It’s not just about weight anymore…

Relate the arrangement of subatomic particles in a substance to its density and observable macroscopic behavior.

How close the atoms or molecules are to each other

More than “heaviness” - density includes how much space an object takes up!!

All substances have density including liquids, solids, and gases

Less dense

More dense

Least ‘compact’ of the phases of matter

Warm gases are less dense than cold gases – one reason for how weather works

Molecules are close together but can move past each other

Colder liquids are denser than warm liquids water at 50oC (120oF): 0.9880 g/mL water at 40oC (104oF): 0.9923 g/mL water at 30oC (86oF): 0.9956 g/mL water at 20oC (68oF): 0.9982 g/mL water at 10oC (50oF): 0.9997 g/mL

Cold water in lakes tend to sink (this creates a constant mixing of water, nutrients, and other substances)

The more dissolved solids in a solution, the more dense pure water (0% salt) = 1.00 g/mL 15% salt water = 1.11 g/mL 25% salt water = 1.19 g/mL

Color added to show layers

Coffee creamer is denser than coffee

The most ‘compact’ of the phases of matter.

Mercury density = 1.3600 g/cm3

Lead density = 1.1340 g/cm3

Mercury is a liquid metal at room temperature.

Lead is a solid at room temperature. Pool balls are made of lead. Would lead sink or float in mercury?

egg

Why do the bubbles rise out of the water?

Solid water (ice)

Liquid water

If you combine phases, you can get interesting densities:

Styrofoam (solid plastic with air

bubbles inside): 0.35 g/cm3

Whipped cream (liquid with air

bubbles): 0.50 g/cm3

Match the substance to its picture above:•NaCl: 2.16 g/cm3

•fluorine: 0.001696 g/cm3

•helium: 0.0001785 g/cm3

•magnesium: 1.74 g/cm3

•water: 1.00 g/cm3

Least to most dense:

helium: 0.0001785 g/cm3

fluorine: 0.001696 g/cm3

•It’s formula is F2!

magnesium: 1.74 g/cm3

NaCl: 2.16 g/cm3

water: 1.00 g/cm3

Using the mathematical definition of density, compare the densities of regular and irregular objects using their masses and volumes.A BIG Idea: Density is an intensive property. It is built into the

substance due to the compactness of the atoms.

Any size, any shape: aluminum is still 2.70 g/cm3

If an object’s density is 2.70 g/cm3, it MUST be aluminum

Density is the amount of mass in a space. So,

Density = mass / volume Jack has a shiny object. It has a mass of

6.35g and a volume of 2.35 cm3. What is the density of the object? What is it made of?

Jill has a gel pen. The gel pen has a mass of 8.30g and a volume of 2.00cm3. What is the density of the pen?

Density is the amount of mass in a space. So,

Density = mass / volume Jack has a shiny object. It has a mass of 6.35g and a volume of 2.35 cm3. What is the density of the object? What is it made of?

2.70 g/cm3, made of aluminum Jill has a gel pen. The gel pen has a mass of

8.30g and a volume of 2.00cm3. What is the density of the pen?

4.15 g/cm3

Try one of the videos on the plan to see how to determine densities in the lab…..

Then try some Ways to Practice and Extend Your Learning (also on the plan).