Science - Matter (Year 9)
List some separation techniques
* Filtration * Distillation * Sieving * Absorption (more on learning guide.)
What is diffusion?
**Diffusion is the movement of particles from an area of high concentration to an area of low concentration.** The rate of diffusion depends on the size of the particles and the amount of energy they have. Bigger particles move more slowly than smaller particles. The hotter the substance the more energy the particles have, the faster they diffuse.
What is expansion?
**When particles in an object are heated, they gain energy and move faster. This causes the particles to push against each other and become slightly further apart, we call this process expansion.** Expansion can cause many problems. expansion joints are placed in railway lines and bridges to allow for expansion on hot days and contraction on colder days. During heat waves railway lines sometimes buckle if the space left in not big enough.
What are the parts of an atom?
Electrons: are found of shells surrounding the nucleus. Electrons have a negative charge. Protons: are found in nucleus. Protons have a positive charge. Neutrons: are found in nucleus. Neutrons have no charge, the are neutral.
What are the differences between compounds, elements and mixtures?
Element - An element is made up of one type of atom. Compound - A compound is when 2 or more different types of atoms are chemically joined. Mixture - Mixtures consist of two or more different substances, not chemically joined. There can be different amounts of each substance.
What is matter?
Everything is made up of matter. Matter is made up of very small particles called atoms.
What is a chemical change?
In a Chemical change a new substance is formed and can not be easily reversed. We can identify a Chemical change has occurred when we observe: -a gas is given off -heat energy is produced -Light energy is produced e.g: cake mix becomes cake.
What is a physical change?
No new substance is formed, this often involves a change of state. Physical changes can often be easily reversed. e.g: ice - water - steam
What do the particles do in each state?
Particles in a solid are: - packed tightly together in an orderly arrangement - only vibrate a little Particles in a liquid are: - packed slightly apart from each other and held weakly together -can move slowly past each other Particles in a gas are: - the particles are far apart -free from each other - moving in all directions quite quickly
What are the properties of solids, liquids and gases?
Solids · holds their shape · fixed volume-can not be compressed Liquids · take the shape of the container · fixed volume - can not be compressed Gases · take the shape of the container · volume of container
What are the states of matter?
Solids: Ice, Aluminium, Dust Liquids: Water, Oil, Milk Gases: Steam, Oxygen, Carbon Dioxide
What are the changes of state?
When a solid is heated and gains energy it turns into a liquid this is called melting. When a liquid is cooled the energy is removed and it turns to a solid, this is called freezing. When a liquid is heated the particles gain energy and it turns into a gas this is called evaporation/boiling. When the gas is cooled , energy is removed and a liquid is formed this is called condensing. When a solid is heated and it turns straight into a gas without turning into a liquid first this is called sublimation. When a gas turns directly into solid this is called reverse sublimation.
What is contraction?
When we remove the energy the particles move more slowly and move closer together, we call this contraction.