Why might scientists who study changes of state build models showing the arrangement of particles in a substance?

Building models showing the particle arrangement of the substance would help clearly understand the characteristics and behaviors of certain substance at a specific state. Also, this would help ascertain the state/nature of a substance. For example, particles in a solid state are arranged in a tightly packed manner normally with a distinct regular pattern while substances in a liquid and gaseous states doesn't have any particular arrangement at all.

List the following gasses

Engineers have contribute to society in many ways like making the technology we use today or any type of power energy material