STATES OF MATTER

DENSITY

Learning PointsLearning Points• Explain the different masses of

materials with the same volume in terms of particle spacing and relate this to density.

DensityTake a look at the two boxes below. Each box has the same volume.

If each ball has the same volume, which box would weigh more? Why?

The box that has more balls has more mass per unit of volume. This property of matter is called DENSITY.

Density

Density = mass (g)volume (cm3)

It can be worked out using the following equation.

Density is a measure of how many particles of a substance are in a given area/volume.

Solids are usually the most dense, followed by liquids and then gases.

Density of SolidsSolids have their particles closely packed together.

In liquids the particles are further apart.

With gases the particles are widely spaced

apart from each other.

Density of Solids

The steel ball is denser than the apple because it has MORE particles in the same volume.

Different solids have different densities.

QUESTIONWhy is this person not sinking under the sea???

ANSWERShe is less dense then the seawater and so does not sink.

Float or sink

gettyimages.com

Less dense substances float on more dense substances.

Density = mass (g)volume (cm3)

More dense substances sink.

Remember

http://www.school-for-champions.com/SCIENCE/fluidfloating.htm

Float or sink

http://www.seed.slb.com/en/scictr/watch/bathroom/duck.htm