Many substances can exist in three different states of matter: as solids, liquids and gases. In each state, the substance has the same chemical make-up — the elements in its molecules have not changed, but the way in which they are connected to each other has. Scientists think of all matter as being constantly in motion. The atoms and molecules of which it is made have energy, called kinetic energy.
Solids have a set shape and volume. In a solid, the particles are more closely arranged. The particles have less net movement. Solids are rigid, meaning that the particles are “locked” into place. Solids are not easily compressible, given that they have a set volume. Solids do not flow easily, because the particles are rigidly connected and do not move past one another. In solids, the energy is not strong enough for the particles to break free of the attraction they have for each other. It is as though they are vibrating but not moving from their positions.
Liquids have a set volume, but they can change shape depending on what container they are in. The particles in a liquid move more freely within the set volume. Liquids do not form structures like solids, because of the intermolecular movement. Liquids are also not easily compressible, because of the set volume. Liquids flow easily because the particles are able to move past each other easily. The molecules in a liquid have more energy and can move away from neigh-boring molecules, so that a liquid will flow to cover as wide an area as it can.
Gases can change shape and volume. Gas particles will spread out as far as they need to in order to fill the container. They will take the shape and volume of whatever container they’re in. They are easy to compress because there is a lot of space between the particles. It also flows easily because of the amount of space between particles. The molecules of a gas have most kinetic energy. They will move apart from each other until they fill the space in which they are contained.
Picture Credit : Google