DENSITY is a physical property of matter, as each element and compound has a unique density associated with it. Density defined in a qualitative manner as the measure of the relative "heaviness" of objects with a constant volume.
For example: A rock is obviously more dense than a crumpled piece of paper of the same size.
A styrofoam cup is less dense than a ceramic cup.
Density may also refer to how closely "packed" or "crowded" the material appears to be - again refer to the styrofoam vs. ceramic cup.
Density Comparison to Water: In chemistry, the density of many substances is compared to the density of water. Does an object float on water or sink in the water? If an object such as a piece of wood floats on water it is less dense than water vs. if a rock sinks, it is more dense than water.
Oil and vinegar salad dressing: The oil floats on the vinegar water mixture, while the solids sink to the bottom.
Oil spills: What happens when an oil tanker leaks on the ocean? The oil floats on the water since it is less dense, and this provides some opportunity to clean up the oil spills by skimming the oil from the surface of the water.
Ice: Everyone knows that ice floats on water, but did you know that this is an abnormal physical property of solid/liquid state of water? The more normal physical property is for the solid of a compound to sink in its own liquid.
