Knowing how far apart molecules are in each state best ranks solids, liquids, and gases from least dense to most dense.
<em>Density</em> describes how much mass is contained in a certain volume
That is the definition of density: <em>Density = mass/volume</em>.
If you keep the volume constant but make the molecules closer together, you will be able to pack in more molecules (more mass).
In <em>solids</em>, the molecules are close together. They have the most mass in a given volume, so they have the greatest density.
In <em>gases</em>, the molecules are far apart. They have the least mass in a given volume, so they have the smallest density.
In <em>liquids</em>, the molecules are a little further apart than in solids. Thus, their density is between that of liquids and gases.
<em>close together _________________________________far apart </em>
<em>solids___liquids ________________________________gases
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