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1. What is an element? ( lesson15a)
2. What do you call a substance made form 2 or more different types of atom? (15a)
3. What are the particles made when 2 or more atoms are joined together? (15b)
4. What atoms are in a molecule of carbon dioxide? (15b)
5. How could you separate the mud from muddy water? (15b)
6. How could you get the salt from sea water? (15c)
7. The substances in crude oil can be separated because they have different ------- ------. (15c)
8. A mixture of different liquids can separated by ---------- ------------. (15c)
9. What is the formula of the molecule made from 2 hydrogen atoms and 1 oxygen atom? (15d)
10. Most of the chemical elements can be divided into 2 groups. What are these groups? (15e)
11. Name a  metal that reacts violently with water and is kept under oil. (15f)
12. Magnesium + oxygen --> ? (15f)
13. Which metal is one place below zinc in the reactivity series? (15g)
14. Magnesium + copper oxide --> ? (15g)
15. Which metal is more reactive - magnesium or copper? (15g)

ANSWERS

1. A substance that cannot be broken down into anything simpler. It contains only one type of atom.
2. Compounds.
3. Molecules.
4. 1 carbon atom and 2 oxygen atoms.
5. By filtration.
6. By distillation.
7. Boiling points.
8. Fraction distillation.
9. H₂O.
10. Metals and non-metals.
11. Potassium or sodium.
12. Magnesium oxide.
13. Iron.
14. Magnesium oxide + copper.
15. Magnesium.