So how do we know about Matter and microscopic particles anyways?
Microscopes & Cameras
Scientists have developed instruments that can create discrete images of atoms and molecules that show that the atoms and molecules often occur in well-ordered arrays.
Moving Molecules
When scientists take pictures of these atoms and molecules they have to capture them when the objects when they are in the solid state or when they are frozen. This way, at a lower temperature, the tiny particles that make up the object will be motionless. They cannot capture images of atoms and molecules in a gaseous or liquid state because their atoms and molecules in these states are moving around so fast that they would be so hard to take a picture of.