Density and Kinetic Theory

• The density of a material is defined by the mass per unit volume.
• Density = mass / volume
• Density equation

  A) Mass

  B) Volume

  C) Density

  
• The gradient of a mass-volume graph represents the density of a particular material.
• Molecules in a solid are packed close together and vibrate about fixed positions. Solids have fixed shapes and volumes. High density is caused by tightly packed molecules and strong forces of attraction between molecules.
• Molecules in a liquid are farther apart than in a solid. They are not in a fixed position. Liquids have a fixed volume but take on the shape of their container and have a medium density, as the forces of attraction between the molecules are not as strong as those in a solid.
• Molecules in gases have large distances between them and move in all directions. Gases completely fill their containers. They have a low density as their particles are far apart and the forces between them are weak.
• Kinetic theory explains the properties of solids, liquids, and gases according to the arrangement and motion of their molecules