Y7- Science

A material is any substance with a name. Mixtures are made up of more than one substance that can be easily seperated. The property of a material is something about it that we cam measure, see or feel. A pure substance is made up of only one type of material.

The properties of a substance depends on 3 factors: What the particles are like, How the particles are arranged and How the particles can move around.

Properties of a solid: Solids stay in 1 place and can be held. Solids keep their shape and they can be shaped into different shapes.

Liquid: Can flow and poured. Change shape in whichever container they are in.

Gas: Gases are often invisible, gases don't have a fixed shap. Gases are compressible.

Melting: The objects particles begin to move faster and faster until the structured particles freed. Now it's a liquid.

Freezing: The objects particles have less energy and get closer together, this forms a solid.

Boiling: The particles gain more energy, spread out and form bubbles. Using the energy, they try to get freed and they free themselves and rise up and out of the container then they attach with the air particles in the air and make gas.

Evaporation: Energy causes the molecules to move faster. If they gain enough, they will break away. This turns into a gas without boiling.

Condensation: As the molecules of a gas lose heat, they lose energy too.  They slow down. They move to gas molecules and connect then form a liquid.

Diffusion is where, e.g, the coffee particles move from the coffee machine (are of high concentration) to the rest of the coffee shop ( an are of low concentration). Then they mix with gas particles which then goes through your nose and thats how diffusion happens.

Diffusion is a random process. 3 factors of diffsion: Temp. Particles size and state of substance. 

On a hot day, the air particles gain more energy and move faster. They collide faster with the rubber and the pressure meaning the balloon will burst.

In the snow, the balloon will collapse as when the temperature is decreased, the air particles move more slowly, less collisions and the pressure decreases. 

The force per unit area is the gas pressure. Gas pressure is caused when gas particles hit the walls of their container.