4.3.1.1 - Density of materials

Define ‘density’.

Density - the mass of a substance to how much space it takes up (a substances mass per unit)

Give the equation for density.

Density = mass / volume

Give the unit for all the

density - KG/m3 or g/cm3

Mass - kg or g

Volume m3 or cm3

What is the particle model used to explain?

• the different states of matter

• differences in density

Describe the particles in a solid.

• A solid has strong forces of attraction that hold the particles close together in a fixed, regular arrangement

• Particles don’t have energy so they can only vibrate in their spots

• Density is generally the highest in this state as the particles are closest together

Describe the particles in a liquid.

• A liquid has weaker forces of attraction between the particles

• Particles can move past each other and form irregular arrangements

• Have more energy and move in random directions at low speeds

• Generally less dense than solids

Describe the particles in a gas.

• Almost no forces of attraction between the particles

• Particles have the most energy - they’re free to move and travel in random directions at high random speeds

• generally have low densities

Describe the pattern between density and states of matter.

Gases - generally lowest densities

Liquids - less dense than solids but more than gas

Solid - Density is generally the highest

Describe the particles in a dense material.

A dense material has it’s particles packed tightly together

The particles in a less dense material are more spread out.

What happens if you compress a less dense object?

If you compress the material it’s particles would move closer together - becoming more dense