Density Curriculum

Section 3—Lesson 11: What Does It Mean for Density to Have Multiple Contributing Causes?

Understanding Goals

Subject Matter

• One cause of differences in density is the different masses of different atoms.
• A second cause of differences in density is the strength and structure of atomic and molecular bonds. This is most important when thinking about solids and liquids.
• A third cause of differences in density is mixed density, for instance, when gas molecules are interspersed with other molecules, or when something is hollow inside or has "air pockets," making it a combination of air and the material around the outside.

Causality

• Density has multiple contributing causes. Not every cause is involved in every situation where density is in play.
• You can't compare objects by using just one of the causes of density alone. It will leave out other important relationships that could contribute to the resulting density. You also can't assume that every cause contributes to every situation.