Compound and Mixtures

Elements and Compounds
1. An element contains only one type of atom.
2. A compound contains different types of atoms joined together.
3. The formula of a substance tells us the number of each type of atom present in the substance.
4. The properties of a compound are different from those of the elements which it contains.
5. A compound is a pure substance which is made of the same particles.
6. A sample of a compound will always have the same elements present in the same fixed proportions.
Compounds and Mixtures
1. Compounds will react chemically to make new substances.
2. You can tell that a compound has reacted by observing what happens to it.
3. A mixture is formed when two or more substances are added together.
4. Air is a mixture of gases that can be separated into pure substances.
5. Air consists of nitrogen, oxygen, argon (and other noble gases), carbon dioxide and water vapour.
6. Each of the gases found in air has important uses.
7. Air can be liquefied and then individual gases can be separated by fractional distillation.
8. Sea water and mineral water are other examples of mixtures.
Elements and Mixtures
1. Elements and compounds melt and boil at a certain temperature.
2. Mixtures do not melt or boil at one particular temperature.
3. The melting point and boiling point of a mixture change as the composition of the mixture changes.

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