullets and exert pressure on each other and the walls of any container which will be completely filled. Oddly there can be specks of ice in the steam due to a tiny collection of water molucles that have momentarily lost all their energy in collisions, but that only last until another collision adds back the lost energy. Again, the energy of the molecules depends on their velocity and their average velocity accounts for their pressure and temperature. The lid of any container is being bombarded by millions of collisions per second and that adds up to the pressure trying to blow the lid off. That same kind of pressure is used to operate the pistons of a steam engine.

If the steam is cooled it will condense into hot water which can be further cooled to just above the freezing point by removing heat energy. If the container is air cooled, the molecules in the container wall lose energy to the air and the hot water molecules lose energy to the cooler container wall by direct conduction. The water, now a liquid, is contained within an ocean of infrared photons and more are lost to the container than gained. The water molecules repel each other like a gymn full of basketballs and gravity holds them to the lower portion of the container which they partially fill. Warmer molecules are slightly larger and more buoyant and can circulate within a current to the top of the container. As the water cools it slightly contracts (like shrinking basketballs) because the electrons orbiting the molecules and atoms of the H2O are circling in lower less energetic orbits. Water is of course much more dense than ionized water or steam. Oddly there can be specs of ice or steam within the water depending on the instantaneous energy of small clusters of molecules that quickly return to the average temperature. Water can form temporarily attracted collections of molecules but nothing is permanent.

When water is cooled to below the freezing point it becomes a solid. The water forms irregular chains of molecules like a room full of small bent and curved wires or pieces of chain. The chains use up the space less efficiently than free water molecules and water expands slightly while freezing. That is why one tenth of an iceberg sticks up out of the water. The ice is therefore less dense than liquid water. If the ice is cooled below the freezing point it contracts just like any other material such as steel. Oddly again speck of water and steam can exist instantly within the ice due to temporary energy levels of a small collection of molecules. The average temperature of the ice depends on the average energy of all the ice molecules as they vibrate within their crystaline structures. As the ice is further cooled toward absolute zero, the vibrations of the molecules become weaker and weaker but it is near impossible to reach absolute zero except perhaps for an instantaneous cluster of molecules soon to be vibrated again by its frigid neighbors. Hope that helps a little.

Answer 2

A simple explanation:
Solid: long-range order, low volume, high density.
Liquid: little long-range order, atomic spacing about same as solid so volume and density also similar to solid.
Gas: no long-range order (random distribution), spacing is greater than 5 atomic diameters so volume is much higher and density much lower than other states.