1. UNIT 5 MATTER

2. FREEZING Liquid water cools down zero degrees Celsius. It changes into ice. EVAPORATION Liquid water heats up. It changes into water vapour. BOLILING Liquid water heats up one hundred degrees celsius or more. MELTING Ice heats up. It changes into liquis water. CONDENSATION Water vapour cools down. It changes from a gas into a liquid. Water changes when it heats up or it cools down. These changes are reversible.

3. Oxygen molecule is an element because there is one kind of atoms. Water molecule is a compound because there is two kinds of atoms. MATTER Matter is made of atoms. Atoms are the building blocks of matter. Molecule: two or more atoms join together. Element: only one kind of atom Compound: atoms of different elements join together atom molecule element compund

4. Solid: the molecules are very close together. Liquid: the molecules aren’t so close together. Gas: the molecules can move freely. STATES OF MATTER

5. Melting : solid and heat liquid Evaporation: liquid and heat gas Solidification: liquid and cool solid Condensation: gas and cool liquid PHYSICAL CHANGES The substance changes but the matter stays the same.

6. CHEMICAL CHANGES Combustion: a substance is burned. New substance: ash and smoke. Oxidation: a substance reacts with the oxygen in the air without burning. New substance: rust. Putrefaction: organic matter decomposes. New substance: mould. The substances changes into a different substance.

7. Pure substance: can be elements or compounds. Mixtures: are made up of two or more pure substances. Mixtur es heterogeneous It’s possible to separate the substances easily. homogeneous We can’t see the individual substances, but we can’t still separate them.

8. The solids stay in the filter, and the liquid passes through it. Filtration The liquid evaporates and leaves only the solids. The solids crystallise and form crystals. Evaporation We can use a magnet to attract the solids. Magnetic separation Ways to separate the mixtures