There is almost no space between the particles of solids so they cannot come closer to one another that is why solids connot be compressed.
Water is the only common substance that is naturally found as a solid, liquid or gas. Solids, liquids and gases are known as states of matter. Before we look at why things are called solids, liquids or gases, we need to know more about matter.
Matter is everything around us
Matter can be a confusing word because it has several meanings. We often hear phrases like “What is the matter?” or “It doesn’t matter”. Scientists have a different meaning for matter – matter is anything that occupies space and has mass.
Matter is made up of tiny particles. These can be atoms or groups of atoms called molecules. Atoms are like individual LEGO blocks. They are the smallest unit that anything can be broken down into without doing something extreme (like hitting a LEGO block with a hammer or smashing atoms in the Large Hadron Collider.) If atoms are like LEGO blocks, molecules are the structures you build with them. The physical characteristics of atoms and molecules decide the form or state the matter is in.
Water in its three states of matter
Water behaves differently to most other substances because, in its solid state (ice), its particles are less densely packed than in its liquid state. This is why ice floats.
Solid
Right now, you are probably sitting on a chair, using a mouse or a keyboard that is resting on a desk – all these things are solids. Something is usually described as a solid if it can hold its own shape and is hard to compress (squash). The particles in most solids are closely packed together. Even though the particles are locked into place and cannot move or slide past each other, they still vibrate a tiny bit.
Ice is water in its solid form or state. Ice keeps its shape when frozen, even if it is removed from its container. However, ice is different from most solids: its molecules are less densely packed than in liquid water. This is why ice floats.